BCM Community

[NOTE:  This is a parallel post to something I put on another bus site.  If that's not kosher, please let me know.  I'm really just trying to get this problem solved, not trying to be a pain.  Thanks!]

Howdy everyone. I'm quite sure you've answered this question many times, but my searches through the archives aren't getting my the answers I'm looking for. If you know of an exhaustive post already done, please point me to it. If you have ideas, please let me know.

I am desperately seeking a solution to the repowering of my existing 8V71 and Fuller 5spd manual to something else. ANything else. I hate that engine. It's loud and sucks fuel and pukes oil. It has no turbo, the tranny has no overdrive. It's killing me one mile at a time and I want to upgrade. It's burned four valves in two years, uses a gallon of oil every 400 miles, and just badly needs an overhaul (which the previous owner said it already had). I'd rather spend the money on some improvements.

SO... what's the optimal engine/tranny combo for repowering an MCI-9 with 8V71? I'm a guy that just wants to get me and my family from point A to point B reliably and as efficiently as possible. I don't need extra horsepower, I don't need fancy anything - well... cruise and jakes would be nice if easily incorporated. I'd like the engine to have turbo and the tranny to be either autoshift or automatic, though this is not essential as me and my kids have learned on this Eaton Fuller 5spd and are comfortable with manual.

Also, where are salvage sources for these powerplants?  Wrecked trucks, fleet sales, etc.?  Any help is greatly appreciated.
Many many many thanks in advance for your expert and thoughtful help getting me back in service.

Boy you sure picked a highly debated topic..The 8 v 71 is a dependable work horse..if your happy with the level of performance repair it..if you go to a 8v92 you will need to change radiators and loose fuel mileage will be up to 20% less.  Automatic swap is nice addition,but will also cost fuel..6v92 is a poplar swap with a automatic but hp increase is minor.  Others will comment for sure. As far as I'm concerned it's your decision..How much of the work can you do yourself? in frame? prob not a complete rebuild  before -lots of sellers say recently rebuilt..and they might of only rolled bearings in it or less. In my Mci 8 with a 8v71 automatic I got 6.8 mpg..should do a little better with the standard.

where it says search up to the right  put in Engine swap..several links to what others have done  one was a 8v71 to 6v92 swap

Or my way ...

http://home.earthlink.net/~diehls0792_1/BusSection10.html (http://home.earthlink.net/~diehls0792_1/BusSection10.html)

Let me know if you want more pictures or information as I'd be happy to chat about it.

I was at Quartzsite last week and a guy had a trailer load of different Cummins engines for the 300 hp L10 he was asking 500 a pop,the L10E with the ECM were 800, M11 were 1000,1250 for the electronic version and ISM with the ECM for 2 grand not bad prices but no way of knowing what you would be buying.
Melbo has a L10 and ZF auto in his MCI and he likes it


good luck

Goodness Brian,  I don't think I can wait that long or spend that much time on a swap.  It needs to be finished by mid January next year.  I like the ISM, and the mileage you're getting, but I don't like the idea of cutting the floor.

Arl, cross posting is OK, but then you don't get as good of a dialogue as people respond to the thread.

Brian's conversion is an excellent example of what can be done.  My project pages (in signature) has some details on my conversion in an Eagle.  The process has many similar construction processes between various coaches.

As has been said, the subject is extremely broad and complex.  I wrote a three part series on engine conversion in Bus Conversion magazine.  It was not a how to do, but rather, all of the things you need to consider and all the options that exist.

Not sure how you searched, but the topic has been covered in many threads over the years.

Part of your study must address who will do the conversion.  If you think about doing it yourself, you will need a ton of skills and equipment.  If you have someone else do it, plan on at least $10K in labor for a cheap shop and up to $30-40K for an experienced shop.  Many shops will tell you they can do the job since the stuffed a Chevy in a Jeep, but that is not even close experience.

If you think about going to a four stroke, then gearing will be a big issue.  Buying the engine is a gamble (I lost) and can create a great deal of heartache and mental anguish (and added $$$$).

Some folks have added a turbo to the 8V71 and are happy with the modification.  Sounds like you can balance a conversion against a rebuild cost.  However, the rebuild will always be less expensive.

Just some random thoughts.

Jim

I have had an excellent time with the L10 cummins -- I may not be as enthusiastic about the ZF -- not because it isn't a good transmission but because it is not well supported in the US -- the more places you can get service the better off you are and the L10 can be serviced anywhere as can many transmissions.

Also the engine runs up to speed and cool on temps -- Mike had his fuel pump rebuilt and got a bump up in HP

I have about 20K miles on my repower

L10s are easy to find -- to use a jake will take a little mod for the height of the engine

I would be glad to provide more information if you want

HTH

YMMV

Melbo

arl, you answered your own question.  There is no way to do an engine conversion in the time frame you have.  Brian's conversion is typical of the very involved process.

Given that you will not be able to do a conversion, you need to see if you can get your engine performance improved.  First, with all the oil, I have to wonder what oil you are using.  You must use straight 40WT oil specified by DD.  Next, you need to find someone who can run the rack for you.  

Then learn to live with it for a while until you can gather all the information you need to make a very complex decision.

Jim

Just as a random thought, these buses have run countless miles with various engine/tranny combinations, none of them are racecars but all were at some point well thought out for the most part and good running combinations, if one isn't measureing up to a persons expectations I'd check the possible combinations of fixes available before replacing the engine and possibly opening a major can of worms, sometimes just the proper oil will make a world of difference, straight 40wt cf2, tho many will say 15/40 is fine, it isn't, another heart breaker can be an out of adjustment on the rack, make the best of engines run like a ruptured duck in a bean pool, lots of possible fixes that'll give new life to what appears to be a hopeless case sometimes.

you  said  a gallon every 400 mile..The question I have is it burning it? is it leaking it?  Do you have smoke?  what color?   You ask for source for engine -just post here//.need one on one help? tell us what part of country your in.   Bob in SW Indiana.

In your position, there is only one thing I would do.  I would find and buy a complete power package from another MC-9.  That would be transmission, engine, radiators and all.  I would probably look for the more common 6V92/Allison 740.  I would buy the best set I could find, slot it in there, and pray that not rebuilding turns out to be a good idea...

I would not look for an overdrive transmission unless I was changing to a four stroke engine.  The two strokes have to run at their designed rpm range in order to work properly.  That's just the way they are...

Brian

   You might check some post that Tom C has explained on his re-powered 8V-71 to the TURBO version.  Some real good articles.

    Steve 5B........

You talk of horrible fuel mileage. What is your fuel mileage? Your driving style will have a huge impact on that. If you run 55mph, you will get better than if trying to run 70mph.

Having your current engine properly inspected by a good 2 stroke mechanic & tuned (if inspection indicates it needs it) will be a wise investment.
The wrong oil will cause excessive oil consumption - especially in an older motor.

Another thing, you can ruin a perfectly good 2 strokes by driving it like a 4 stroke. You must get the rpm's up. If you're pulling a hill & you can't accelerate, you're in danger of hurting the motor - watch the water temp, the 2 stroke won't survive above 200F.

To Everyone, a hearty thank you for your time and attention.  You could be doing other things and I appreciate your willingness to share your wisdom with me.

I hear the points about balancing the cost of repower (time, aggravation, expense) with the cost of rebuild.  I can probably get a rebuild done for under $3K as my diesel expert also mentors my boys and they do most of the work under his supervision.  If you ever need work done in/around southern KY, call Ronald or Kerry Matney at Matney Diesel 270-932-7889.  They're amazing people.

I just don't like the 2-strokes in general.  I know that probably hurts some feelings, but I don't.  Loud, smelly, messy.  I don't like my tranny either.  Manual 5spd, raking all the time, clutch is annoying and generally useless.  The whole thing is annoying.  But that's not reason enough to spend countless hours and God-only-knows-how-much money making it different.  Unless the repower can be done reasonably and timely - and make a huge difference in the end.  That post from Brian Diehl on his repower to an ISM was enlightening - but he's apparently much happier now.  I like the idea of better mpg.  9 mpg or better will pay back over time as I currently get 6.2 on average.  We drive about 20-30K miles per year.

My coach is set up wonderfully so I'm reticent to just get a different unit.  But that's an option too I guess.

Bottom line is I need to get to the place where my bus is working for me, not the other way around - however that works.

I'm in Southern Central KY, near Greensburg, if that matters.

Thanks so much everyone!  Keep the wisdom coming and I'll put it to use - I promise!  In fact, I'm going to write up a more exhaustive description of our situation and see if that doesn't help drill down to a clearer answer.  I'll post it soon.

Alan

Just as a heads up -- I only get about 7 mpg --- drive it fast and 6.8 --- drive it slower and 7.2

I did not figure I could pay back the repower from the fuel mileage but because I didn't have to rebuild the two stroke and change the tranny to auto

I would have spent the same money to upgrade and keep the two stroke.

YMMV

HTH

Melbo

I spent a lot of time researching a swap to a Series 50.  I spoke to a number of people who had done this.  It needs a new differential gear or a high overdrive gearbox, or both, and the average timeframe for the physical install was around 45 days of actual work, whether bought out or done by a highly skilled owner.  The cost was estimated $15K to $30K, not including a transmission.  For me the biggest issue was going to be getting the computers talking to each other and to the bus...

I decided 3 mpg wasn't worth it.  People who had done it uniformly praised the change.  I guess I decided that if I wanted a bus with a 4 stroke, I would just buy one and be done with it.

Brian

Alan, on this and BNO, you have been given some pretty good advice.

If you are SURE that your engine is toast, I would do a rebuild since you have the ability to get it done inexpensively.  The engine is easy to remove and your boys can work on it a lot easier when it is out.  Again, make sure that your engine is, indeed, toast and is not just leaking or using oil because someone stuck the wrong oil in it.  As you probably know, you can inspect the cylinders without tearing down the engine.

Then, stuff it back and and drive it while you do your homework on a four-stroke. You can recoup a significant part of your rebuild cost when you replace the engine by selling your 8V71.  Keep good records and take lots of photos so that you can document the rebuild.

After you do your homework - take your time - you will make a good decision.  20-30K per year begins to add up in terms of fuel savings.  I estimated in my article that I saved about $4K in 50K miles of driving. 

Since you have a clutch already, then a truck transmission with overdrive makes good sense when you go to the four-stroke.  Better yet, the AutoShift is also a good way to go.  I really don't think an OD will do you much good with the 8V71, as you need to keep it wrapped up.

Jim

Jim, it is not funny but I had to laugh your 4000 dollar fuel saving went by/by with all the problems you have had lately your in the hole buddy.
If the guy doesn't like 2 strokes best for him to get something else he will never be happy that is the reason most of the 2 stroke people don't waste their time responding.


good luck

Clifford, good talking to you today.  Yep, by having to get the second Series 60, my savings were overshadowed by the costs involved.  Maybe I could look at it as paying for most of my replacement engine  ;D >:(.

My gut feeling is that the 6V92 would have been a problem if I had put a ton of money in the rebuild and then tried to have it pull 46K pounds up these CO hills (service truck is 9.6K).

I talk a little about buying an engine in my article.  I made a huge mistake believing that Series 60 engines were all  "million mile" engines.  I worked with statistics much of my working life and should have understood.   My engine had over 650K miles and I had a very uneasy feeling.  At the time, it was about the only engine available within a reasonable distance.

Southern Oregon Diesel got bitten several times by installing used engines in buses.  As I understand it, they would only install engines they rebuilt after they got bitten several times.

The issue today is that everyone wants to avoid four-stroke EGR engines.  That dictates engine prior to about 2003.  It follows that these engines have a ton of miles on them.  Not a good situation.  I have suggested to a couple of folks that the consider getting a salvage engine and have it rebuilt.  Hard to justify the cost when you only put a limited number of miles on in a year. 

For my second engine I was fortunate to find an engine in a wrecked truck where I could verify that the engine had be rebuilt (220K miles previously) by a DD dealer (got receipts from both the owner and the DD shop).  Even that does not guarantee that I will not have problems. 

Because I did all the work myself, I am not out much more than it would have cost to rebuild my 6V92 that spit up (at DD rebuild cost).  Having said that, if I paid myself $5 per hour, the conversion would have cost me about a million dollars  ;D ;D ;D

Jim

Rebuilding you're 8V-71 will be the best and cheapest way to go.  Once overhauled properly, you'll probably never have to do another over haul again-suggest you restrict your injectors to N60's for best fuel mileage and longevity.

Another way to go is to find a crashed trash truck with a Cummins ISM and Allison world transmission. Buy the whole truck (make sure it hasn't been pilfered) so to get all the wiring and parts for the electronic engine and transmission.  Then you'll have an engine that will get 8-10mpg and and enjoyable automatic transmission to drive (I drove 1.3 million miles truck with 13spd transmission-I have Allisons now).  Good Luck, TomC

IMHO, a commonly underestimated engine is the little Cummins ISB, specifically the latest 6.7L. Without the emmissions crap, they'll happily make around 400 hp and 800 lb-ft of torque.

Now, they'd never stand up to commerical duty cycle at those power levels, but for an RV, it's perfect. The best part is, they're everywhere in junk yards from late Dodge HD pickups.

The only think I'd be worried about is the 68RE transmission. They're fine for the Ram's 26,000 GVW, but on a coach with 36,000 GVW, I'd spend a grand or 2 beefing it up and add a big cooler. That said, hot shot haulers routinely gross 36,000 stock.

You'd have to gear the diff to run about 2000rpm @ 60mph. Which requires roughly 5.13 on a 42" tire. By doing so you'd have a passing gear (5th) of 2600rpm@60, and hill climb (4th) of 3000rpm@60, with a whole bunch of gears for lower speed - a lot better than the stock 8V71, especially at altitude.

You'd easily get 10mpg with this setup, and have minimal cooling requirements.

Roy,
   I don't doubt your word, and if you're right, I'd be very interested to pursue your suggestion.  But I have a few questions:

1.  Is the ISB a 2-stroke?  Why the high rpms?  3000?  That sounds high, even for me, who is used to 2300 rpm cruising speed at 64mph.  I thought THAT was high.  The poor 8v71 sounds like its hurting itself.

2.  10mpg is my dream goal.  Are you just shooting from the hip or is that really possible?

what do the rest of the board readers say about this?

thanks!
Alan

The ISB is the dodge ram pickup truck engine.  it's a good engine but it makes its power from rpm's not raw displacement.  I wouldn't put one in an MC-9 on a bet.  It's OK up to maybe 25,000 lbs and slow, you'll be 10K over that and you already think the 8V-71 is slow.  All that said, you can over-fuel the thing to death and get 400 or even 600 hp from it, for a little while!  Mind you, I think it's the best pickup truck engine every created, and the earlier versions were even better, for pickup truck use...

ISB 5.9 L
ISL 8.3 L
ISM 11 L 

The ISB is not going to cut it in a 40 ft bus


good luck

reason I ask where you were is their is a preowned engine guy in Central City-Ky he also does rebuilds       Bob

OK. I hear the cautions about the ISB (5.7 L) not being big enough.

So what about the ISL?  I have a friend who has one with an Allison world transmission in a wrecked country coach RV for $7k, not including controller/remote.  I could probably get it for $5K plus the controller (which will then require programming as well) for another $2K.

Is that reasonable and doable?

8 v 71 = aprox 9 ltr   61 cubic inches per ltr  568 inch in 8v71

I would personally stay far away from an ISB.  They put out a lot of HP, but not a lot of torque.  Stock they put out less torque than an 8V71 I believe.  A Series 60 puts out around 1,350 lbs of torque and up.  Torque is as important as HP in a large vehicle.  Remember that 26,000lbs is the maximum load for a pickup pulling a trailer.  It is very rare for most pickups to be loaded that heavily.

Diesel pushers used to use a lot of the ISB, but now they mostly use the ISC or similiar and bigger.  Freightliner uses the ISB in their diesel puller today, but that is about it.

I knew I'd open up a can of worms with the ISB. Think about this: thousands of 40' school buses, grossing 30,000+, run around everyday with ISBs tuned to mid 200hp (for commercial longetivity).

Now, put on 5000 lbs more, but add 150hp, and suddenly it's not possible? A lot of people doubt it simply because it hasn't been done, not because it isn't possible. The MCI 102 I drive at work dynos 290 rwhp with an 8V92, nobody ever doubts its ability. Now, put in a 350 rwhp ISB, and all of sudden it's big no-no?

Yes, there is one catch - you'll have to run high rpm due to lack of torque. But compared to what? An ISM? Sure. But 8V71N? which makes what, 900 lb-ft with common injectors?

Remember, toque can always be made up from gearing, but hp always remains constant (law of physics). As long as you're making the horsepower needed at the crank, gearing will ensure enough toque is available at the rear axle. This is why I stressed the importance of a 5.00+ gearing.

Quote from: robertglines1 on October 27, 2010, 05:56:21 PM
8 v 71 = aprox 9 ltr   61 cubic inches per ltr  568 inch in 8v71

You forgot one important factor: manifold pressure.

8V71 is 9L @ 0psi, or converting to 4 stroke: 16ish Liter (due to volumetric efficiency factors).

6.7L ISB @ 30 psi = 20ish Liter @ 0psi. Then factor in 3000 rpm vs 2000 rpm, and all of a suddent the little ISB is pumping double the air of an 8V71.

Quote from: belfert on October 27, 2010, 06:13:53 PM
Remember that 26,000lbs is the maximum load for a pickup pulling a trailer.  It is very rare for most pickups to be loaded that heavily.

Pound for pound, it takes more hp to move a truck+trailer comobo than a bus, due to much better aero of the bus. A pickpu with 40' toy hauler has a huge frontal area, tons of gaps midway, which causes a lot of turbulance losses.

Yes, it's it rare to see 26,000 lbs pickups outside of hotshoting and RVing, that's why I stressed an ISB would not work for a commercial bus running round the clock.

Keep in mind though, some pickups, like F450 and F550 have GCWR of 33,000 lbs, with an engine (Powerstroke) of even lower duty cycle than an ISB.

Quote from: bevans6 on October 27, 2010, 05:18:51 PMAll that said, you can over-fuel the thing to death and get 400 or even 600 hp from it, for a little while! 

That may be true for an early 12V, but with modern iterations making 350hp stock, you're a DPF and EGR delete, intake, and VERY mild tune away from 400hp. The point I was trying to make, is that an ISB would have just as easy a time making hp, compared to the 8V71, whether 300, 350, or 400 hp.

600hp is an entirely different story. Duty cycle at those levels would be too short even for recreational use.

Warning I am in no way a engine person

My thoughts are simple  take a dt466 up the hp and torque
It should last maybe 200.000 miles
Rebuild kits less then $1000 and parts available at more stores.
There is way less weight, length, height etc....

Again no expert but just thinking opps.

Lonnie

Quote from: arl on October 27, 2010, 04:56:33 PM
Roy,
   I don't doubt your word, and if you're right, I'd be very interested to pursue your suggestion.  But I have a few questions:

1.  Is the ISB a 2-stroke?  Why the high rpms?  3000?  That sounds high, even for me, who is used to 2300 rpm cruising speed at 64mph.  I thought THAT was high.  The poor 8v71 sounds like its hurting itself.

2.  10mpg is my dream goal.  Are you just shooting from the hip or is that really possible?

what do the rest of the board readers say about this?

thanks!
Alan

Alan, as an engineer, I like to backup my arguments with numbers and calculations, instead of simply stating something can or can't be done.

First of all, 3000 rpm is the max for an ISB, not cruising. I put cruising at 2000 due to the following:

8V71 w/ N65 injectors makes 800 lb-ft @ roughly 1700rpm, which is typical cruising speed @ 60 mph. 800 * 1700 / 5252 = 259 hp.

6.7 ISB makes 700 lb-ft @ 2000 rpm with mods mentioned. 700 * 2000 / 5252 = 266 hp.

Since the ISB is making just as much hp @ 2000rpm, as an 8V71 does @ 1700rpm, we can conclude the ISB has just as much reserve power left, at cruising, as your current Detroit.

However, if a hill comes up, the ISB can instantly downshift TWO gears, putting it at 3000 rpm, and 400hp, where as the 8V71 is stuck (you can't downshift if already @ 1700 rpm). 400 hp, regardless of torque, will yield MUCH better climbing power than 259 hp.

Lack of torque only applies when you CAN'T downshift to take advantage of gear multiplication.

10 mpg is possible, at 60 mph, based on two observations:

- I routinely get 11 mpg, at 60 mph, in a 30,000 lbs loaded school bus. Coach is slighly heavier, but has better gearing. At hwy speeds, wind drag is the pre-dominant factor.

- pickups hauling 20,000 toy haulers get 10 mpg, when they cruise at 60 mph. Slighly lighter combo, but again, MUCH worse aerodynamics.

change rear diff  min $3500 if you can find a 5 plus gear ratio to fit your housing.then extreme cost. Our family pulls diesel  4 wheel drive trucks and yes we make extreme horespower & torque. when they let go they are scrap metal..so the math adds up to making torque and horse power. Fact is cubic inches equals dependable Torque & horsepower. don't have to be on the edge to do it just plodding along..You can do anything! put money in top speed /performance comes out bottom..Fyi mci put turbine in bus in 1979. When Steve got it in the 90's it had already been changed over to a 8V71.

Quote from: robertglines1 on October 27, 2010, 07:58:15 PM
change rear diff  min $3500 if you can find a 5 plus gear ratio to fit your housing.then extreme cost. Our family pulls diesel  4 wheel drive trucks and yes we make extreme horespower & torque. when they let go they are scrap metal..so the math adds up to making torque and horse power. Fact is cubic inches equals dependable Torque & horsepower. don't have to be on the edge to do it just plodding along..You can do anything! put money in top speed /performance comes out bottom..Fyi mci put turbine in bus in 1979. When Steve got it in the 90's it had already been changed over to a 8V71.

I don't disagree with that, but "modding" is not black and white, it's grayscale.

Straight pipe, larger intake, slightly advanced timing and additional fuel; is totally different than: built injection pump, huge injectors, compound turbo...

The former gets you a reliable 400hp ISB, the latter gets you an 800hp weekend toy. OEM engineers have a crapload of restrictions that we don't have. These "OEM restrictions" is the only area I feel safe playing in.

When determining torque you must remember that torque (work) is most properly defined as Mass * stroke - FWIW

Quote from: niles500 on October 27, 2010, 09:32:48 PM
When determining torque you must remember that torque (work) is most properly defined as Mass * stroke - FWIW

Hmm, you lost me on this one. What do you mean by "determining" torque?

Torque is a force measurement, not work; it's force in angular reference. I have no idea where the mass and stroke comes from.

This is a pretty good thread. I would really make sure you read the articles that Jim wrote in the magazine. If you take your time and dont jump into the repower and do LOTS of real research you will be $ ahead and alot happier in the long run. Sure the smart thing to do is get another coach with the power you require. But go to a rally and listen and learn from people who have the knowledge and actual experience. We have some antique units and wanted more power,hill climbing,economy etc and were drooling ver the 6V-92's in some of the 04's at Arcadia. We ended up with a 6V-71 and allison and 3.73 gears and its perfect for OUR rig and application. LOTS of people told us we would be sorry and not have enough power or HP etc with the 6V-71. The first thing, it was rebuilt by someone who knew what they were doing. Pay attention to the good advice do lots of research and dont jump into this. I would really check out all the engines down in Arcadia at New Years Rally even if you just fly in. The knowledge is INCREDIBLE. The best part is all the rigs that have things that cant be done in them.

As you are a student of the ISB why don't you post a graph of the hp curve and torque curve of the ISB set at 400 hp for these guys compaired to the 8v71TA 350 hp set at 2500 rpm


good luck

The manufacturer has to be concerned with more than just duty cycle.
There is the predictability of failure rate that is of great concern. It only takes a few failures to overshadow a good product.

How happy do you think arl will be if his 'freshly tuned to 400 hp' takes a dump after just 40,000 miles?
I know there are no guarantees, but the light duty ISB is definitely more prone to failure than a heavier built engine.

I'm not saying don't do it, but I am saying it ain't as simple as comparing apples & oranges.

Maybe arl would be happy with an ISB simply because he would be able to drive it like a car. . . .

BTW, a 8V71 at 2000 rpm sounds like a 6cyl 4 stroke at 5,333 rpm, No wonder it sounds like it is screaming!  8)

Clifford is absolutely right. You can't compare motors without looking at the power curves.

Something to keep in mind is that the raw cost of the engine is only a portion of the cost of the swap.  For my money, if I was going to do a swap I'd want to know that the new engine was going to be a significant improvement over what it replaced.  In our case when the chips were down I went with a rebuild.  I think it cost me about 2/3 of what it would have cost to swap engines.  Maybe in my own shop on my own time I could have done the swap for what it cost me to have Luke do a good rebuild but that would have involved a used engine and a lot of time.  When I was all done I'd have still had a used engine with a somewhat uncertain history.  As Jim's experience should clearly demonstrate that route is not necessarily foolproof.

Quote from: kyle4501 on October 28, 2010, 08:20:14 AM
How happy do you think arl will be if his 'freshly tuned to 400 hp' takes a dump after just 40,000 miles?
I know there are no guarantees, but the light duty ISB is definitely more prone to failure than a heavier built engine.

Care to explain why the ISB would take a dump at 40k miles?

I'll list my choice of mods again: DPF & cat delete + larger pipe, EGR + cooler delete, cold air intake (easy on bus), slight timing advance (raise power and NoX levels).

If the ISB, by design, is more prone to failure, then we must have a lot of students late for class every morning... I drive an old Thomas with 1/2 million kilometers, grossing 30,000 lbs for the last 15 years, and still runs like a champ, all on a little 5.9. That's more miles than almost ANY busnut needs.

I am assuming if you are making that many mods to a 6.7 ISB that you must also be messing with the computer.

School buses have always had fairly small motors as ones operating in urban areas rarely get up to highway speed.  I'll bet that ISB in a bus is rated closer to 250 HP than to 400 HP.  Lower rating means longer life.

Quote from: luvrbus on October 28, 2010, 06:46:56 AM
As you are a student of the ISB why don't you post a graph of the hp curve and torque curve of the ISB set at 400 hp for these guys compaired to the 8v71TA 350 hp set at 2500 rpm


good luck

I'm not a "student" of the ISB; I believe in innovation. If we keep thinking: this has worked for years, ain't broke, don't fix it. Then well, we'd still be driving steam locomotives.

Here's a dyno of a truck around 400hp, keep in mind this is at the WHEELS. For the sake of discussion, let's assume it's at the crank:

(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.pittspeed.com%2Fuploaded%2FDually.bmp&hash=8f34377d3ab1223a84d3eb3bd6dc943f87ca7fcc)

Look at the red curve. Keep in mind real torque does NOT drop off like that; it's the failure of a dyno to measure proper torque once transmission converter unlocks. Manual tranny dynos are flat till about 1400 rpm.

Before anyone says "torque is what matters", let's calculate the torque at the rear axle, since that's what really matters in the end. 68RE ratios are as follow:

1st 3.231
2nd 1.837
3rd 1.410
4th 1.0
5th 0.816
6th 0.625

Assume 5.88 rear end ratio, 40" tire, then at 60 mph:

6th: 1867rpm, 620 lb-ft at engine, 620 * 0.625 * 5.88 = 2278 lb-ft at axle  [Eco cruise]
5th: 2430rpm, 700 lb-ft, 700 * 0.816 * 5.88 = 3358 lb-ft  [Passing / small hill]
4th: 2964rpm, 650 lb-ft, 650 * 1 * 5.88 = 3822 lb-ft  [Hill climb]

We can do this for any speed, any gear. For example, steep hill @ 30 mph:

2nd: 2712rpm, 690 lb-ft, 690 * 1.837 * 5.88 = 7453 lb-ft

Can even back calculate this for 34,000 lb coach to find gradability:

7453 / (20" / 12) = 4472 lbs of thrust
4472 / 34000 = 13%

I don't know about you, but climbing a 13% steep hill at 30 mph, in a 34,000 lbs coach, seems like very decent performance to me. Something I wish my bus can do right now...



Now, let's compare that to some examples of 8V71N, TA, or 6V92. My guess is that the little ISB can hold its own!

Roy,

I feel the need to defend some of our proven experienced folks here. A friend told me once "Sometimes it's not what you say as much as how you say it" and you sure don't seem like you want or need our most experienced guys input so why don't you show us and quit telling us about your 400 HP no problem to install or modify, long life ISB. I'm betting $15-20k installed before you tighten the last bolt. Of course you could ask guys like Clifford or Brian Diehl or Jim who have actually done a repower too.

I think we'll all be singing your praises in about 250k miles of passing the best minds, two strokes and technology we have to offer like we're standing still.

Most of us that have been here awhile tend to find ourselves asking folks like Clifford and Tom C instead of telling them. I'm all for hearfelt discussion but these guys are our friends that help us with our ancient and out dated technology year in and year out.

No harm no foul just show some respect to our collective intelligence as well as your own.

Just my thoughts,

Rick

.

Rick, I finding the reading to be enjoyable not that I believe the bs but I really like the 13% grade at 30 mph he has the ISB out preforming a 625 hp C-15 or the 60s.
Even the larger ISL Cummins was junk in a bus Vanhool tried those without success for a few months, you need to buy a ISB then Eisenhower tunnel would be no problem for you  

 


good luck

.

.

Cody, why waste the time I thought the guy maybe on to something till he got to end a 13% grade with a 34,000 lb bus at 30 mph my 5 year old grand child could figure that wasn't going to happen I am gone from this one   



good luck

Clifford,

Eisenhower tunnel isn't a problem I just go around it ;D or I sit back and take about an hour and a half of people flipping me off wiyh a big fat smile on my face because I can't possibly go fast enough to make them happy!!

Cody,
I am not trying to discourage "new" thinking I'm trying to encourage a bit more dialogue here. I think it's pretty apparent that  "I'm set in my way, all telling, rarely listening" type discussions rarely end well in the long run here. Circusboy comes to mind. I for one would love an alternative to our current options horsepower wise bur there's talking and then there's doing and the too rarely run parallel. How many unforeseen problems have each of us encountered when doing any modifications to our rigs? How sure were we that we had it all figured out before we started?

Those encounters where reality makes a fool of our limited knowledge are the very things that temper the way we approach those that visit this place. Folks that speak in absolutes here based on anything other than hands on experience (either their own or collectively) tend to blow in here, cause a bunch of arguments and leave as fast as they came.

If I crossed a line I'm sorry but we have had quite enough drama this year for my liking I was just trying to keep another blowup from happening.

And I'm not joking Roy that if you find a realtime, where the rubber meets the road alternative to our low HP blues, I for one will get my checkbook out
Didn't mean any disrespect,
Rick

.

Cody,

Is it possible? I'm not sure but it isn't a fact either until it's proven in a chassis. So until we see it driving up a 13% grade at 30 mph it is a theory and that's why I was encouraging dialogue rather than monologue. I have to say once again that as a group I have never seen evidence that we are all closed to research and progress here in fact I've seen alot of forward thinking concepts become reality here. However, I have never seen an ISB even remotely considered for a serious repower here and I have also seen no evidence that it's ever been actually done to a 40 foot 34000 lb bus so until it's proven in the real world, saying that it's not a proven fact is not closed minded.

I was encouraging Roy to show us not just tell us and it certainly didn't seem any more matter of fact than his passionate belief that it can be done and anyone who thinks it can't would still be driving steam locomotives. That is a quote from Roy in an earlier post BTW.

Cody, I'm surprised every time you voice a feeling that you feel we are the "new idea police" here, I just disagree that's all.
I am basing that disagreement on the very thing I am kindly asking Roy to provide. By experience.

This kind of discussion in the past has rarely if ever led to a good result. It usually ends up being locked by the moderators.

I do not know for a fact that the ISB is capable of Roy's claims but I'm pretty darn sure about how our board reacts as a group to monolgue type discussions and it's not very well

I am joining Clifford in the "I'm done with this" section
Rick

I don't have a problem with the math at all.  I've known for many years that power is what does work, and gearing to allow power to be applied appropriately is what you do when to build a power train.  While I still don't think that an ISB is a great choice for an MC-9, it's not because I don't think it has appropriate power.  I think that the configuration above would out-perform an 8V-71NA in bus tune, no doubt in my mind at all.  I think that it would not out perform an 8V71TA, with 370 hp at a governed 2100 rpm, capable of well over 400 at 2500 rpm, and 243 hp and peak torque of 1064 ft lbs at 1200 rpm.  It may or may not get better fuel mileage, I would bet that the ISB fuel curve gets pretty stiff at 3000 rpm.  

Here is why I don't think it would be a great engine for a bus.  Transmission - probably not strong enough to push that amount of torque against that load reliably for hundreds of thousands of miles.  Engine - same thing, in a truck application it will be called upon to deliver max power, max torque far less often, and for far less time duration than the same engine in a bus.  For example, full throttle up a hill for 10 or 15 minutes, what will the engine and exhaust temps look like?  I have no idea, I don't think they will be great.  Gearing - postulating a 5.88 diff ratio in the rear axle of an MC-9 is one thing, actually getting one may well be another story.  I don't know,though.

I don't have a problem with the idea, I just wouldn't choose that route myself.  I continue to think the ISB is one of the great engines, though.

Brian

.

The math needs to include inefficiencies & losses to be represenative of real world conditions.

The Caterpillar booklet "Understanding Coach / RV Performance" showed some interesting losses, like their 500 HP motor running at max rpm required 62 HP to drive the fan. Then there is the rolling resistance of the vehicle. Those are the biggest omissions.

In order for an experiment to produce usefull meaningful data, it needs to be well thought out. . .

Simple minded wishfull thinking isn't usually the most successful way.
Neither is ignoring or failing to understand or investigate the reasoning behind current standards


Why not combine it with a "water to gas" system & really show the world how it's done?  ;D

Cummins ISB 6.7 liter for motorhomes is currently rated at 360hp @ 800lb/ft torque.  Considering the 8V-71N with N65 injectors is rated at 304hp @ 800lb/ft torque, the hastle of changing the engine over is just not worth it.  Granted, you might get 1-2mpg better, but that improvement in fuel mileage would take a long time to see any advantage.  Better you either turbocharge the 8V-71N (I know personally that that works extremely well) or go with the larger ISC or ISL (same block) for a maximum of 450hp @ 1200lb/ft torque.  THEN you'll have some performance.  Good Luck, TomC

plus another 10,000 pounds of sand bags and a 10,000 lb trailer.

Quote from: RoyJ on October 28, 2010, 10:28:13 AM

Quote from: kyle4501 on October 28, 2010, 08:20:14 AM
How happy do you think arl will be if his 'freshly tuned to 400 hp' takes a dump after just 40,000 miles?
I know there are no guarantees, but the light duty ISB is definitely more prone to failure than a heavier built engine.

Care to explain why the ISB would take a dump at 40k miles?

Didn't say it would, just asked how one would like it if it did.
I do feel it is likely the ISB at 400HP would have the lowest reliability of the engines mentioned.

As to why it would fail sooner:
Driving style for one thing. A lighter motor traditionally doesn't tolerate 'abuse' as well as a heavier built engine. This is purely cautious speculative opinion based on personal experience & education.
(edit to add) Or lack of education.

After reading all of the post I have to put in my part.
I come from the school of hard knocks and only repeat what I know for sure.  When you hear about a engine going bad like Jim's did it doesn't mean that all the series 60 are going to blow up at 650,000 miles.   For no reason that any of us know any engine can fail with a short life.
This is what I do know for sure, a friend has a coach with the ISB that has had two engines lock up in 180,000 miles. The second engine was rebuilt by Cummins in Mexico.
Another friend is in the process of rebuilding his 8v71 and has already spent over $6,000 on parts alone. He did have to buy two rebuilt heads, but most of the time you will find they have cracks when you need a rebuild.  The parts were not DD they were after market and cost about half of what DD charges.
I have rebuilt one 8v71 in my Eagle, replaced it with a 8v92 then a series 50.  Sure wish I had not done the 8v92, but love the series 50. I just make a big change in the series 50 that will more than likely shorten the life of the engine, but it sure runs good at 375 HP. Only time will tell, but if it goes bad I'll put another one back in for less than a rebuild on a 8v71.
Jack

back to the original post: $ wise it is less expensive to go with a engine currently being used in the bus transportation industry.Most Cummings and 4 stroke Detroit's would be the less expensive..50 and 60 series Detroit's are plentiful and have a pr oven tract record in the industry..If you want to be the one to experiment do what you want..let us know the results..My choice for present project was a 60series 12.7 liter with a 10 speed Eaton autoshift with the stock 4:56 rear end..36,000 lb coach. I had no drivetrain at all so got to select what I felt was best and most dependable for me..nice thing about this hobby do it your way!  Bob

Detroit Series 60 at a conservative 500hp @ 1650lb/ft torque with the 10spd Autoshift (with clutch pedal) makes for an excellent setup.  Granted the Autoshift is not as fast off the line as the Allison (not by a long shot), but your fuel mileage will be about .5-1.0 mpg better.  With the 4.56 rear end and 12R-22.5 rubber (485rpm), your overdrive cruise rpm will be- 1614 @ 60, 1749 @ 65, 1883 @ 70 & 2018 @ 75.  We gear the big trucks for 1600 @ 75, which I would lower to 1500 @ 75, which would translate into a rear end ratio of 3.38.  Then you'll get max fuel economy.  Good Luck, TomC

Roy,

If you don't mind my asking what year is the school bus you drive.

Thanks

Don

Wow, I see that Cody pulled all of his comments before I read them.  That kind of sucks and does not fit my image of good contribution.  Oh Well.

Wanted to add a couple of comments.  First about the loss of my first Series 60.  The engine did not blow.  It had a lot of damage (broken head bolt from heat, and some cam scoring (also heat related).  The "failure" was that the liners sank into the block and let the combustion pressure and gases/heat get into the wrong parts of the engine.  As I look back on it, my inspection of the truck it came out of and a couple of other things leads me to believe that it did not have great service towards the end of its life. I suspect they used automotive antifreeze as there was significant cavitation damage on the liners.  Even with all of the damage, the engine ran fine and got me home with no problem (other than blowing antifreeze out the surge tank).  I had no clue that there were some pretty drastic things going on.

Next, let me comment on HP and Torque.  My current engine is set at 470 HP and 1650 ft pounds.  Even with 10 speeds, it does not race up the hills of Kansas and Missouri (they have some pretty good hills).  In the Colorado mountains, I am in the slow lane with the trucks.  I can go faster than they can, but I don't have the power to pass them in a timely manner so that the folks who pay more taxes than I do can use the highway as their personal race track.  It does not bother me that I have to fall in behind the slower trucks, the scenery is great.  BTW, I am at about 46K with the 9.6K service truck.

I don't have any information to say that the ISB will not do a reasonable job in a lighter bus.  As has been pointed out, it is/has been used in some motorhomes.  However, when we start talking about 40 foot buses, they are often over 35K and some well over that.  Then you add a toad.  The Series 60 and other class 8 truck engines are very heavy duty and are designed to run all day under heavy load for 500K or more miles.  The have very strong blocks, cranks, and cylinder liners.  I don't think the ISB is that kind of engine.  Yes, you can modify them to get some pretty good HP and Torque, but in an RPM range that probably requires some unique gearing that is not readily available for buses.

Bottom line my big axx Series 60 is just about right and anything smaller would not be fun to drive with my weight.  

BTW, some Flxible folks use the ISB and that is probably a good fit.

Jim

Whoa, some of you guys take things way too seriously. So I'll try to clear up my intentions: in no way am I trying to disrespect any of the senior members here, I have my uttermost respect for these guys and their experiences.

That having been said, some of you also need to loose the attitude of "this guy's new, he must be an idiot and doesn't know what he's talking about".

Quote me where I said anyone (TomC or anyone else) is "wrong". I didn't. I simply defend my own opinions with calculations. I was disagreeing when others simply pointed out that I'm wrong, without any facts or scientific argument. If you feel that's rude, then well, I wouldn't know what to say.

Quote from: Don Fairchild on October 28, 2010, 03:39:39 PM
Roy,

If you don't mind my asking what year is the school bus you drive.

Thanks

Don

Don, the one I've been referring to all the time is a 1996 Thomas MVP, with a 5.9 pusher. 12V, P7100 pump, so less than 250 probably.

It has a GVW of 18,500 kgs (40,000 lbs). But following US axle rules, probably no more than 36,000 lbs.

Quote from: RickB on October 28, 2010, 12:32:33 PM
Cody,

Is it possible? I'm not sure but it isn't a fact either until it's proven in a chassis. So until we see it driving up a 13% grade at 30 mph it is a theory and that's why I was encouraging dialogue rather than monologue. I have to say once again that as a group I have never seen evidence that we are all closed to research and progress here in fact I've seen alot of forward thinking concepts become reality here. However, I have never seen an ISB even remotely considered for a serious repower here and I have also seen no evidence that it's ever been actually done to a 40 foot 34000 lb bus so until it's proven in the real world, saying that it's not a proven fact is not closed minded.

I am basing that disagreement on the very thing I am kindly asking Roy to provide. By experience.

First of all, Rick, I've stressed over and over again by now, about the tens of thousands 40 foot school busses, grossing mid 30k lbs, running around our nations. Do you not consider that "real world"?

Second, a little personal background here:

My main career is Mechanical Engineering, which means all my work is revolved around unproven facts, unknowns, and no experience. I'll stand by my origional quote: if everything has to be known by experience, we'd still be in steam trains, or worse, ox carts.

Why do you think the biggest advance in recent engineering is simulation? Everything from complex fluid dynamics to solid structures are simulated on computer generated mesh data. Why? Because no real world experience exists!

No, I do not have real experience with an ISB in an MC9, but what I did provide was cold, hard, basic calculations. Numbers don't lie. As busnut, we represent a very unique market - using commerical duty vehicles at a recreational duty cycle (a word I emphasis all the time). The reason no one puts an ISB in a coach, is that all coaches are designed for commerical service life. We're not after that.

 Lol It's always fun on paper, til someone gets hurt  ;D



Paper cuts suck ;D

Quote from: luvrbus on October 28, 2010, 11:57:54 AM
Cody, why waste the time I thought the guy maybe on to something till he got to end a 13% grade with a 34,000 lb bus at 30 mph my 5 year old grand child could figure that wasn't going to happen I am gone from this one   



good luck

So you ask for a real world dyno, I provide you with one, and even proceed to give some calculations based on it, and then you reply with this comeback?

Why don't you point out where I'm wrong instead?

Before you say numbers and calculations don't mean anything, consider this: my last job in engineering was fuel cell design. The larger stacks we designed were used for - you guessed it, buses.

How do you think we related a random output number from the fuel cell, say - 178 kw, to real life performance of the buses? All calculations, most on the good'ol Microsoft Excel. I was one of the main engineers responsible for performance simulations. Everything from uphill, downhill braking, passing manuver, to top speed, was pre-calculated before any trials were run.

Quote from: bevans6 on October 28, 2010, 12:33:28 PM
I don't have a problem with the math at all.  I've known for many years that power is what does work, and gearing to allow power to be applied appropriately is what you do when to build a power train.  While I still don't think that an ISB is a great choice for an MC-9, it's not because I don't think it has appropriate power.  I think that the configuration above would out-perform an 8V-71NA in bus tune, no doubt in my mind at all.  I think that it would not out perform an 8V71TA, with 370 hp at a governed 2100 rpm, capable of well over 400 at 2500 rpm, and 243 hp and peak torque of 1064 ft lbs at 1200 rpm.  It may or may not get better fuel mileage, I would bet that the ISB fuel curve gets pretty stiff at 3000 rpm.  

Here is why I don't think it would be a great engine for a bus.  Transmission - probably not strong enough to push that amount of torque against that load reliably for hundreds of thousands of miles.  Engine - same thing, in a truck application it will be called upon to deliver max power, max torque far less often, and for far less time duration than the same engine in a bus.  For example, full throttle up a hill for 10 or 15 minutes, what will the engine and exhaust temps look like?  I have no idea, I don't think they will be great.  Gearing - postulating a 5.88 diff ratio in the rear axle of an MC-9 is one thing, actually getting one may well be another story.  I don't know,though.

I don't have a problem with the idea, I just wouldn't choose that route myself.  I continue to think the ISB is one of the great engines, though.

Brian

Brian, I don't disagree with what you say at all. I never claimed the ISB implant was perfect, or I'd be rich by now... Every solution has its share of problems, and transmission / gearing as you point out, was perhaps my biggest two worries.

Now, my own bus is a 25,000 lbs 35 footer, so the transmission would handle it without a problem. But even then, I'd beef it up with better converter and valve body, in addition to a huge fan blown cooler. The 5.88 is a big issue. I've considered axles from class 7 trucks, many of which have ratios of mid 5's. Coupled with low pro 22.5 tires, I might get close to 5.88 effective ratio.

The engine EGT and coolant temp shouldn't be an issue, as I'm not making internal changes such as huge injectors. In fact, the head load would reduce without the emmisions garbage. I also believe the cooling capacity of an MC9 is many times larger than a Dodge pickup.

About the continuous full power issue, this is what I was referring to by duty cycle. I highly doubt an MC9 would require constant 400 hp, considering the MC102 I drive at work (charter duty) gets by just fine at 290 rwhp (360 crank hp). Even then I'm not flooring it all the time.

But you make a good point. An ISB swap in a coach is definitely not for people that just want to step on it. Like any other modded hardware, it would require constant monitoring with proper gauges, and a restrained right foot.

Quote from: kyle4501 on October 28, 2010, 12:39:06 PM
The math needs to include inefficiencies & losses to be represenative of real world conditions.

The Caterpillar booklet "Understanding Coach / RV Performance" showed some interesting losses, like their 500 HP motor running at max rpm required 62 HP to drive the fan. Then there is the rolling resistance of the vehicle. Those are the biggest omissions.

In order for an experiment to produce usefull meaningful data, it needs to be well thought out. . .

To be fair, the dyno I showed is measure at the WHEELS, which is post losses (drivetrain, fan, alternator, and any other accessories).

The rolling resistance is a very good point though, and I admit, I forgot to include it. Typical tire rolling resistance is 0.015 for a bus, and aero forces for an MC9 size coach is almost negligible at 30 mph, it's only 35 lbs.

So, 34,000 lbs * 0.015 = 510 lbs, add 35 = 545 lbs.

From my origional numbers:

4472 lbs thrust, - 545 lbs = 3927 lbs net thrust.

3927 / 34000 = 11.5 % grade @ 30 mph

Still pretty respectable.


If anyone see any other error, please point them out to me. But don't just say your 5 year old grandson, or 200 year old great grand aunt knows better than an ISB pushing 34,000 lbs...

Quote from: kyle4501 on October 28, 2010, 12:39:06 PM
Neither is ignoring or failing to understand or investigate the reasoning behind current standards

Again, current standards are all designed for commercial duty cycle. Name one OEM that design for busnuts?

RV manufactures seem to agree with me, if they tune an emissions choked ISB to 360hp (easy 400hp without emmissions).

I remember reading on CCJ a year or two ago of a front-engine Blue Bird (probably a TC2000) with an ISB  -  it completely stalled out while trying to climb one of the steeper climbs in the Sierras with a full load on board.   I'm assuming its engine was at the ISB's standard school bus 190 HP setting, and it probably was grossing in the low 30,000 pounds, but it literally could not get out of its own way climbing a grade that older Crowns and Gilligs could manage with no problem.   The difference of course is its torque (or lack thereof).

Yes, I know that more powerful settings of the ISB are being discussed here, but real world experience shows that small engines in heavy vehicles don't always work so well.   That's one reason why some school districts, especially those in the Sierras and Northern California, prefer keeping their thirty-year old Crowns with big-cam Cummins 855s instead of buying brand-new disposabuses with ISBs that CARB is forcing on them.

John

John, like you pointed out yourself, we're talking about a 400hp tune ISB here.

There's a HUGE difference between 190hp and 400hp. The school bus I drive is also pretty slow once loaded, and that's low 200's hp. Low torque can always be made up with gearing, low hp is low hp, cannot be made up with any simple machinery, or you'd get free energy.

There are some 40 foot hybrid transits out there with ISBs, but that's with a big electric motor assisting.

Quote from: rv_safetyman on October 28, 2010, 06:17:05 PM
BTW, I am at about 46K with the 9.6K service truck.

I don't have any information to say that the ISB will not do a reasonable job in a lighter bus.  As has been pointed out, it is/has been used in some motorhomes.  However, when we start talking about 40 foot buses, they are often over 35K and some well over that.  Then you add a toad.  The Series 60 and other class 8 truck engines are very heavy duty and are designed to run all day under heavy load for 500K or more miles.  The have very strong blocks, cranks, and cylinder liners.  I don't think the ISB is that kind of engine.  Yes, you can modify them to get some pretty good HP and Torque, but in an RPM range that probably requires some unique gearing that is not readily available for buses.

Jim

Jim, with a bus at 46k lbs, I wouldn't even remotely think about an ISB, regardless of duty cycle. My assumption of a 34,000 lbs converted MC9 would be the absolute max I'd put an ISB in, simply because that's what hot shotter gross with Dodge Rams. The ISB plan was origionally for my 25,000 lbs bus, which can go up to 30,000 with a toad and heavy gear.

I never doubted that a Class 8 engine, bigblock (ISX, S60) or smallblock (ISM, C13) would be much more durable than an ISB, hp for hp. But that's the exact reason why I wouldn't want one in an RV bus - they're too durable. You pay for the durability even though you'd never use it.

I drive my bus no more than 6k miles a year (and probably most people here as well). At that rate, I'd never wear out a 500hp S60 engine, or even the ISB.

Quote from: TomC on October 28, 2010, 12:39:31 PM
Cummins ISB 6.7 liter for motorhomes is currently rated at 360hp @ 800lb/ft torque.  Considering the 8V-71N with N65 injectors is rated at 304hp @ 800lb/ft torque, the hastle of changing the engine over is just not worth it.  Granted, you might get 1-2mpg better, but that improvement in fuel mileage would take a long time to see any advantage.  Better you either turbocharge the 8V-71N (I know personally that that works extremely well) or go with the larger ISC or ISL (same block) for a maximum of 450hp @ 1200lb/ft torque.  THEN you'll have some performance.  Good Luck, TomC

Tom, I definitely wouldn't pull out a perfectly running 8V71 and put in an ISB. But in the OP's case, where the engine is not running so well, and it's a choice between a rebuild or engine swap, then it makes sense.

I'm also not implying the ISB would run circles around the 8V71, but rather, that it's adequate as a replcement. At high elevations however, the ISB would shine.

Yes, I have read your past experience on turboing your 8V71, and it has inspired me to design a (very) low pressure turbo setup for my little 6V71 4V N70. I'm thinking 3 - 5 psi, with no engine internal changes, using two HX35 turbos. I'm satisfied with my power at sea level, but it falls flat above 4000'. The ISB is for my engine wears out.

I like to see discussions of out of the box thinking, they sometimes lead to something innovative.  Thomas Edison was a big believer in that.  He once said "I can tell you 10,000 things that don't work."

However I do believe that the life span of an ISB in a MC-9 would be severely limited.  I am not a diesel engine expert nor am I an engineer, but there is one point to consider while talking about duty cycle and RV use of a highway coach such as the MC-9 that I haven't seen in this discussion.  In my opinion, the more important duty cycle consideration is about hours/miles of continous operation in a steady run than hours/miles per year.  That is where a heavy duty engine shines.

A school bus in school service will typically operate about 2-4 hours in the morning, rest for a few hours and then 2-4 hours in the afternoon.  During that time it will typically be ranging through its RPM/Power range frequently.  On occaision they may travel 4-6 hours to an out of town game.

There are quite a few folks here that take cross country trips in their buses, driving 8 or more hours per day using over 220-250HP sustained output.  There are some that push 12 hour driving days.  And there are at least a couple that team drive their bus 24 hours or longer virtually continous including up and over the Rockies.  I believe that kind of continous high output use pushing a 34,000 or more load would result in an early death for the ISB.  I do know that in a lot of factory RV's they often end up needing overhauls in 50,000-70,000 miles.  I don't know how many of those are ISB's.

I think most MC-9 conversions end up weighing 35,000+ and they will often pull a toad that weighs 3500-5000. The GVWR for a MC-9 is 38,000 I believe.  My RTS currently weighs 32,000 and my toad weighs 4100.  And my RTS doesn't have the large cargo bays, extra large tanks, generator or large house battery bank.

Quote from: RoyJ on October 28, 2010, 09:25:24 PM

Quote from: kyle4501 on October 28, 2010, 12:39:06 PM
Neither is ignoring or failing to understand or investigate the reasoning behind current standards

Again, current standards are all designed for commercial duty cycle. Name one OEM that design for busnuts?

RV manufactures seem to agree with me, if they tune an emissions choked ISB to 360hp (easy 400hp without emmissions).

About those RV manufacturers, most use the minimum they can get by with in order to cut cost & last past the return period. Isn't that why most of us are here? To have something well above 'minimum'.

Dad has an Airstream MH built on a Freightliner chassis with a 330HP CAT (all as it left the factory & no mods at all). He can't use full power for anything except acceleration (& that is time limited too) because of overheating - they didn't install a radiator big enough to handle the engine's installed HP. Hmm, what does that say for one of the most respected RV manufacturers design intent?

The 460 in Dad's van has ~200k miles on it, ~100k pulling a 8,000# Airstream trailer. The same 460 in a motorhome seldom lasts past 75k miles before a rebuild is needed. I propose the reason is duty cycle - the van has periods of 'rest' where the MH is in constant duty.

While your math may show it will work, the preponderance of real world evidence leads to a different conclusion.

For long term considerations of time & $$, my bet is with a used heavy duty engine of similar type that is currently in the bus. While not guaranteed, history indicates a higher success rate or put another way, more bang for buck.  ;D

But, feel free to "roll your own".

Roy J.    First of all I object!    Don't knock steam power..still the most bang for the buck..also my son is a engineer and works on drive systems for ships..in the end still steam.power plants still steam.no matter fuel source..still steam---we have two antique steam engines a 1905 Huber and a 1925 KeckGonnerman 19hp. we run the Huber 16hp( this boiler hp) .regularly 105 yrs old.we take scrap from the saw mill and burn in the boiler..recycle--Enjoyed your post!! and be prepared to get any point challenged..And by the way the three trucks my cousins run are not week end toys..to put 60,000 in a little cummins you got to get some of that back..Both John and Tammara are engineers one Mechanical and one Electrical .Later 20's brother and sister and their old Dad still helps with the work..They think outside box also! keep it up!

I enjoyed this thread immensely.  I've had many conversations with people who confuse the relationship between torque and power, which are two sides of the exact same coin separated only by time (RPM).  And out-of-the-box thinking is always a challenge to wrap your head around.  On the "other" side of my travel effort I run a Dodge 2500 pickup with a Hemi at 18,000 gross weight, and so I know that power with appropriate gearing can work wonders - it's a ton faster at that load than my bus is, in any circumstance, and my bus is only around 26K lbs. 

Anyway, good to consider another way to kick the can...

Brian

Yes, I removed some of my posts, some wern't appropriate and some wern't relevant, and some should take note of the action.  I'd like to welcome roy to the board, I'm pleased to see somebody that can write a mathamatical equation that I can read and understand instead of just saying something can or can't be done, here are the numbers, prove them right or wrong, everything starts with numbers regardless of what a person feels comfortable with, it all begins with numbers. I've always said that I don't understand metal, it confuses me, but equations I do understand and it's nice to see somebodies thoughts backed up by the math.  People have to wake up and realize that our beloved 2 strokes are doomed, if anyone has read the drivel that our leaders have signed onto in the international 'green' world, our 2 strokes are doomed.  We have to start to think about what is coming next and the smaller lighter duty engines may be all that will be allowed in our private rigs in a short time, Don Fairchild is already seeing what is being forced on us and is working to provide a remedy but the next wave is already been signed and is waiting in the wings, and the wave after that.  I know that many feel comfortable in their greasemonkey clothes but take a moment and climb out from under your beloved 2 stroke and do some reading, read what obama has signed onto for us in the international market, read up on exactly what a carbon footprint is and then take a good look at your engine compartment and don't expect to be grandfathered in, has anyone seen the required fuel mileage figures for the next few years?  We need a few more actual engineers on this board.

At least for now in California, RV's are exempt from smog laws.  But-when that time comes to switch over, I will do the engine swap on my truck's Caterpillar 3406B to probably a Cummins ISL with 450hp and 1250lb/ft torque.  Hopefully by that time there will be an assortment of crashed trucks with 2010 engines available.  At least for commercial trucks and buses-the law reads for California: that by 2023, all trucks and buses in or coming into California must have 2010 certified engines (ones running with Urea, or DEF [Diesel Exhaust Fluid], or BlueTec {by 2023 International will have a similar system}).  Still-RV's have not been mentioned.  Good Luck, TomC

What do need with more engineers on the board Cody Cummins Engine has 1000's that designed that engine, check the Cummins sites they will tell you what the souped up 5.9 changed to a 6.7 EGR is capable of doing or if that doesn't work just go to some of the Dodge sites.
I have a friend in Houston VP of Southern Plains Cummins read this post he said go for it and he will see you in about 30,000 miles and bring plastic or your check book it will only cost you 15,000 without the Bosch fuel pump



good luck

What we need are more actual engineers on the board and not just people that would like us to think they are, whether you like it or not our 2 strokes are going to be history in the not too distant future, we all have friends we can quote, thats nothing new, what we need are fresh ideas to cope with what is being discussed in circles that we can't access.  Some engines won't be appropriate for weight classes that are extreme like a 46K bus pulling a 10K vehicle up a verticle wall but for many of the buses in use now that range between 25 and 35K there are choices that might be well concidered. Anyone that thinks that the emmissions rulings are going to just go away are in for a huge wakeup, several states are looking at what california is doing and thinking beyond that.  Bush set the stage and obama is bringing out a whole host of players, look at what he's signed onto in the international settings, and he's not afraid to use his pen to bypass congress thru executive orders just as bush did. It's your choice if you want to ignore whats going on around you but at some point we will all have to realize that there is a movement going on that we will have to cope with or at least adapt too and some new ideas arn't a threat to any of us.

Cody, I  know of 6 engineers here on the board you do battle with 2 all the time lol so they don't waste their time on posting the facts, knowing Jim he just reads a shakes his head he is not going to waste his time he has tried for years only to have it turn into pissing contest.


good luck

Can you post the names of the 6 engineers and their PE registry numbers please?

No doubt that possible future restrictions should also be considered. Environmental impact awareness should also be a part of any action.

That is easier said than done sometimes.
Which will have a smaller carbon footprint will only be a guess based on past history - which we should all know "past performance does not guarantee future results".

In the past, we weren't a disposable society. We used to be able to buy brushes & bushings (off the shelf at any parts store) to rebuild a starter, now it is difficult to even find a listing for those items at most parts stores.

Even if the 2 strokes will be mandated out of use (by law or code) in 12 years, is it better for the environment to scrap them all out now & fave the impact of having to build new replacements? I don't know, but I think it is something that has to be determined on a case by case basis.

I have a feeling that the next 10 years will bring about some great innovations that will be of great benefit. Some will also be of great burden with nothing good.

The original poster was looking for re-power suggestions & he got several. One can't make an informed decision without seeing all sides. As was pointed out, changing from 2 stroke to 4 stroke takes more time than he wanted to spend & would cost much more than "fixing what he has".

Changing to a custom gear ratio isn't for the faint of heart either. . .

Sometimes, a little better understanding of the bigger picture makes it easier to live with the shortcomings of our less than optimum toys.  ;D

Quote from: cody on October 29, 2010, 09:07:54 AM
Can you post the names of the 6 engineers and their PE registry numbers please?

A PE registration number does not make one an engineer.

Passing the test wasn't difficult.  ;D
Earning a masters degree in engineering is much more mentally taxing.  ::)

Staying out of pissing contests is another thing entirely.  ;)

Kyle, that was a remarkable post and one that is important for us all to read and take to heart, your right, we don't know what the future regulations will entail, but at the same time we can't just bury our heads and wait, the future starts today and we need to explore all available options, just because it doesn't make mechanical sence to someone thats turned a fair share of wrenches doesn't make the entire concept wrong.  Take into concideration what we already know, first is that the green community wants the 2 strokes gone, as a matter of fact they want almost all gas or diesel engines gone and be assured they have the money available to them to make a lot of noise.  The world is changing around us and the more options available regardless of a persons convictions are, the better off we all are.

Yes, a PE registry number does make an engineer, registered engineers often have people working for them, that doesn't make those people engineers, lawyers often have paralegals and clerks working for them but that doesn't make those people lawyers and the people that work in a doctors office arn't always doctors.  I have engineering degree's but I'm not an engineer, nor do I claim to be although I do understand the process.  If a person is accredited and licensed then I applaud them for taking the time to do more than make the claim, many people here may have worked for engineers but that doesn't magically turn them into a PE tho they might be qualified, it reguires the documentation to sign on the bottom of the page.

I respectfully submit that it is not the green community that you need to worry about.  Who profits when an old technology is banned except the providers of the new technology?

The old two strokes have no commercial viability but I doubt very much that they will ever be banned from non commercial use.  There numbers will continue to dwindle until there are just not enough of them left for the government to worry about.

I'd like to ask Don to give his thoughts on the 2 strokes future, he is neck deep in the problem now and i'd very much like to know what he envisions 10 years down the road.

Quote from: cody on October 29, 2010, 09:45:07 AM
Yes, a PE registry number does make an engineer . . .  

from:
http://www.merriam-webster.com/dictionary/engineer (http://www.merriam-webster.com/dictionary/engineer)

Definition of ENGINEER
1: a member of a military group devoted to engineering work
2obsolete : a crafty schemer : plotter
3a : a designer or builder of engines b : a person who is trained in or follows as a profession a branch of engineering c : a person who carries through an enterprise by skillful or artful contrivance
4: a person who runs or supervises an engine or an apparatus

Hmmm, No mention of registry.
Looks like someone needs to straighten those buffoons out. . .

Unless you are confusing a Professional Engineer with an engineer.

Hey y'all.  This is awesome!  Really.  

At first I was reticent to post because I figured everyone would yawn at the newbie asking a dumb question.  88 (mostly:) relevant and courteous replies later I'm glad I did.  There's been a LOT of great info shared here -which will be useful for years to come.  RoyJ chimed in with a really provocative concept, and has taken it on the chin and still stood his ground with real numbers - thanks RoyJ.  Others have brought up excellent counterpoints - one in particular about sustained heavy duty operation of an RV/Coach over many hours or even days is pretty compelling for leaning away from the ragged edge of efficiency.  So there are both sides to consider, and both are VALUABLE.  Let's keep treating each other that way  [no, I'm not an egalitarian or a sissy, I just know that humility and honest consideration are invaluable in teams working toward a common goal, in this case the discovery of a better solution to repowering these God-forsaken 8V71 engines  :) :) :) - just having a little fun there !! ]

Now... my problem is I still don't know what to do.  I know it's not all y'all's (I live in Southern KY and the previous is actually acceptable speech here - no matter that it violates basic laws of punctuation) job to solve my problem, and I'm quite sure I could spend time and money  (if I had either) and get the solution without help, but that's stupid when there is very likely someone or several someones out there who already know the answer, or are reasonably close.

Isn't there something BETWEEN an ISB and an ISM?  Based on the discussion (ISB too small, ISM too big) I would think that we could narrow this thing and focus on whatever that is.  I asked a while back about it.

I know almost diddly about diesel engines, but my boys have worked with the Matneys three times now taking ours apart and fixing burned valves, so I know enough about the one I have to say I hate it - passionately... viscerally... loathe that thing.  Just thinking about keeping it makes me nervous and fidgety, even if it is the cheapest route in the short term.

So I'm still hoping beyond hope that folks will grant me extended grace and keep the suggestions coming.  Help this husband and father of eleven move the crew from one place to the next "Singing As We Go"!  Thanks to all y'all VERY MUCH.

warm regards to all,
Alan  [PE License Nos.: KY 26178, NY074491-1, OH 60047]

PS.  On the comment about posting PE numbers for engineers, just because you are an engineer and have a PE license doesn't mean you know anything about diesel engines.  I can't even fix my radio if it breaks.  I can do world-class work in a VERY narrow field, which generally makes me useless for most other things and almost always looking for work.  If I'd known this ahead of time I would have been a doctor :)

All the same, I agree with Cody that folks who really know their equations would be invaluable help here.

Alan, eleven kids? wow you need more help than is available here. lol

You also need more buses that are available here!   ;D

Well I am not a engineer ,doctor or lawyer only the general business degree for me, but I did pay for 2 engineering degrees from Texas A&M ,1 law degree from SMU and 1 DVM from Texas A&M so I know where to get answers paybacks are hell just ask my kids   lol  fwiw the DVM  degree was the killer


good luck

Mine were paid for by the state of michigan, under governor blanchard, he felt that state employees could benefit by continuing education so I was able to get my engineering degree's and one in business administration and one in criminal justice, then governor engler realized I was spending most of my time in the classroom and made me return to work, I had high hopes to be the first state employee to retire from the classroom setting.  The beauty of it all were that I got 4 promotions while still in the classroom, life was good for a while.  Right now I'm paying for 2 medical degrees, one will be a radiologist and the other is now going for her RN, she started as a CNA, then LPN, now heading for RN while I head for broke.  I agree the DVM would be the killer, jamie talked about it for a while before deciding on radiology, for DVM she would have had to go to the university of michigan for it and the cost was an eye opener, with both in private schools now it's hard enough, but I do get some great sweat shirts and t-shirts, the school is Finlandia University and I sent bryce a great FU shirt.

Clifford,

I am impressed. No wonder you were building those big box stores. I knew all along you were one bright bulb....

Alan,

I sent you a PM (personal message). Let me know if you don't get it.

God bless,

John

Quote from: arl on October 29, 2010, 09:57:56 AM
. . . .Isn't there something BETWEEN an ISB and an ISM?  Based on the discussion (ISB too small, ISM too big) I would think that we could narrow this thing and focus on whatever that is.  I asked a while back about it.

Understanding you absolutely loathe & despise your existing engine, I would advise to re-power. No sense in having the bus if you want to kill it.  ;D
That said, with an eye on the available funding, I'd suggest a proper tune up on what you have to minimize the pain & suffering while you drive it 1 more season. During that season, look for the ideal donor truck or bus to be used to provide for your re-power. Also keep in mind that if you increase HP of the engine, you may have to increase the radiator heat rejection capacity. (4strokes seem to reject less heat, but you don't need too many unexpected surprises.) Also during this extra season, keep notes on your existing engine, they will help when it comes time to sell it after the re-power.

When looking for a donor truck, consult local truck wrecking yards & find out what is common vs what is junk. Look for a donor truck you can get the whole engine, transmission & associated gadgets. Make sure the transmission gearing will work with your rear axle ratio. Some garbage trucks have the overdrive gears electronically locked out - they are still there, you just have to reprogram them. Measure the different engines to find what fits most easily.

Another thought on the repower, a mistake I almost made, if you decide on a donor truck for an engine take note on the positioning of the various components, I almost opted for one with the top mounted turbo, while the turbo could have been moved or the floor raised it would have been extra work and extra expense and yes, keep all available documentation.

I stand by my original advice.  Way back on page one   ;D

Your requirements = Modest power, reliable, efficient, automatic, and - critically perhaps - finished by January 2011.  Find a take-out 6V92/740 Allison from another MCI MC-9 and slot it in, and hope it runs better than your current engine.  Why - it's 350 hp, it's more economical (than a trashed 8V-71), it's dead reliable, it's not electronic, it's a dead reliable transmission, and MC-9's came that way from the factory so it's an OEM install.  You could do it in a week.  Or less if you got set up right.

If you want to spend $20 or $30 grand for a four stroke, the Series 50 installs I saw impressed the heck out of me.  But you won't be on the road in January unless you have it done in a pro shop and that puts the price at the high end of the scale.  To some that's a lot of money and sweat equity doing it themselves, to others they just pull out the check-book.  But a lot of people do go that route and brag on the result.

Brian

Quote from: arl on October 24, 2010, 06:27:49 PM
[NOTE:  This is a parallel post to something I put on another bus site.  If that's not kosher, please let me know.  I'm really just trying to get this problem solved, not trying to be a pain.  Thanks!]

Howdy everyone. I'm quite sure you've answered this question many times, but my searches through the archives aren't getting my the answers I'm looking for. If you know of an exhaustive post already done, please point me to it. If you have ideas, please let me know.

I am desperately seeking a solution to the repowering of my existing 8V71 and Fuller 5spd manual to something else. ANything else. I hate that engine. It's loud and sucks fuel and pukes oil. It has no turbo, the tranny has no overdrive. It's killing me one mile at a time and I want to upgrade. It's burned four valves in two years, uses a gallon of oil every 400 miles, and just badly needs an overhaul (which the previous owner said it already had). I'd rather spend the money on some improvements.

SO... what's the optimal engine/tranny combo for repowering an MCI-9 with 8V71? I'm a guy that just wants to get me and my family from point A to point B reliably and as efficiently as possible. I don't need extra horsepower, I don't need fancy anything - well... cruise and jakes would be nice if easily incorporated. I'd like the engine to have turbo and the tranny to be either autoshift or automatic, though this is not essential as me and my kids have learned on this Eaton Fuller 5spd and are comfortable with manual.

Also, where are salvage sources for these powerplants?  Wrecked trucks, fleet sales, etc.?  Any help is greatly appreciated.
Many many many thanks in advance for your expert and thoughtful help getting me back in service.

I just went back and looked at your first post in this long thread.  I am certainly not an expert, but would suggest a couple of things.

A gallon in 400 miles; engine is shot or just the wrong oil. Burning valves would suggest that you may be lugging it.  If it literally stinks, it may well be worn out or badly out of tune.  A good running 8V-71 actually smells kind of sweet.

If I understand you correctly, you are not into big expensive projects, don't really need a lot more power, and while you would prefer an automatic, you can live with the stick.

If the previous owner actually did do some kind of overhaul, it may just be a matter of running the rack and changing the oil.

I suggest an evaluation by a good two stroke guy and then either overhaul what you have or replace with a similar engine.  While it will never be a hot rod, that engine has driven a lot of buses for millions of miles, and properly set up can be a pleasure to drive.  My experience is with Eagles, but the same basic drive train.

On the other hand, if your check book is too fat to fit in your back pocket, there is nothing you cannot do as far as a repower.

Howard Best did a series 50 re-power on his bus. He has also done several re-powers on other people's buses, so he has quite a bit of experience in this area.
He is pleased with the results of his, but he did say he wouldn't do it again. I got the impression the cost to benefit ratio wasn't as good as expected.

Brian has an excellent point to consider with the 6V92 - would be the most bang for buck & could quite likely be done 'in house'.

arl needs to determine if his existing motor is shot or out of tune. Could make a big difference in his satisfaction with a re-power - if current motor is making a good 300hp & it is too slow, I doubt 350hp would be worth the trouble - If current is below 200hp & can be brought up to nearly 300 - his hatred of the motor may subside. . . .

I replaced a motor one time due to persistant low power - turned out to be a few problems elsewhere & not the motor's fault at all. Live, learn & share the knowledge gained.

Mike Leunstanski (sp?) on the board did the cummins transplant in a mci.seems to be very happy with it.M11( I think.).engine source was a transit bus..can be bought reasonable with some with low mileage motors.2or3 thousand dollars and you have all the parts to make change and maybe 1/2 purchase price in scrap to sell..I've met mike and seen his bus .very nice work and great guy.

Quote from: robertglines1 on October 29, 2010, 11:57:24 AM
Mike Leunstanski (sp?) on the board did the cummins transplant in a mci.seems to be very happy with it.M11( I think.).engine source was a transit bus..can be bought reasonable with some with low mileage motors.2or3 thousand dollars and you have all the parts to make change and maybe 1/2 purchase price in scrap to sell..I've met mike and seen his bus .very nice work and great guy.

Mike used an L10, I have his previous engine (8V71) in our bus. He also used the 6 speed automatic transmission from the transit and changed to a different rear-end ratio.  He did a beautiful installation including custom motor mounts.  Jack

Cody;

I will respond in another thread this one is getting long and what i have to say may take up a few pages.

I will respond here with I am not an engineer ( I had a hard time spelling it,thank god for spell check) nor do I claim to be one. They had to kick me out of high school they were afraid that I would stay around till I was an old geezer, and when I tried collage the girls were to purdy and the skirts tow short so that didn't work either.

The only thing I have to fall beak on is I have been turning wrenches for a living for almost 45 years.

Don

Also,

Arl is it you don,t like two-strokes or that you have had terrible luck with yours. Is it you that has the eleven kids, you weren't a cub or boy scout were you. You need to learn how to tie knots better then that. Man I don't need the first two lines of a hockey team living my front room.

Don

Don he shoulda took a ride on your little hot rod motor huh! ;) ;D

Don
The BEST reply so far.

Quote from: arl on October 29, 2010, 09:57:56 AM
Isn't there something BETWEEN an ISB and an ISM?  Based on the discussion (ISB too small, ISM too big) I would think that we could narrow this thing and focus on whatever that is.  I asked a while back about it.

That would be the ISL, and slightly more ancient ISC. An ISL would make 400hp in RV duty cycle trim, while 320 hp is more common in high duty cycle applications (primarily transits).

Alan, the reason I like the ISB combo so much is cost. Whereas ISL, ISM only appear in commerical vehicles and RVs, ISBs are in millions of Dodge Ram pickups. This makes engine, transmission, parts, and aftermarket availability much better compared to the larger Cummins.

Now, I don't know the exact weight you'll be hauling (and towing), so the ISB may or may not be a viable solution for you. It largely depend on how much you're willing to spend. If money wasn't an issue, I would never bother with the ISB either.

More great help.  Thanks folks.

I've been told that a rebuild in my 8V71 will cost 2-3K in parts.

Based on all posts I've read, the ISB option is interesting but without much margin.  We drive 30,000 miles a year, mostly east of the rockies, but could easily find ourselves coast to coast .  We go from south tip of texas to Canada twice a year.   Climate changes, terrain changes, altitude, plains, mountains, we see it all.  So I'm inclined to have a little extra when necessary, which the ISB may or may not provide.  Still on the table, but I'd need to hear more folks with 36K lb coaches using it with satisfaction.

If I can get an L10 with tranny for anywhere near that out of a transit bus or scrap truck does it make sense to go that route?  Can THAT be done in two months for under $8K if we could do a lot of the work ourselves under supervision?

How do I connect with this Mike L. person that did the L10 job and is happy with it?

Would an 8.3 Cummins out of a wrecked Country Coach RV be worth considering?  I don't know anything more about that engine... my friend in Ohio just said it was an 8.3, which seems to make it between the ISB and ISM.  Am I demonstrating my ignorance?

Thanks again for staying with this thing.  

Alan
PS.  Yes, 11 children - all blessings.  We wanted every one of them and they're all great.  We often qet the twenty questions from folks when our family is out and about somewhere.  Inevitably someone will ask the really stupid one... "Don't you know how that happens yet?"  One of these days I just wish my wife would put on her shy face and and quietly whisper "Yes, that's the problem, we're addicted."   just so we could see the person's response!  She's WAY too proper for that though - usually.

OK... back out this rabbit hole before it gets crazy.  Stay on track y'all!

Quote from: HighTechRedneck on October 29, 2010, 12:26:44 AM
I like to see discussions of out of the box thinking, they sometimes lead to something innovative.  Thomas Edison was a big believer in that.  He once said "I can tell you 10,000 things that don't work."

However I do believe that the life span of an ISB in a MC-9 would be severely limited.  I am not a diesel engine expert nor am I an engineer, but there is one point to consider while talking about duty cycle and RV use of a highway coach such as the MC-9 that I haven't seen in this discussion.  In my opinion, the more important duty cycle consideration is about hours/miles of continous operation in a steady run than hours/miles per year.  That is where a heavy duty engine shines.

A school bus in school service will typically operate about 2-4 hours in the morning, rest for a few hours and then 2-4 hours in the afternoon.  During that time it will typically be ranging through its RPM/Power range frequently.  On occaision they may travel 4-6 hours to an out of town game.

There are quite a few folks here that take cross country trips in their buses, driving 8 or more hours per day using over 220-250HP sustained output.  There are some that push 12 hour driving days.  And there are at least a couple that team drive their bus 24 hours or longer virtually continous including up and over the Rockies.  I believe that kind of continous high output use pushing a 34,000 or more load would result in an early death for the ISB.  I do know that in a lot of factory RV's they often end up needing overhauls in 50,000-70,000 miles.  I don't know how many of those are ISB's.

I think most MC-9 conversions end up weighing 35,000+ and they will often pull a toad that weighs 3500-5000. The GVWR for a MC-9 is 38,000 I believe.  My RTS currently weighs 32,000 and my toad weighs 4100.  And my RTS doesn't have the large cargo bays, extra large tanks, generator or large house battery bank.

I don't disagree with most of what you say. Also, I don't want anyone to misunderstand me here, I'm NOT trying to suggest the ISB is the end of all motor swaps, and that it'll work for everyone, every situation, no.

The ISB IMO is a niche market (of a niche); it's for people with lighter 40 footers and 35 footers, who wants a cheap engine swap with readily available parts, at low cost, and massive aftermarket support. The ISL/M/X can't fill any of those requirements.

As to concerns of the ISB's ability to gross mid 30,000 lbs, day in, day out, here's some proof:

(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi240.photobucket.com%2Falbums%2Fff184%2Fccoop769%2FIMG00022-20100712-1500.jpg&hash=b3bdad80c491e859fc080d9418568d705697a94a)

(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi240.photobucket.com%2Falbums%2Fff184%2Fccoop769%2FIMG00023-20100712-1538.jpg&hash=91dd66a16c47a6b8164a86ef0cfac197518c15de)

(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi240.photobucket.com%2Falbums%2Fff184%2Fccoop769%2F9589490645_ORIG.jpg&hash=7d3a68be483ecbda567b0d0adc0fe04fe295d57d)

(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi643.photobucket.com%2Falbums%2Fuu155%2Fkodiakconstruction%2F100_0617.jpg&hash=87f77e7ffbf665379ab257e08870274708044568)

(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi643.photobucket.com%2Falbums%2Fuu155%2Fkodiakconstruction%2F100_0626.jpg&hash=9bdc5964ecebd87cdc1cfd61ae64d605b981539a)

(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi240.photobucket.com%2Falbums%2Fff184%2Fccoop769%2FIMG00046-20090219-1433.jpg&hash=21831fbdf01858563b094a4daab0f9b2a4724baa)


The above are pictures of hot shot haulers, grossing 36,000 lbs, using their ISB / 68RE trucks day and night, all over the country. The red truck has 310,000 miles as of today (07 truck), origional motor, still going strong. The only thing he did was a transmission replacement around 260,000 miles.

To me, this is a tougher load (high wind resistance), and much tougher duty cycle, than MOST busnuts would ever face. Yes, I realize there're some folks out there driving a lot more than others, and in their case, an ISM would probably be a better solution.

Again, for myself, a 310,000 mile engine life is more than I can dream of, and probably more than an 8V71 can offer.

Quote from: arl on October 29, 2010, 10:22:57 PM
How do I connect with this Mike L. person that did the L10 job and is happy with it?

The guy you are looking for is Mike Lutestanski.  He's in the member list, under the M's.  I think he's home right now but he must not be following this thread.  If you can't get him by PM then PM me and I'll give you his phone number.  The other guy on here who did an L10 swap is Melbo.  He's in Albuquerque and he's also in the member list under the M's.  Same deal as Mike if you can't reach him by PM.

As has been noted, the L10 would do the job.  Only issue is that it has been out of production for many years.  It became the M11 (electronic) and then the ISM. 

Being old, I don't know what you will find in the way of a reasonably good engine.  It would have to have been rebuilt and you will need to get documentation on the rebuild. 

As I recall, the engine does not use an air to air charge air cooler.  That will make the swap easier.  You still have to deal with the gearing issue (if you do it correctly). I don't think you will find one with a Allison World behind it (has two ODs).  You might find one with a truck OD manual transmission. 

I really think you would be lucky to do it for $8K and only if you do all the work yourself.  In terms of getting it done in two months, I think that would be a stretch as well.  One of the biggest issues will be to find a good engine.  Since it is a mechanical engine, that will make the job easier.  But it is still a huge job. 

Jim

Your best bet with those time restraints is to get your original motor rebuilt by a real 2 stroke mechanic top to bottom and i think you would be happy, maybe not. Faster still would be a rebuilt long or short block from a reliabe engine reman shop with a guarantee. No way i can see a engine swap/repower to a different engine trans set up  in that time frame. And for less than $20k (more like 30K) with someone else doing the work. With you supervising please add another 10 grand, its in the mechanics rule book ;)

Quote from: arl on October 29, 2010, 10:22:57 PM
More great help.  Thanks folks.

I've been told that a rebuild in my 8V71 will cost 2-3K in parts.

We drive 30,000 miles a year, mostly east of the rockies, but could easily find ourselves coast to coast .  We go from south tip of texas to Canada twice a year.   Climate changes, terrain changes, altitude, plains, mountains, we see it all.  So I'm inclined to have a little extra when necessary, which the ISB may or may not provide. 

Alan, if you can do most of the work yourself, and get parts at that price, then it's probably your best bet.

The 8V71, like the 6V71 in my 35 footer, is probably decent in power at sea level. My biggest complaint is the dramatic drop in power at altitude. I'm one of those guys that hate to see smoke out of my exhaust, which limits me to less than 3/4 throttle above 4000 feet.

My recommendation is to do a rebuild, and design a low pressure turbo setup. Don Fairchild is the expert in this field of course, so you'll want to get some ideas from him as to how it should be done.

My own goal is only 3 - 5 psi, with stock injectors, stock pistons, and no aftercooling. In other words, I won't have significant power increase, but that power will be available anywhere on the planet! My only concern is whether I need turbo spec seals in the blower or not.

QuoteNo way i can see a engine swap/repower to a different engine trans set up  in that time frame. And for less than $20k (more like 30K) with someone else doing the work.

I had mine done with an L10 and it was less than 20 -- If you are going to avoid the diff change out you need to go with a trans that has the OD -- my diff is the stock 3.70 and my trans is the ZF and it only has a 1:1 in fourth.

I can cruise over 70 but I am running about 2200 rpm so I stay at about 63 which is about 2000 rpm -- I get about 7 mpg at the 2000 and closer to 6 when I think I need to get there quicker.

HTH

YMM "definitely" V

Melbo

Interesting thread!

Way back some place, Arl, you put your RPM at highway speeds as..hold on,gotta find it again...

reply #22 

"1.  Is the ISB a 2-stroke?  Why the high rpms?  3000?  That sounds high, even for me, who is used to 2300 rpm cruising speed at 64mph.  I thought THAT was high.  The poor 8v71 sounds like its hurting itself."

With all the "chatter", everyone missed it. 2300 rpm at 64 mph doesn't sound right at all.

An MC9 with 3.7 differential gear should turn 2100 rpm at 70 mph.

Tachometer maybe out of whack...or????

As for noise, how is that getting into the coach? The access holes down the back properly sealed up? Muffler blown out?

And on the oil consumption, what oil are you using?
My low mileage 8V71 burned oil badly when I got it from the previous owner, as a hired hand had put 15W40 in it. After I changed it to low ash CF2 40wt, consumption pretty much vanished.

I'm partial to keeping my money and energy outputs to a minimum when possible. There may be simple solutions short of a re-power. And your fuel economy is good, so how much can be wrong?

happy coaching!
buswarrior

The Cummins ISB is made in two sizes.  6.7 liters for automotive use and 5.9 liter for marine use.  Cummins has a 480hp @ 3400rpm version for inboard and inboard/outboard use in pleasure craft-course this is only a 15 minute rating.  Both engines are inline 6's, 4 stroke, common rail fuel injected (current engines).  Good Luck, TomC