MCI 8 Repower

[NickRussell]

Our worn our 8V71 with Allison 740 needs replaced if we are goign to keep our bus. We have had the rack run and all the standard upgrades done, but it's just very lacking in power, and it overheats terribly climbing the grades out west. It's okay back east, but we have lived and traveled in in 8 years and it has gotten worse over time.

Both Luke at US Coach and Sam Caylor agree that it's time to either rebuild or swap it out. I was talking to Sam today about a swap, and I'm comfortable with the price of an 8V92 turbo with new radiators, etc, with him doing the labor. My question is, what kind of difference in power will I see?

To give you some examples, climbing up Jellico Mountain on I-75 southbound in Tennessee, I was down to 15 miles per hour. On I-40 eastbound between Kingman AZ and Flagstaff last month I was down to 10 MPH. Last week on the long, gentle climb into Albuquerque eastbound, before youi drop down into the valley, we were at 15 MPH. The same going north on I-17 between Phoenix and Flagstaff. A couple of years ago, on I-90 on the Idaho-Montana border we were doing about 10 MPH.

Has anyone driven these routes in a bus with  an 8v92 turbo and Allison 740? What kinds of speeds could you maintian?

Yes, I know a four stroke is a better option, but given the money we have available, that's not an option. 

[buswarrior]

wow, that's a tired engine!

From Detroit to Florida S/B, I only recall dropping down into 2nd gear once on I75 briefly, up towards the top of the climb and being able to run high RPM with an 8V71/HT740 270 HP set-up in an MC8.

Depends on the power settings, but you will like just about any setting in an 8V92 compared to your present predicament.

Others chime in with your power settings...

happy coaching!
buswarrior

[poppi]

Could someone please explain to me why a 4 stroke is more than
a 6v92............ I've seen m11 with dyno reports for under 10k


   bye the bye I drove that same idaho/montana pass at 45mph in second, 3rd was to tall
for the slope with just one of those old L10s.

Thanks
Skip

[NickRussell]

Poppi,
Where do you find these engines for under $10K? I have not been able to locate one.

[poppi]

Try here to start.

http://www.valtruck.com/search.php?part=3000

In the pull down pick Cummins then in the next one pick M11 Celect
then hit the search button

   There are many choices and models check them out

Skip

[rv_safetyman]

Nick welcome to the MAK board.  I have followed you blog a bit and felt your pain as you described climbing the hills.

The 8V92 will be a great engine for you *IF* you size the radiators to cool the beast.  Be sure to use the latest fin technology and seal them very well.

The 8V92 can have up to 500 HP vs your 270-318 with comparable torque ratings.  It will have a turbo and that will make a huge difference at altitude.

Concerning the M11/ISM, the under 10K should be the norm in this market with a little searching.  Would be true with most four stroke engines.  However, the gearing with the four stroke is a huge issue and very costly to address (1400 cruise RPM for 4 stoke vs 2100 cruise with the two stroke).  

The cost of conversion with a four stroke is probably three times the two stroke.  This is especially true, since you would be converting from mechanical to electronic engine.

The M11/ISM is the ideal 4 stroke engine for your bus, but costly to do.  A great documentation was done by Brian Diehl:

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

Jim

[rip]

Nick; I have an 85 Prevost with a 8v92 and an Allison 748 .Living in AZ. I've run the Mt's many times.The worst is southbound from Camp Verde and the slowest is 35mph. I weight in at 40,000 lbs. and I pull a Toyota p/u.You should be happy with the re power to a 8v92.
   Don

[busnut104]

I did the swap that you are referring to, you will notice a great difference, and notice very little if any in millage, I bought some of my parts from Sam, from what I gather and my dealings with him he seams to be top notch and making this change before the bus co. 

[poppi]

    I don't know anything about anything so of coarse take anything I have to say as just a foolish almost old man.

  Tran. max length with a cummins M11 is around 27 1/2"

  from the same place you can get a allison HT747 for 2k and it might fit.    You can get bus pans and engine cradles for cummins. Hard to find but do remember MCI did have Cummins as an option engine. (so I have been told)
     at what series of MCI I do not know when they started.
  Then there are the ZF trannies (expensive to work on), new world and of course the auto standards.
granted going with the inlines limits your tranny options and Brian's is definately one
for the books.

    I have a stock diff on my bus.

FWIW
Skip

ps added tran length

[white-eagle]

Nick, we've got an eagle with 8v92t, 740 4 spd.  if i watch what i'm doing and keep the throttle down and the turbo boost at 15-18 then i can usually maintain 70 most of the time on i-75 in either direction.  Jellico, at worst, would be 3rd gear, 50 mph.  as i said, most of the time, if i can hit the bottom at 70 with the throttle down, it will run right up the hills.  however, if i let up or hit the hill at 60-65, then i might as well let up until it hits 55, then drop to 3rd and maintain at 50mph.

We also pull a heavy Chevy Express Van at about 7000#.  Our Eagle is about 39000.

[RJ]

Nick -

Long time no see!!  Arcadia 2004, right?  Anyway. . .

I'd have to agree with Sam & Luke on this one.  There's a world of difference between an 8V71N & an 8V92TA,  plus it's a comparatively easy swap.  Since the 8V92 was an optional engine in the 9s, and your engine compartment is virtually identical, you won't have as many fabrication issues that other re-powers entail.

Except the cooling issue.  You'll definitely need this addressed, and Sam's going to be a good source on this, since he specializes in MCIs, and probably has all you'll need out in his back 40.  Larger radiator cores, well sealed.  Larger squirrel cages and a smaller drive pulley are also part of that package, as well as larger openings into the engine compartment from the blower compartment.

Highly recommend additional oil cooling for the transmission, to avoid dumping the additional heat load into the engine cooling system.

Be aware, tho, that the 92 is NOT as forgiving as the 71 when it comes to getting hot.  As long as you drive it appropriately, you'll be fine.

FWIW & HTH. . .

[Zeroclearance]

Nick;

Have you thought about repowering with a Series 50 engine.   

Here is one >>  http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=180353709795QQssPageNameZMERC_VIC_RCRX_Pr2_PcY_BIN_IT&refitem=180345505046&itemcount=2&refwidgetloc=closed_view_item&usedrule1=CrossSell_LogicX&refwidgettype=cross_promot_widget&_trksid=p284.m183&_trkparms=algo%3DCRX%26its%3DS%252BI%26itu%3DUCI%252BSI%26otn%3D2

[NickRussell]

I would if I could find a good running motor and transmission, and a shop to do the work.

[TomC]

The nice thing about a 8V-92TA is that it is the same externally as the 8V-71 with the exception of the big vibration dampner (looks like a flywheel) on the front behind the pulley.  You'd have to move the engine/transmission back a couple of inches to maintain alignment with the blower pulleys, but that's about it.  Make sure you have the biggest radiators, and the fastest running blowers since the 8V-92TA is the hardest to cool truck/bus engine ever made (with the exception maybe of a 12V-71TA-but few around).  Good Luck, TomC

[poppi]

Incase you are on the east coast...........http://tpa.heavytruckparts.net/detailview.php?vehicle=3376&vendor=9119842&searchnum=2282824&searchnum=2282824

   it is a ddec II for what that is worth...... still 500 hp ain't shabby

Enjoy

Skip