I have read other posts on this subject, but i wonder.
Is the best way to fix this;
adding more air flow to engine by way of a duct from roof??
my bus is 4905 8V71 with some kind of blower
The best thing to do is, from my experience only, to either shift down or lighten up on the throttle. Black smoke usually means more unburnt fuel going out the tailpipe.
Example. When you apply full throttle in say third or fourth, look in your side mirrors. If you see black smoke let up on the throttle and see what happens, it should clear up. You need to keep the rpms up when going up a hill, don't lug the beast.
Paul
Check your air filter and all hoses and clamps for the air intake system.
I don't see how you could get a 8V71 to run without some black smoke.
I was in Ketchican, Alaska last year and the tour buses were rebuilt GMC fishbowls with 8V-71's and VS2-8's. They probably only had 55 injectors, but didn't smoke at all ever. When I put N65 brown tag injectors in my bus, it would lightly smoke at sea level when floored. All you had to do was raise up your foot by about an inch and the smoking would stop. At high altitudes, that was a different story-so much so, is why I turbocharged and air to air intercooled my bus. Now at high altitudes, only get a bit of smoke at take off, and none once the turbo is up.
Black smoke can be caused by not enough air (dirty air cleaner), too large injectors, or worn out injector tips. Good Luck, TomC
Time -
Perhaps this might help answer a few questions for you:
http://www.busnut.com/bbs/messages/12262/16204.html?1167073154.
In a nutshell:
Black smoke when climbing hills is unburned fuel, and, if not corrected, can lead to overheating. Black smoke while running on the flats is indicative of a dirty air filter 90% of the time.
To correct:
Make sure air filter is clean.
When pulling hills and you see black smoke, back out of the throttle slightly. If the smoke clears and the bus maintains it's speed, you had your foot in it too far. If the smoke clears and the bus starts losing speed, it's time to downshift to keep the revs in the 1700-1900 range on a partial throttle that Detroit two-strokes like best.
If you don't have a tach, they're a good investment, and the electrical ones are easy to hook up. Otherwise, mark the speedo (if it works) or make a note on the dash if you're using a GPS, for the maximum road speed in each gear. That way you'll always know which gear is appropriate for the current road speed.
FWIW & HTH. . .
;)
Time, two stroke engines have no way of creating a vacuum when the piston gomes down in the bore. This means that they have to be fed pressurized air to clear the cylinder and get ready for the next power stroke.
This is the purpose of the Rootes blower.
For what it's worth.
Tom Caffrey
Quote from: NJT 5573
I don't see how you could get a 8V71 to run without some black smoke.
Pay a visit to Don Fairchild and his company in Bakersfield, CA I'm sure Don would be happy to show you how he and his company do it! After all that is what they specialize in! If I were closer to Don, I'd be his worst nightmare and biggest non-paying pain in the butt regular! LOL! But until then I'll let Dale have that honor! LOL! ;D BK ;D
Don Fairchild did my turbocharging and air to air intercooling (first he's seen) on my bus. We used an early Series 60 turbo with waste gate to keep the turbo boost around 15psi, since I kept the high compression pistons. With 9G75 injectors, my power went from 300hp and 800lb/ft torque to 375hp and 1125lb/ft torque-a big difference in performance, with about .5 mpg better. Good Luck, TomC
Quote from: TomC on June 24, 2008, 08:17:25 AM
Don Fairchild did my turbocharging and air to air intercooling (first he's seen) on my bus. We used an early Series 60 turbo with waste gate to keep the turbo boost around 15psi, since I kept the high compression pistons. With 9G75 injectors, my power went from 300hp and 800lb/ft torque to 375hp and 1125lb/ft torque-a big difference in performance, with about .5 mpg better. Good Luck, TomC
What engine do you have? Does he have a kit for 8V71?
We also do not know how you are driving and shifting your coach. The best rule is to run the mill in each gear all the way up to the governor, then when the engine flattens out, upshift.
An example would be, if you are running at lets say 40 mph, most likely you would want to be in 3rd gear rather than 4th, if you have a 4 speed manual. Sounds strange, but true.
Another example of "speed in gears" would be 15 in first, 30 in 2nd, 50 in 3rd and whatever in 4th. You particular gear sets may differ, I just picked numbers pulled from memory.
Automobiles with manual trannys have a power to weight ratio that lets us run along in top gear down to a very low road speed, sometimes as little as 25 to 30 mph. Not in a Bus Conversion.
And....again, like already mentioned, it may just be a clogged air cleaner. Black smoke indicates unburned fuel. You can learn to "read" your exhaust and simply lift your foot. :) :) :)
My PO gave me N70 injectors. Try living with that! :'( :'( :'(
thank you tom and others
does don have a way to make a 8V71 into a turbo on this kind of bus. What would it cost I start saving for a future investment ????
By the way did I mention I don't know nothing about diesel engines.
what do you mean by running the gears. I was taught to high of rpm will blow a motor.
Sorry all I know is from reading all the old posts. I will also check the air filter thanks.
Quote from: timetogo40 on June 24, 2008, 03:41:39 PM
thank you tom and others
does don have a way to make a 8V71 into a turbo on this kind of bus. What would it cost I start saving for a future investment ????
By the way did I mention I don't know nothing about diesel engines.
what do you mean by running the gears. I was taught to high of rpm will blow a motor.
Sorry all I know is from reading all the old posts. I will also check the air filter thanks.
Yeah, but you weren't taught in a Detroit! (also lovingly remembered by those of us who have been breathing diesel fumes long enough to self creamate ourselves as
"SCREAM'N JIMMY'S"!)
Ask any old time trucker and they'll tell ya "slam ya hand in the door then drive it like ya stole it!" LOL! These engines here are designed to be run at or near max RPM for best performance! FWIW ;D BK ;D
I have my governor set at 2400rpm no load-many old truckers in the 60's and 70's used to turn the 8V-71's up to 2,800rpm with no problems. But- I would go no more than 2,500rpm just to make sure.
Your 4905 is much the same setup as my transit with the 8V-71 and V730 Allison automatic, with the exception of my bus being a 102" wide, so I had plenty of room for the air to air intercooler in front of the radiator. You could mount the air to air intercooler where the right transmission door is with an electric fan blowing out from the engine compartment-you won't suck air in since there is alot of pressure being created by the big engine radiator fan, so blowing out will be acceptable. My auxiliary transmission cooler is the same way, and it makes a difference.
Don Fairchild can build up a 8V-71 turbocharged and air to air intercooled engine using his pistons, liners, and camshafts to update your engine to at least 2002 smog standards. Using 80 injectors (which Detroit did on their last 8V-71TA) you can get 400hp with 1200lb/ft torque. Call Don @ 660-391-4520. Good Luck, TomC
Time, all diesels are governed; they would run away if they weren't. If the governor is functioning, you can't hurt them by flooring the accelerator while sitting still. This is called high idle speed on bulldozers, for example.
On the other hand, many of these engines are equipped with a fast idle which is not the same thing. Fast idle is used to maintain something around double normal idle speed to maintain air conditioning in a coach while at a short or meal stop.
High RPM can and will use more fuel, so keeping them at governed speed does not do much for fuel economy. The more efficient engines of today are normally running under 1500 RPM.
For what it's worth.
Tom Caffrey
Quote from: timetogo40 on June 24, 2008, 03:41:39 PM
By the way did I mention I don't know nothing about diesel engines.
what do you mean by running the gears. I was taught to high of rpm will blow a motor.
Time -Keep asking questions, and you'll learn all about diesels both here and on various other message boards.
Diesels are not like gas engines - they generate most of their power between idle and around 2100 rpm, which is usually where the governor is set.
Your average gas auto engine will happily rev to 6000 or more, depending on the make/model.
The stock 8V71 in your coach was normally set up for revenue service with N60 injectors and governed at 2100/2150. This combination gives about 275 hp and around 775 ft/lbs of torque, but also returns decent (for a bus) fuel economy. Something to consider at $5/gallon.
You can run a Detroit two-stroke like your 8V71 all day long on the governor at 2100 rpm and it won't hurt it at all, other than burn a lot of fuel.
"Running the gears" means exactly what HBofCJ said - you take the engine all the way to the governor in each gear before you shift up to the next one. It won't hurt this engine at all - as a matter of fact, you'll find, as a newbie, that the whole coach will seem to perform better if you do.
It's also important with the powertrain you've got, which is typical of most stick-shift highway coaches. With only four speeds in the manual gearbox, you need to use the full rpm range of the engine for best performance. If you have the automatic in your Buffalo, it's even more important that you shift it manually for best performance, especially when it comes to downshifting. Re-read that link I posted earlier regarding this. If nothing else, when running around town with a V-730 automatic, leave it in 2nd. When you hit the freeway, then shift to 3rd/D. BTDT, well worth the effort.
FWIW & HTH. . .
;)
Hey guys,
Much of the advice for shifting here is missing an important point - Time to Go's bus has an automatic tranny. Or maybe I'm missing the point and that you can do all of the discussed manual shifting with an automatic? I've only driven 4 Speeds.
Glenn
"Running the gears" is easy. What it means is that in a Bus Conversion with a 4 or 5 speed MANUAL tranny, and with the older 2-stroke Detroit Diesel engine, you rev up your mighty Detroit until it 1)...sounds like it is going to explode!, 2) If you have a tack, to anywhere from 2000 to 2300-2400 rpm, or, 3) if you are shifting by the speedometer (most common) you have a memorized speed range for each forward gear. Very easy actually. Like driving the older VW bugs.
An example. A lot of the older 35 foot MCI coaches had only 4 speed trannys. The gear ratios worked out to a corresponding mph speed range. 1st gear was good up to around 15 mph. 2nd gear from around 10mph up to 30mph. 3rd was good from about 25mph up to around 50mph and 4th gear was good from around 50 mph all the way up to the top speed of the bus. Normally you DID NOT stay in high gear at a low road speed pulling power from the mill.
Once you get used to it, it comes naturally. Obviously there are exceptions to the rule, like "drifting" down a very slight down grade at a moderate speed, you could (I know I got lazy and did soss.) leave it in high gear and just let the coach coast. The other way also is done, like climbing a steep long grade where the engine is really working. Instead of keeping your foot on the floor, you "backed out of it" slightly and kept high rpm, but with partial throttle. Detroits love this. They hate "lugging" Good luck. :) :) :)
Quote from: Tenor on June 25, 2008, 05:07:52 AM
Hey guys,
Much of the advice for shifting here is missing an important point - Time to Go's bus has an automatic tranny. Or maybe I'm missing the point and that you can do all of the discussed manual shifting with an automatic? I've only driven 4 Speeds.
Glenn
Glenn -For most busnuts that frequent this and the other message boards, because of the vintage of our vehicles, a lot of the info related to shifting a manual gearbox does, in some respects, apply to the most common automatic found in them, the HT-740. (The V-730 is basically the same gearbox with one less gear in it.)
If you want to maximize the performance, you shift it manually. If you don't really care, just put it in "D" and go. Which is really fine for 99.9% of most busnut's driving situations.
BUT -It's still important that you know the maximum road speed in each of the lower gears, because:
1. When climbing hills, you need to downshift it manually, otherwise it will shift too late on it's own, and then you're ready for another downshift, which it will again do too late. Good way to overheat the beast, btw, especially MCIs. The BNO article talks about how to do this smoothly.
2. When descending hills, knowing that the HT-740 will still upshift to protect itself when you exceed the maximum road speed in a lower gear, well, it could not only save you an expensive engine rebuild from over-revving, but it also could prevent a runaway bus because you're now going too fast for the hill (non-Jake brake equipped vehicles here).
So, yes, some of the manual shifting advice is valid for automatics, too.
FWIW & HTH. . .
;)
RJ,
Thank You! Thats the explanation that newbies need! So in comparison to hot rod car auto tranny's, most of the automatics in busses have a manual valve body that allows you to manually shift or just leave it in drive.
Glenn