black smoke up hills????

[Lonnie time to go]

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

[Dreamscape]

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

[Sammy]

Check your air filter and all hoses and clamps for the air intake system.

[NJT 5573]

I don't see how you could get a 8V71 to run without some black smoke.

[TomC]

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

[RJ]

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. . .

[pvcces]

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

[Busted Knuckle]

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!   BK 

[TomC]

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

[Airbag]

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?

[HB of CJ]

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. 

[Barn Owl]

My PO gave me N70 injectors. Try living with that! 

[Lonnie time to go]

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.

[Busted Knuckle]

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   BK 

[TomC]

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