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Author Topic: Bus Is Now Turboed!  (Read 2546 times)
TomC
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« on: December 19, 2006, 08:24:02 AM »

Drove up to Bakersfield (live in L.A.), picked up the bus that Don Fairchild had turboed for me.  Hooked up the car (3750lb Mercedes-Benz 300 turbo-Diesel) and went to Las Vegas.  Pulling Tahachepi, it was 10mph faster on the hill, and on the flat actually had some passing power!  Coming back from Las Vegas on I-15, pulling the big hill south of the Nev border, once again was 10mph faster (40 compared to 30) on the hill.  Plus, once clearing the hill, didn't down shift all the way home.  The slowest on any other hill was 50mph.

For those that don't know, I have an AMGeneral transit with a 8V-71N and Allison V730, 4.625 rears and 11R-24.5 rubber.  Didn't like that the engine smoked at altitude, so had the turbo installed. 

What Don did- first was to pull one of the heads and one of the pistons to see what piston rings I had (the engine has 13,000 miles on a full overhaul).  Luckily I had the transit type rings that seal better than the over the road truck type rings, mainly to control the bypassing of compression gases with the higher turbo boost.  Don pulled the back of the engine off to inspect the drive gears (all OK), pulled the oil pump since the oil pressure was a bit low and found the oil pump drive key about to shear off.  Installed new injectors (went from N65 to 9G75).  Also sent out the Allison to be rebuilt and found the 3rd and forward clutch about to go.  After all the engineering and new plumbing was installed to connect the air to air intercooler, Don took the engine in the cradle over to Delaney and Ahlf to run on their engine dyno.  Got the engine up to 650lb/ft of torque and blew out the blower seals.  If the blower had been rebuilt in the last 10 years, then automatically the blower would have the turbo seals.  Obviously, mine didn't.  So Don pulled the blower and he found that the block is basically a turbo block without the aftercooler because of the extra meat on the castings and that the big bearing blower mounts were in the block.  Don found some big blower end plates, put turbo seals in and added the bypass valve.  Except for the higher compression (18.7 compared to 17.0) my engine is now a turbo engine.  At full boost, it is putting out 13.5lbs of boost.  Don would like it to be 15lbs (most turbos are around 25lbs).  Also will be installing a fuel modulator that controls the throttle to keep down the black smoke.  Now if I push to fast on the throttle, it looks like a locomotive starting-which I don't want.  The whole reason for this project was to get rid of the smoke. 

I will be taking the bus back up to Don for some fine tuning in January.  In the meantime, I will pull the radiator and have the core increased from 5 row to 7 row since pulling Tahacepi in 72 degree weather put the engine temp up to 200 (I then backed off, but still pulled the hill at 35mph).

I am tickled to death at the increase in power and the fact that now you actually have to feather the throttle rather than just mashing it to the floor at every little hill.  If you have a 8V-71N without enough power, rather than go through the agony and expense of changing to another engine, I HIGHLY recommend you rebuild your present engine into a turbo that will get you up to 400hp and 1200 lb/ft torque (compared to 300hp and 800lb/ft).  8V-71's (any 71 for that matter-including those with 6-71's) are extremely tough, can take over speeding (2800rpm) and are very receptive to turboing.  92 series do not like to be taken over 2300rpm, have wet cylinder liners that can leak coolant into the oil, and are just more fragile of engines (I know I had one in my first truck).  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #1 on: December 19, 2006, 09:22:56 AM »

Thats great Tom,

I'll bet it feels like a new bus...

Good Luck with it.

Nick-
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« Reply #2 on: December 19, 2006, 09:56:39 AM »

Great idea, Tom, I will remember that for the future...

Jimmy
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« Reply #3 on: December 19, 2006, 03:57:36 PM »

Tomc
 what is your guess on the cost to rebuild a 8V71  to turbo specs instead of the regular rebuild costs.  How much of a cost differance
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« Reply #4 on: December 19, 2006, 05:25:06 PM »

Paso One- the actual rebuild should cost pretty much the same.  Have to add the turbo ($1500) and the intercooler ($1200 w/hardware). Then there is some plumbing, so total at time of overhaul I'd say about $4,000 more.  It is worth it!  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #5 on: December 19, 2006, 05:51:14 PM »

Tom,congratuations,so as right now what are you putting out for horsepower/torque.You indicated that your putting out roughly 13.5 pounds of boost,how much more of a kick in the but would you have if you were putting out normal 25 pounds of boost?Huh How long did it take for Don Fairchild to do the job......Frank
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« Reply #6 on: December 19, 2006, 07:27:39 PM »

Very cool, Tom. Last I heard you were staying with the high compression pistons and mild boost. ( I have been away). Is that the setup you ended up going with? Would you do it again the same way? It sounds as if you are very pleased with the results. Throw us some details when you get a chance...

Phil Zisakis
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« Reply #7 on: December 19, 2006, 08:06:20 PM »

Tom,

Tell me about Don Fairchild. Does he have his own shop or what is the name of his company?

I'll be in Bakersfield in the spring and would like to find out the cost to turbo my 671/4104 and maybe add an AT. Sounds as if he is a great guy to deal with.

If I read yiur post right it appears you spent around $4000 for your o/h? What was the additional turbo and IC cost?
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« Reply #8 on: December 19, 2006, 10:25:25 PM »

Frank- I could probably get 400-430hp with 25psi boost, but didn't want to have to change the pistons.  When it was dynoed, it was putting out 300hp at 1700rpm which computes out to 370hp at 2100rpm (which is correct for 75 injectors).  I gave Don alot of latitude as to time to do the conversion.  Don had other jobs in between.  If he had just done mine, it would have taken about 4 weeks.

Phil-  stayed with high compression pistons (18.7 to one) and a moderate boost.  What was changed was injectors from N65 to 9G75, blower changed from small bearing to large bearing with bypass valve, I installed the custom air to air intercooler, Don installed the turbo (which is a waste gated turbo from an early 12.7 liter Series 60), and modified intake and exhaust to accomodate the turbo.  I will have to increase the radiator capacity-have a 5 row now, and will go to a 7 row.

GUSC- Don Fairchild has an extensive background in Detroit 2 strokers with the 71 series being his favorite.  He knows all the neuances that are very tricky to get a 2 stroker to perform correctly.  He was wanting to do a 6-71 in the same manner as my 8V-71.  So I bet he'd be very interested in your 4104 project.  I estimated that it would cost about $4,000 more to add the turbo and air to air intercooler at the time of a normal engine overhaul.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #9 on: December 20, 2006, 04:02:29 AM »

Tom,

Your project is most interesting. I am glad you are satisfied. I will keep reading your posts on this subject. I don't know the overall condition and age of our DD 8v71. Have thought that rebuilding her sometime might be the best way to go. With the work you have done on yours, would work for me. I will have to find a DD guy in Abilene to help me. I hope I can find one as knowledgeable as your guy.

Good Luck and Happy Trails,

Paul

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« Reply #10 on: December 20, 2006, 07:09:32 AM »

Sounds great.

I am putting a turbo on my 4-71 this winter. I just got the blower back from the DD dealer with new seals and gasket kit. (CND $ 1200). I have the turbo (AireResearch for that motor, $1000). I have to build a adaptor to mount the turbo onto the exhaust manifold, and a bracket to support the weight, and some plumbing for intake and exhast. I have still to find out wether the existing oil bath air filter will do or not. It appears that the turbo set up will draw 700 to 1000 CFM. Does any of you know where I could find a suitable dry filter? Let me know please.

 I am keeping the same N 65 injectors and same pistons.

I'll let everybody know how it goes.

JC
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JC
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« Reply #11 on: December 21, 2006, 09:25:44 PM »

Tom,

How do I get in touch with Don?
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TomC
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« Reply #12 on: December 22, 2006, 07:57:16 AM »

Email me at work and I'll give you Don Fairchilds phone number since that would be considered to be advertising on the board.  I'll be in the office today.

Tchristman@LAFreightliner.com  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #13 on: December 22, 2006, 03:08:32 PM »

Tom,

thanks, I'll have to wait until I get home after the first of the year, I don't want to use my daughter's email system.
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« Reply #14 on: January 10, 2007, 01:37:28 PM »

Tom......Any idea as to how fast you would of pulled Tahachepi if your engine would of had the full 25lbs of boost(with proper cooling)

If a person was wanting to turbo his engine,do you think it would be cheaper to just buy a turbo engine and go thru it, rather then to go thru with all of the changes to the non turbo engine.

I've heard from one person that Don Fairchild is capable of taking the 8V71 up to
500 horsepower,has Don Fairchild ever spoken to you about this.

Did you upgrade your radiator yet,and if so,how much cooler do you run now..............Frank
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