Turbo on an 8v71

[DuaneMC7]

Hi all, I have searched the entire board and found nothing on what it takes to install a turbo on an 8v71. There must be someone out there that has gone through this. I am sure it involves more than the turbo itself perhaps piston, injector and timing changes. Any info on this would be greatly appreciated.

Thanks, Duane

[tucsontattoo]

  It takes a lotta work and a lotta money right off the top!
  First, new turbo pistons and liners ( In other words major overhaul).Then, new injectors.while your in there you have to change the injector timing. Plus all the turbo,intake plumbing,mounting brackets and new exhaust plumbing.  when your done you get to install a bigger radiator to boot.
  really want more power that bad find yourself a good used 6v92ta with all the stuff already on it and swap out.More horsepower,newer equipment. and maybe cheaper to do if you can find a good deal. 

                     Tucson

[Jerry Liebler]

Duane,
     This topic is a bit controversial.  I researched the topic by looking at what is different in turbo variants of the 8V71, from Detroit and I talked to a few very experienced DD rebuilders.  There are 2 styles of pistons, trunk and cross head, both have been used in turbo engines from Detroit.  All turbo engines use the 'large bearing' blower.  Many turbo engines have been rebuilt with the NA (high compression) pistons.  Turbo engines  are all standard timed.  Injector size determines horsepower,torque and cooling demand.  Injectors from N65 through N85+ are used in turbo engines. Generally the N70 is the largest used without the aftercooler (which requires a unique block).   If your engine is standard timed and has a large bearing blower it is 'turbo ready'.  If you stick to N65 injectors you won't gain horsepower, at sea level but will gain low speed torque and much less smoke with more power at higher alltitudes.  The biggest hassel in adding a turbo, I'm told', is finding all the 'plumbing'.  Going up to N70 injectors should give a bit more power but may show cooling problems.
Regards
Jerry 4107 1120

[phil4501]

  Many turbo engines have been rebuilt with the NA (high compression) pistons. 

When using the high compression pistons with a turbo, how much boost can you run?

[Jerry Liebler]

Phil,
    I can only 'indirectly' answer your question.  The shop that rebuilt my engine, Hillsboro Diesel in Hillsboro Oregon, has rebuilt hundreds of turbo engines with the NA cylinder kits.  Whatever boost the stock turbo provided has proven safe and reliable.  There are about a dozen different turbos that have been used on factory turboed engines, they all give different amounts of boost.  Diesel engines aren't like gas engines in that they do not have the 'detonation' issues that require lower compression with turbocharging.   When I add a turbo to mine, I'll simply pick a stock turbo from one of the lower horsepower setups.
Regards
Jerry 4107 1120

[coachcrazy]

stock turbos are usually low PSI (boost) 6-8 lbs,this is a pretty safe boost ratio.  When adding a turbo if you get a smaller one you will have quicker boost build up, because it needs less time for the pressure to build but a smaller turbo will limit the amount of boots you can use.  A big turbo will take longer to spool up but you can run much higher boost lvls and give your engine more power

[phil4501]

So, what size turbo at 6 to 8lbs. Would this only make a difference at elevation.

[TomC]

Phil- I am in the process of getting my bus ready to be turbo'ed by Don Fairchild in Bakersfield, Ca-mainly to cut smoke at altitude (not politically correct in this day and age, and for alittle more power-always seems that the bus slows down slowly on the hills).  First off, I have a transit with the 8V-71N with two piece pistons at the higher 18.7 to one compression ratio.  Since my bus came in both 96 and 102 wide, they kept the engine positioning the same, hence I have 13" between the radiator and outside grill-so enough room for an air to air intercooler.  The turbo engine was an option on the bus, so like most transits, they just installed the biggest radiator to facilitate all engines.  My radiator core is 40hx33 for a surface area of 1,320 sq in with five rows of copper/brass construction-more than enough for any engine.  I just ordered the custom made air to air intercooler yesterday from Sierra industries in Tulsa,Ok that will be under $700 with shipping.  What Don is going to do is to first pull the pistons out (I have 14,000mi on a recent overhaul) and just replace the rings with turbo rings to resist the extra pressure that would make excessive blowby.  Then, of course plumb up the entire mess.  Don will use a waste gated turbo for exact pressure control.  He is going to set the boost at 7-9psi, but the pressure taken from the air box (or inside the engine after the blower right before it goes in the cylinders). Considering that the blower puts out 2-4psi, you can see that the increase isn't going to be drastic.  And with the air to air intercooler, will eliminate the overheating of the air supply-and actually have a cooler intake air temp than if we used the TA block (this is also why vertually every on road truck has turbos with air to air intercooling).  Then, we will increase the injectors from the brown tag N65's to 7G70's that have a finer dispersion pattern than older designed N70's.  I figure the power will go from 318hp to about 350hp with the torque going from 800lb/ft to a bit over 1,000lb/ft.  Doesn't sound like much, but this will be the same up to 10,000ft elevation.  Last month when I took the trip to Arizona and went to Flagstaff at 7,000ft elevation, my fuel mileage for that leg was only 4.6.  Even so, averaged 5.8 for the trip.  So overall, I'm hoping for over 6mpg to be seen.  But once again, I'm doing this mainly for smoke control and to maintain horsepower at altitude, so maybe I can get up to the Eisenhower tunnel on I-70 in Colorado at 11,000ft elevation-which is the highest interstate pass in the U.S.  I'll keep you posted, but won't actually have the work done until October when the weather will be cooler in Bakersfield, and I can go on a couple of trips in the meantime.  I figure the project is going to be $4-5000.  Alot cheaper than a whole engine replacement.  Good Luck, TomC

[phil4501]

Tom, thanks for the info. What if Duane wanted, say, 380 horsepower and had enough radiator to do the job. Duane seems like the kind of guy that would prefer to see what is possible with the 8V71 before he thinks about 8V92. I, er, I mean Duane realizes that you are pretty sharp with this stuff and have thought things through to come up with your combination. But if you were in need of a few more ponies, what would be the combo. Also what turbo are you planning to use?

Phil Zisakis

[TomC]

Phil- I could go higher, but would involve changing out the blower to a big bearing blower.  Also, changing out the pistons to the lower compression would be better.  As long as you use an air to air intercooler, you can get away with staying with your present block.  Since the 4501 had fans on both sides and most people take out the A/C, the fan for the A/C condensor would be prime to turn into the air to air intercooler! 
Don Fairchild in Bakersfield Ca has his own company called Clean Cam Technology.  He has done much experimentation on the 8V-71 and can get 500hp out of one without much problem.  I'd suggest you give Don a call and discuss what you want to do.  Remember, it costs money to go fast-how fast do you want to go?  Don's phone number is- 661-391-4520.  Good Luck, TomC

[phil4501]

I believe I have the small bearing blower as well. 350 horse seems to be the wall where after that it starts to be high dollar. I think that this will be my target. The plan  is to swap the trans out for a road ranger and copy your 8v71setup. I would like to keep the original bus air though. Is my only option to find a ta block or can the intercooler be installed elsewhere or in conjuction with the bus air/engine radiator.

I am still in the planning stages, I don't like to waste a businessmans time until I have a better idea of what the standard setups would be,vocabulary, and budget. I appreciate the time you have taken shed some light on the subject.  My next step was to pay some attention to the injectors. It seemed appropriate to work out a total induction plan. I like yours.

My coach was good for about 10 mph in 1st going up the CA hills. It does much better now but need to take it out for another spin on the grades to see how much I gained from just the small issues I have fixed. It feels much better now, but we will see.

[TomC]

Phil- from riding in heavy buses in the past with the 8V-71N, we climbed the Bishop grade in 2nd doing in the 25mph range.  With the turbo, should add 10-15mph to that figure.  If you're going to do a complete overhaul, or your engine is tired, maybe switching to the TA block would be good.  I only have 14,000 miles on an overhaul, so I want to get some more miles out of the exsisting engine.  If you have the room you could mount the air to air on the outside of the radiator, like the trucks do.  If you still have your A/C, I wouldn't put it on the outside of the condensor since it might make for too high pressures in the system.  Good Luck,TomC

[phil4501]

My engine, if I had to guess, has about 80,000. I don't know this for a fact. Da book is on it's way. All the work done so far has been neglected maintenance. It seems as  everything I do yields remarkable results so far. I will keep my eyes open for a ta block. The figures you mentioned for the Bishop grade would be welcome indeed. I blew a front tire today so it looks as if I'll turn my attention to the tires and suspension for a while.

Duane, sorry if I hijacked your thread. You posted at just the right time.