Turbo 535i/b34 drivetrain limits

Discussion pertaining to positive pressure E28s.
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Beemernut
Posts: 173
Joined: Jun 22, 2017 10:36 PM
Location: Harrisonburg, VA

Turbo 535i/b34 drivetrain limits

Post by Beemernut »

I have big plans for the Shark, probably later this year. Per Good'n'Tight style I'll probably use a Holset HX40 and aim for 400whp on pump gas and if I still need more, switch to e85. I've researched turbo M30's for probably the last year and a half off and on, and at this point I don't know how to sort out everything I've heard/read.

My questions are as follows. I'm assuming the stock motor can hold about 600wtq with a really good tune and studs/mls headgasket.

Do I need to upgrade my rockers if I'm keeping the stock rev limit?
How much torque will the stock clutch hold?
How much torque will the stock gearbox hold?
How much torque will the stock diff hold? Can I rebuild it if I blow it up? I think I have a 2.93 LSD, RPM @ 60mph are at 2200 IIRC.
How much torque will the stock drive axles hold? How can I make them stronger?

Is there any further reinforcement elsewhere that I need to do to eventually hold 600wtq?
I know most old BMWs sacrifice launching abilities to keep IRS for handling, what can I do for traction and eliminate wheelhop in the rear without doing something stupid like a Ford 9" rear conversion?

I know a lot of you guys have nothing to prove, but I want to prove to myself that a) I can build something crazy, by myself and b) I can eventually leave my American flag waving, Chevy drivin', gun totin' coworkers that talk crap about my cars, speechless. Yes, I'm immature. And I don't care at this point. :rofl:
Shadow
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Joined: Dec 28, 2008 10:03 PM
Location: USA

Re: Turbo 535i/b34 drivetrain limits

Post by Shadow »

i don't think anyone has a proven scientific answer for most of those questions
because some people blow their shit at 400hp, 500hp, whatever.

But from many years of beating the shit out of my m30s these are my opinions.

stock clutch like 5psi.
i had a freak stock clutch that started to slip a 8psi so really stock clutch is weak
you'll want to slam in a good clutch from the start especially with a shark. mine was in a tin can e30.

Rockers. Stock treated me good. just keep them adjusted and they won't break. use fuel cut only.
i've used crazy bang bang rev cuts and 7k redlines never broke one just keep them gudntite.

gearbox. never seen ppl break them but then people don't do 7k launches on mega drag slicks. so, idk.
i declear it bullet proof. Diff. Same thing. Non-LSD diffs break EZ without trying don't ever use them.
Axles... same. Real drag style ultra grip is what breaks the drivetrain. Wheel hop.

on e30s you raise the subframe to gain camber and use adjustment bolts. it helps tons.
the diff mount usually rips the fuck out too. idk about sharks. probably 3000 x more stout for sure.

600hp i would recommend opening up the ring gap. i've cracked all of my pistons from having stock gap .019 it was.
Nebraska_e28
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Re: Turbo 535i/b34 drivetrain limits

Post by Nebraska_e28 »

Build the car to your liking, then upgrade as needed.
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