MyE28.com

I have heard that the rods are forged from BMW and are good for around 700hp, is this true? How good are the cranks in these cars? Could they whistand decent hp (300ish) without any modification? Also what about the head, is it good or bad for boosting. I dont really want to buy a new head or change the size of the valves at all because I just got my JE pistons from TCD and I dont want any more vavle/piston interference because it seems it is pretty hardcore already due to the fact my piston is 8.1:1 and still has a dip in the piston for valve clearence. Any help would be awesome, thanks guys.

I don't personally know about the rods, but I know the crank will easily due 400bhp. The head is perfectly fine for moderate boosting. If you really want to go crazy you might want to look at sodium filled valves and ceramic coated exhaust ports. The reason you have a releaf in the piston is because the motor is an interferance fit motor, meaning if the valves and pistons are out of timing they will hit. You need the releaves to be able to ensure that even with a little valve float you won't hit the pistons.

Hope this helps

In addition,
The stock rods will handle what the stock crank will handle. Thats close enough for me.

300ish is easy with stock internals and stock head.

RussC

If you really want a heavy duty crank, get one of the forged ones out of the M90 motor... The 3.5's up to 5/1982. You can buy mine for one billion dollars.

jimbixjr wrote:I have heard that the rods are forged from BMW and are good for around 700hp, is this true? How good are the cranks in these cars? Could they whistand decent hp (300ish) without any modification? Also what about the head, is it good or bad for boosting. I dont really want to buy a new head or change the size of the valves at all because I just got my JE pistons from TCD and I dont want any more vavle/piston interference because it seems it is pretty hardcore already due to the fact my piston is 8.1:1 and still has a dip in the piston for valve clearence. Any help would be awesome, thanks guys.

The piston has a relief because it is decided to be used with the m30b35 cyl head which has the bigger intake valve and combustion chamber. Using it with a b34 cyl head will yield ~8.5 CR.

Todd

How much benefit would a b35 head yeild?

jimbixjr wrote:How much benefit would a b35 head yeild?

b35 head gains ~25-35hp over b34 head depending on tuning. Thats with the 1 point higher compression.

RussC

EuroShark wrote:If you really want a heavy duty crank, get one of the forged ones out of the M90 motor... The 3.5's up to 5/1982. You can buy mine for one billion dollars.

hmm, I have heard misinformation that all of the m30 ones were forged. Is it true that it is misinformation?

RDAvena wrote: hmm, I have heard misinformation that all of the m30 ones were forged. Is it true that it is misinformation?

I've heard the same thing... are we all wrong?

M20 and M30 cams are different, but I thought all BMW cranks were forged. Not saying I'm right, just what I've heard over the years.

I thought that the only way to get a forged crank for an M20 was to use a TD crank. And I think all M30 cranks are forged. My thoughts and reality do not always match.

most powerful m30 in the world that i know of is in sweden and make 710 hp at 6500 RPM on stock rods and crank.

I thought they were all forged. The ones in the later 3.5 were heat treated if im not mistanken.

Is there a book that BMW or anybody with correct information sells with all this type of information in it?

M30 cranks are forged -- you can tell by looking at them. I have the BMW blue service manuals for E3/E9 and they say forged crank.

Devinder

Where in the manual is that specific information? I'll check my e28 FSM later and tell everyone what it says.

Jeremy

It's in the specifications in front of the engine section.

It may not be in the later blue books. I know BMW removed a lot of good information over the years like the cam timing events.

Devinder wrote:It's in the specifications in front of the engine section.

It may not be in the later blue books. I know BMW removed a lot of good information over the years like the cam timing events.

Yea, it's not in there.

Jeremy

as far as I know all M30 cranks are forged

I have spotted a euro 82 m30 and also picked up a B35 head at pickm apart. Well will the 10.1 pistons from euro motor have enough clearence for the larger intake valves in the b35 head? And which cam to run 272 or 264?

Jimbeaux

DMNaskale wrote: ...My thoughts and reality do not always match.

Holla! 8)