Best sohc m20 head? - BMW Forum

wheelerdealer · 03-08-2006, 08:06 PM

I just bought my first bimmer project. It is a 1989 525i in mint condition besides the broken timing belt. ( ouch lol ) Well when it broke it some tabs off for on the head for the rocker arms so its junk. I was wondering if people put a head from a 3-series or something on these to make them run alot better?

Do people put dohc cam heads on these blocks?

what is a good website to check bmw head casting numbers?

thanks
alex

Torque · 03-08-2006, 08:14 PM

Head is the same on 525i, 325i/is ...

You can't put 'dohc cam' heads on the m20 block ... there was no DOHC m20, and m50 head will not work on a m20 block unless you are some kind of magician.

check out www.realoem.com/bmw/select.do that might help you with the casting numbers

ps. edit: it wont run any better with a head from a 325 .. its same

wheelerdealer · 03-08-2006, 08:25 PM

Is there any better year of head?

like bigger valves or better water passages?

sp0rky · 03-08-2006, 11:42 PM

e34s used the latest version of the m20. It's the highest performance from the factory for the m20.
The best thing for performance is the late model i head on an older m20 2.8 eta block. That makes for good torque.

Maybe consider getting a set of cams and stiffer valve springs if you want more performance...

good luck

da_bull · 03-09-2006, 05:16 AM

Quote:

Originally Posted by sp0rky

The best thing for performance is the late model i head on an older m20 2.8 eta block. That makes for good torque.

Ya hear that Torque, you getcha one of those and that'll make you good. I dunno how, but nonetheless.

Torque · 03-09-2006, 10:04 AM

Quote:

Originally Posted by da_bull

Ya hear that Torque, you getcha one of those and that'll make you good. I dunno how, but nonetheless.

I thought I already had a late model one. lol

07/90 build date ... either way I don't see how it would help anything.

wheelerdealer · 03-09-2006, 01:11 PM

Would a head off a 1987 525e be the same? There is one on ebay cheap.

da_bull · 03-09-2006, 08:25 PM

Quote:

Originally Posted by Torque

I thought I already had a late model one. lol

07/90 build date ... either way I don't see how it would help anything.

I meant you personally, theres no help for our cars, less an M5 drive-train / suspension swap

Torque · 03-09-2006, 09:13 PM

Quote:

Originally Posted by da_bull

I meant you personally, theres no help for our cars, less an M5 drive-train / suspension swap

ah, yes m20 head for myself. i need help installing it tho.

btw, theres a e34-only meet in chicago on a saturday in april (i believe -- website down at the moment so i cant check) ... u should go.

im honestly considering going up there.

da_bull · 03-10-2006, 05:22 AM

Chicagos like an 8 hour drive for me. Maybe a little further than I want to drive. My two trips this year are the Street Rod Nationals in Louisville (that trip is long enough), and the Good Guys show in Kansas City (only a couple hours), I want to try to finish my street rod this year. I dunno, maybe???

Sorry for the hijack...

sp0rky · 03-10-2006, 01:31 PM

a head from an e will decrease your performance. It has to be an i head.

The only e parts that enhance performance is the block. The e heads are restrictive, but the blocks are larger - so when mated with an i head, you effectively have a 2.8 liter m20 which can match output levels of a stock m50 b25