turbocharging an "e" motor...

Sat Dec 23, 2006 10:39 pm

Anybody got experience in turbo'n a e30 325e?

Sat Dec 23, 2006 11:56 pm

It's just an engine at the end of the day so look at the compression ratio, think about manifolding, intercooling and engine management, decide upon how much power you want and where you want it, size the turbo accordingly and off you go!

Sun Dec 24, 2006 12:07 am

what is the c/r on the "e" m20 engines? thats mainly what i need to know

Sun Dec 24, 2006 12:11 am

early ones 9.6.1
late ones 8.8.1

Sun Dec 24, 2006 12:26 am

years?

im hoping the 528e im getting has a late m20 but if its an early one i am just gonna have to watch out for more knock...no biggie

Sun Dec 24, 2006 12:30 am

not sure of the change over if im honest but it might of been 88

Sun Dec 24, 2006 12:42 am

i think it is 88...hmm...doesnt really matter.

Anybody know how high i can rev an "e" head without damage? or do you think it wouldnt be worth it to run past redline with a big turbo?

Sun Dec 24, 2006 8:39 am

SMS19 wrote:what is the c/r on the "e" m20 engines? thats mainly what i need to know

8.5:1; 9.0:1; 10.2:1; 11:1

Sun Dec 24, 2006 1:32 pm

Compression ratio for a Federal 325e and 528e is 9:1. The very first thing you have to do is find out what head you have. Late cars (the 'Super Eta') have the 325i cylinder head with the casting number 1 705 885. You will need to look with a torch at the inlet manifold side of the head for this number - look to the left of the throttle body and you'll see the number or at last part of it.

If you have this head, you're in luck for tuning because it's got nice big ports and the biggest factory M20 valves. You will need to pull the head off and rebuild it with a 325i camshaft and valve springs. The original Eta had a cam with only four bearings rather than the seven of a standard M20 and the three non used cam bearings in the head were not drilled for an oil way. Some Super Etas had a four bearing cam, some had a seven bearing cam but all had the Eta valve timing. If your head only has a four bearing cam it's easy enough to drill the extra three oilways. Virtually all Super Etas (also available in Europe) have seven bearings and the change to the 885 head happned in September 1987.
So add a 325i cam and valve springs, a 325i inlet manifold with injectors and throttle body, air flow meter and early (metal bumper) ECU. You'll then have a nice 2.7 litre engine that revs to 6000 and has quite a bit more torque than a 325i.

The gearbox (you've got a 5 speed manual, right??) is the same 260 Getrag as a 325i. The Automatic is a weird Eta only unit that was a hybrid of a 3.5 litre gearbox with an M20 bellhousing. The final drive is a pretty tall - 2.79:1 on a manual and 2.93 on an auto. great for economy, not great for acceleration. A 325i diff will swap straight over.

For a turbo, the factory 9:1 compression is okayish. If you have a 200 head you can bolt a 325i head straight on which will lower the compression to 8.6:1 which is better. The 325i cam will be much better and a turbo unit with @250 bhp will pull that final drive a lot better!

Sun Dec 24, 2006 10:16 pm

hmm might have to start dumping all my money into the bmw.

Sun Dec 24, 2006 11:18 pm

How do you think it would do if i left the "e" head internals in it and just turbocharged that, a smaller turbo (internal wastegate)...megasquirt and the other supporting mods and just rev to like 5-5500?

Mon Dec 25, 2006 5:26 am

I would highly recommend you check out www.e30tech.com there are tons of threds about this right now and us yanks have more experiance with the US etas.
BTW the i head on a stock non super eta is just a bad combo. the pistons don't match the head and it is just wrong. it is however an easy way to get low CR for forced induction.

Mon Dec 25, 2006 8:07 am

yeah...im thinking about doing an m30 swap and then turbocharging that in the future...just gotta find an m30 to use.

Can somebody give me a list of all the parts i need for the swap?

Mon Dec 25, 2006 10:52 am

SMS19 wrote: Can somebody give me a list of all the parts i need for the swap?

All in the archives and current threads of this forum!

Mon Dec 25, 2006 10:54 am

Thanks bro

Mon Dec 25, 2006 12:28 pm

Im thinking about just getting an m20 engine from a 325i and swapping that in....wiring and everything should be the same right?

Mon Dec 25, 2006 1:09 pm

Straight swap, but IIRC, your existing diff ratio won't be suitable.

Mon Dec 25, 2006 1:10 pm

sorry but what does IIRC mean?

Also what diff should i use and from what car can i get it?

Mon Dec 25, 2006 1:17 pm

IIRC = If I recall correctly, and diff would be best obtained from the same car as the engine. Something in the 3.6 - 3.8 range would be about right.

Mon Dec 25, 2006 5:52 pm

Aight...im sure i can find a 325i at a junkyard around here somewhere...or just buy one thru the eurodepot

Mon Dec 25, 2006 6:12 pm

Im probably gonna buy a 325i engine and build the whole thing while its on a stand....and a turbo-system. This will probably take a good 1 or 2 to complete the whole car but it will be so worth it.

Im thinking...solid bottom end, 666 turbo adapter, t3/t4 turbo setup, megasquirt, 666 intake manifold, big FMIC, 3" exhaust, 3" chargepipes....the works.

Tue Dec 26, 2006 3:38 am

okay you must swap the i harness and ecu plus motor rear end, and rad. the wiring is totaly different. You should really check out the fourm i told you about.
Kind of funny i find american guys here asking questions the americans will know and send them to e30tech, and find euro guys on e30tech and send them here.

anyhow there are at least 5 guys running the set up you just listed on e30tech they should be able to walk you through the whole thing. Best of luck