Debating...I head swap on e motor/full i swap

[phenryiv1]

lower compression, yes, and excellent for FI. not sure about interference between the valves. however, you don't get the matching head to head. I am running 87 325e with i head (and just about everything else).

Leo

What pistons? Stock eta? If you have stock eta pistons and a stock b25 885 head, then clearly you don't have interference.

[DetailAddict]

yep. and isn't that what u were talking about? ur 87 b27 with b25 885 head?

What pistons? Stock eta? If you have stock eta pistons and a stock b25 885 head, then clearly you don't have interference.

[strang3majik]

Detail addict. No offense but I have no idea what was said in your first post. Lol

And the stock era pistons lower compression being there is more cylinder volume above them at tdc. Therefore there should be more valve clearance.

And Chris That's what I'm thinking. I love low end torque and with the 2.7 I think I'll get a little more bottome end while still keeping the majority of the top end from the I motor. Should be a good balance. The lower compression sucks, but hey, I can buy regular even with a chip and most likely detonation shouldn't even be a potential problem. Lol.

And good for boost later on :)

If we're talking a 10hp difference between engines that's not really enough to feel and that can be easily made up with a cam, chip, etc. so, as long as compression check out on the 2.7 that's what I'm going to do. But the 50-60hp increase at the wheels over what I have now. That'll be noticeable.

I'm probably even going to keep the dual mass flywheel to help with some more low end inertia.

[e30jake]

OT but does anyone have dynos of the difference between the eta and seta bottom end with the I head?

[strang3majik]

OT but does anyone have dynos of the difference between the eta and seta bottom end with the I head?

Not off topic. I'd be interested to know as we'll what a point of compression does.

[ForcedFirebird]

I was told the eta manifold has better flow than the seta and I manifolds. I'm going to be doing a 2.7I non stroker on my seta here soon and boosting it. if your car is your dd just swap the whole engine because once you rip into the motors there is going to be some good down time

Um, we have flowed the eta, seta and i manifolds at our shop. the eta does not out flow the i, you need to re-read my thread ;)

stock m20b25 should make about 145 whp/ 148lb/ft

heres a thread about it.

http://forums.bimmerforums.com/forum/showthread.php?t=1471732

a head swap might make a tad bit lower but will have more tq at a lower rpm. Power falls off after 6200 rpms.

My car made 134/145 using stock components. After a head shave, thinner gasket and adjustable cam gear to make up for the crank to cam distance, it would walk an i car, even with the 2.93 final drive.

Not off topic. I'd be interested to know as we'll what a point of compression does.

eta with i head = 8.43:1
seta = 8.5:1
m20b25 = 8.8:1

http://www.scribd.com/doc/12801628/Mahle-Pistons-M20#fullscreen

[phenryiv1]

yep. and isn't that what u were talking about? ur 87 b27 with b25 885 head?

Yes, that is what I was asking. I just wanted to confirm that I correctly read what you were saying.

[Chriskbmx]

well. thats almost 8.5.1 compression sounds good to me. know all we have to do is find you a 288 cam and some 19lbs injectors and we will be good to go.

[strang3majik]

I'm not getting how less than half a point of compression makes that large a difference. Lol. But maybe these engines it does.

Anyhow, Chris I'm thinking that 323i cam.

What's the thinnest head gasket out there?

[ForcedFirebird]

I used a .050" Cometic gasket and shaved the head .015"

Make sure you check valve to piston clearance.

[Chriskbmx]

I used a .050" Cometic gasket and shaved the head .015"

Make sure you check valve to piston clearance.

how much did shaving the head and thinner headgasket do for the compression? also what was your valve to piston cleanance?

[ForcedFirebird]

I didn't cc anything before assembly. Valves were close though.

[Chriskbmx]

I didn't cc anything before assembly. Valves were close though.

but you didn't have any interferance issues? and what did the machining cost you on the head?

[strang3majik]

To get a head milled should be less than $100.

I got the 2.2 head for the Omni done at a machine shop in FL for $50. Just make sure they know what they're doing as to not shave too much off.

[Chriskbmx]

haha i was trying to find this information for your sake lol but im thinking about building my own stroker with my eta and seeing who can make the most power lol me or you.