2.7i people please comment

[SEdgell]

I'm planning to do the swap on my 86 es. I pulled the i head today, don't know when I'll be doing the swap, hopefully sometime this spring/summer...anyway, I was just trying to figure out who on here has done this swap and retained the stock US spec eta bottom end. What can I expect...what's your driving impression, what all should I look out for when doing the swap. Any info would be great...thanks in advance.

[Adrian_Visser]

dude 16 posts down from your post there is a post that says "this is what an eta bottom end and i head gets you"

did you think to maybe read it?

[SEdgell]

Yeah, I've been thru it before, but that guy is in Canada, and i'm not sure which compression ratio their ETA engines had. I've sent him a message asking that, but he's has never responded. I've searched and can't seem to find too much good info, never any straight answers.

[dashboardmonkey]

ETA motor is 11 to 1 iirc

Putting an I head makes it 8 to 1 iirc

compression ratios

[Jordan325iC]

ETA motor is 11 to 1 iirc

Putting an I head makes it 8 to 1 iirc

compression ratios

No. Not in the US.


For the US market:

Stock M20B25 325i compression: 8.8:1
Stock M20B27 325e compression: 9.0:1
Stock M20B27 1988 325e (Super ETA) compression: 8.5:1
Source

Hybrid numbers:
Hybrid 325i Head / 325e bottom end compression: 8.3:1 - I will take TChao's word for this one
Hybrid 325i Head / Super ETA bottom end compression: 8.5:1
Hybrid 325e Head / 325i bottom end compression: Impossible. Pistons smash valves

The "i" head swap on a normal eta gives you the same HP and slightly more torque than a regular 325i. Good upgrade for ETA guys, not worth it for m20b25 guys (unless you're turbocharging). People say the compression ratio is lower than optimal on the ETA block/i head combo, but people who have done it have no complaints.


Also, not sure if you know this or not, but you need more than just the head. You'll need the intake manifold + some m20b25 accessories to make the car run.

[SEdgell]

That's what I was thinking that the CR would be around, and everyone I've talked to have been happy with it. I was just hoping to hear from as many people who have done it as possible.