Couple FI on an eta based 2.7L questions

[Kozworth]

Edit: Thought I found my answer, but I keep finding conflicting answers.

Build:87 eta block, 885 head, arp studs, mls gasket.

I keep reading that e pistons wont work with I head because of the shape, then Ive also read they work but lower the CR to ~7.9:1. Ive read that an eta block with i pistons and 885 head gets about 8.3:1 cr on two sources, but then this site says:

"using a 325i head on a later 10.2:1 Eta short engine will give a CR of 9.4:1 which is plenty. If you can even find an early 11:1 Eta engine, the CR would be 10:1 which is even better"
-84.45.115.78/e30zonewiki/index.php/Building_a_2.7

On top of that, Ive read that stock hg is .070 uncompressed, while ive acutally seen a pic of a micrometer on a stock hg read .08, and ive also seen people saying that the hg compressed is .08..

Strictly eta does not give a defined answer for the compression ratio, just stating its "low" and so does many google searches.

My question is, I am planning on an 87 eta block (would prefer not swapping pistons but do have access to I pistons) with an 885 head, a mls hg, and arp studs. I am wondering what my CR is with "x" headgasket, so I know which mls gasket to order. I want just a good boosting compression since I will be running a holset.

Sorry for the post, ive spent the last couple days, and hopefully this thread will clear up any compression issues with real facts. I tried calculating myself but couldnt even find steady data reguarding stock headgasket thickness compressed vs uncompressed.

Thanks

[Cyrix2k]

if you need help, give me a shout. My old setup was a boosted eta.

[325ix]

I can't remember the exact stock cr numbers but, I believe the i head eta is approximately and 8.8:1 compression ratio. This is perfect for boost. I would just go with a stock size head gasket. Also, unless you are planning major boost, arp headstuds with a stock HG is fine for most any boost number. There have been quite a few complaints about the MLS gaskets.

[Kozworth]

Howso for the complaints? It wqould be easier just doing lower gasket set for 80 then a mls for 220. I read that stock gasket size is eithor 0.08 or 0.07 can anyone can confirm this?

[325ix]

Howso for the complaints? It wqould be easier just doing lower gasket set for 80 then a mls for 220. I read that stock gasket size is eithor 0.08 or 0.07 can anyone can confirm this?

I believe they blow out due to poor quality. Let me see if I can dig something up.

[Ginsterman98]

Old ish thread, but what fails with these gaskets, MLS to be exact? If you get the head decked and copper spray it should be fine and it should be stronger than the OEM paper gasket.

[einstein57]

I can't remember the exact stock cr numbers but, I believe the i head eta is approximately and 8.8:1 compression ratio. This is perfect for boost. I would just go with a stock size head gasket. Also, unless you are planning major boost, arp headstuds with a stock HG is fine for most any boost number. There have been quite a few complaints about the MLS gaskets.

a standard m20 b25 is 8.8:1

[Rowleym]

Old ish thread, but what fails with these gaskets, MLS to be exact? If you get the head decked and copper spray it should be fine and it should be stronger than the OEM paper gasket.

Some people had problems with them not sealing properly. Personally, I think that its because they weren't installed properly or something like that. Nearly all the e36 guys use them, and with great results. They normally recommend a 50 RA or better finish I think

[Ginsterman98]

Ok cool, thanks for the tip. I always check the head for flatness but didn't know the surface finish could effect it. I use MLS on my VR6 with no issues, just copper spray it, lol.

[dashboardmonkey]

Why not o-ring the block?

[Ginsterman98]

Why not o-ring the block?

I'll look into it. Never had issue with MLS gaskets before though. Sorry for the thread jack OP.