Had anyone CC the M44 heads???

[MYBIMERZ3]

I wanted to lower the compression a bit in my Turbo Z3 by replacing the head gasket with a thicker custom MLS one, so I can run a bit more boost. Can anyone share this info with me??

Thanks,
JG

[silverm3bmw]

Not sure, how low you need to go? Just get the thickest gasket out there, lol. :D

[MYBIMERZ3]

silverm3bmw Thanks for your effortless advice... But I believe the M44 engines come with a static compression ratio of 10:1 or something close to it. I wanted to get very precise measurements, 'cause I wanted to get a static compression of 9.5:1

http://www.rbracing-rsr.com/compstaticcalc.html (http://www.rbracing-rsr.com/compstaticcalc.html)

http://www.rbracing-rsr.com/comprAdvHD.htm (http://www.rbracing-rsr.com/comprAdvHD.htm)

JG

[silverm3bmw]

Sure, no problem, or, you can just use the other advice posted. Oh, wait...........there is none.

You have it all there. Take the known compression, thickness of the compressed stock gasket, circumferance of O ring in gasket, diff in thickness of new gasket to old, add/ubtract/divide n multiply, that will tell you how many CC's to apply/add. Now you have solid advice, up to you to do the math.

Just looked at the link, http://www.rbracing-rsr.com/compstaticcalc.html , its all there for you, what are we missing?

[MYBIMERZ3]

I need to know the "Deck Height", I dont have this... =/

[silverm3bmw]

Not sure if that even matters. If you have a stock head gasket on the car, its a moot point I would think, since your going thicker on the gasket. You should still have the info you need. Just pick a deck height and stick with it between the two scenarios.

Well, if I can ever find my tools I can check it on my block. I was concerned about that myself. I need to mill my deck and was looking at it. While I am not a micrometer, it looked like a 0 deck height.

[MYBIMERZ3]

Thank you silverm3bmw. Yes this is indeed needed in either scenario. Humn.. I wonder if anyone has already taken these measurements...

[Toby B]

...yeah, that's true- you know volume of one cylinder, (diameter x stroke) and compression ratio-

from that, you can calculate the head volume with whatever piston features are built into it- that
reverses out of the compression ratio. Including deck height.

Then just add the volume that the thicker head gasket gives you, and recalc the
ratio that way.

Probably more accurate than trying to measure chamber volume and piston crown
volume.

Hadn't thought of doing it that way, but it makes good sense.

t

[silverm3bmw]

I understand what he is saying but if the engine has never been touched, then one should have everything. If one is not sure the engine is decked or planed in any way, or they are trying to raise compression, then you need to take it apart and physically check it to make damn sure. Maybe someone can answer the mans question???