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Need help determining exact compression ratio.
Posted: Oct 27, 2006 9:27 PM
by GregATL
Sorry to burden you folks with this but I do not have acces to the data I need to figure this out.
B34 engine with B35 head. Machine shop milled .008" off head when resurfacing. MLS head gasket. I don't know the exact thickness of the head gasket. Maybe TCD can chime in on this issue.
Also, how much will timing be affected by the thicker gasket.
I am just curious and would like to know. Thanks.
Posted: Oct 27, 2006 10:04 PM
by russc
Timing wont be enough to even consider from head gasket.
RussC
Posted: Oct 27, 2006 11:09 PM
by wjones
Without knowing the MLS thickness it's a wasted excercise. The .008" is very little volume and it will make little difference. I believe the hearsay number for the b34/35 combo is 7.5. My estimation for a .120 mls in addition to a b34/35 is just under 6.6.
Posted: Oct 27, 2006 11:49 PM
by T_C_D
Gasket is .080
Posted: Oct 28, 2006 2:29 PM
by GregATL
Well the info is starting to trickle in.
MLS head gasket .080" vs stock at ? Thanks Todd. I believe this is compressed thickness. Correct?
Does anyone know the volume of the combustion chamber on the B35?
How about the volume of the piston recesses on the B34?
And finally the squish area of the piston. Or how far below the surface of the block the piston is @TDC.
My car is currently running well with this setup but is obviously quite slow. Not really noticably slower than stock but slow anyhow.
Again thanks for the info and I will let ya'll know what I come up with in the end.
Posted: Oct 30, 2006 2:46 PM
by gol10dr1
i believe 1mm milled from the head raises the compression .5 so 1mm off the head could raise the compression from 8.0:1 to 8.5:1.
Posted: Oct 30, 2006 8:59 PM
by GregATL
O.K. I finally got off my ass and worked this out. Bear in mind that my results are not typical. Some side effects may occur including increased drowsiness or hypertension. Vomiting, although rare, can occur as well as dizziness.
Really though here is what I've come up with;
Stock b34 clearance volume 81.59cc
B35 head milled .008"on b34 block with MLS head gasket .080" clearance volume of 89.45cc.
Swept volume of 571.7cc per cylinder.
571.7 +89.45 = 661.15cc / 89.45cc = 7.39:1 CR
I don't expect that this number is dead on just very close.
I hope this info may be useful for someone else in the future.