4SFEDZ

iTrader: (6)

ok, im doin a rebuild and need help on figuring my cr! i have a 4.04 bore, 58cc heads, 3.75 stroke (385 ci) and flat top pistons, no valve release, and my piston at tdc is .200 in the hole! so if i could figure out how many cc's .200" with a 4.04 bore is i could use that figure as my valve relief and figure my cr with a certain head gasket thickness. does this make sense? lol!

NemeSS

iTrader: (127)

.200 in the bore doesnt sound right. 0_o
what is bore and compressed thickness of gaskets used?

4SFEDZ

iTrader: (6)

bore is 4.04, not sure on gasket, trying to see what thickness to use. this is not an ls motor

NemeSS

iTrader: (127)

sound like sbc/lt type build
ur gonna prolly want to run as thin as possible gasket with piston being that deep bore in the hole.
i have always like to kept 0 deck for sbc/lt at least.
and always minimum
+.010 protruding for ls motors
what gasket u plan on running? its not gonna be same as bore of block. has to be bigger.
assuming u were using a theoretical 4.125 bore by .030 compressed gasket: the above engine specs out to around 8.39:1 scr

4SFEDZ

iTrader: (6)

ok i think im on the right track,

cylinder volume, http://www.online-calculators.co.uk/...ndervolume.php

convert cubis inches to cc's, http://wiki.answers.com/Q/How_many_c...are_in_1000_cc

NemeSS

iTrader: (127)

the piston being that deep in the bore at tdc may affect quench distance.
i like to keep quench in engines ive put together around .035-.040 at least for all builds from n/a to psi
but thats just me

4SFEDZ

iTrader: (6)

ok i found this

http://www.csgnetwork.com/compcalc.html

and yea that was my next question, i prolly need to go as thin on a gasket as possible, what the thinest i should go? and yes its a lt build. im plannin on runnin 20+psi of boost,and race gas. im not to familiar with quench!

NemeSS

iTrader: (127)

the above calculator is pretty accurate. same numbers i got. i figure my scr and dcr by hand with sheet of paper and calculator. i also figure rod/stroke ratio, quench, amount to mill heads, dcr if have cam card etc. i havent found online calc. yet that has all those features.

4SFEDZ

iTrader: (6)

hmm, thanks for the replies, what gasket you recommend? felpro or cometic? also would there be any disadvantage of running the thinnest gasket possible? i just need to figure out my piston to valve!

NemeSS

iTrader: (127)

prolly thnnest mls u can get. bore doesnt really matter as long as its bigger than 4.04. i dont think u will have too many ptv clearance issues with the piston being that far away at tdc. lol
i always keep at .100 minimum for ptv clearance for both valves
.200 is dam way in there. i dont think ive ever heard anyone going with the piston that deep in the bore.

mwg2600

It sounds like you have the wrong rods.

Wicked94Z

iTrader: (26)

yea running a 6" rod piston on a 5.7" rod? that's the only way i see this happening...

KCS

iTrader: (20)

20psi? It'll be fine. For some reason, boosted engines don't really like quench. They tend to make power when you run quench REALLY loose, but I don't. .200" sounds excessive, but I don't think it'll hurt anything.

Got any part numbers on your piston/rod combo?

bww3588

iTrader: (49)

.200 in the hole is beyond unexceptable. with your 58 cc heads, your going to have a 92cc's above the piston @TDC without the gasket....with the excessive quench volume, that flame is going to be so weak, even under boost.

KCS

iTrader: (20)

That's the point. Heavily boosted engines typically don't like quench. I agree that .200" is a lot, but what I'm saying is that I don't think it's going to hurt anything since he is planning on 20psi and race gas.

NemeSS

iTrader: (127)