Compression calculations

-
replicaracer43

replicaracer43

Grumpy Old Man
Joined
Oct 10, 2008
Messages
6,051
Reaction score
7,867
I know there's alot of members on here way sharper than me, so maybe one of you can help me out with some math. I have a stock stroke 340, .030 over which is 4.070 bore, trying to figure the compression ratio. We have a 71 cc chamber, a .039 compressed gasket, a .016 positive deck piston which has a dome. The dome measures 11 cc, and the valve reliefs measure 9cc, can anyone help figure this? Thanks in advance!
 
I know my Pistons are flat tops with reliefs and 4.040 bore and about 5 cc's above deck. 71cc open chamber head and the manufacturer calculate 11. 3 to 1.
 
replicaracer43 said:
I know there's alot of members on here way sharper than me, so maybe one of you can help me out with some math. I have a stock stroke 340, .030 over which is 4.070 bore, trying to figure the compression ratio. We have a 71 cc chamber, a .039 compressed gasket, a .016 positive deck piston which has a dome. The dome measures 11 cc, and the valve reliefs measure 9cc, can anyone help figure this? Thanks in advance!
Click to expand...

Do you know top ring down? Deck height?
 
Last edited:
10.494:1 You have to add those 9cc's of valve reliefs to the chamber volume. Once you do that, it's pretty accurate.
 
I took my shoes and socks off so I could use my toes for counting and came up with 10.49 to 1
 
You must log in or register to reply here.
-

Back
Top