on a 9.5:1 motor, how would 195 rounded psi be....?....help?

 

It think a litle high that would be about 12.24:1 psi

Here is how I figured it & why:

Room ATM is about 15psi, (actually 14.7psi) if you cut the volume in half that works out to be about 30 psi. But since we started at 15, you would only read 15.

Therefore if you take 195 - 15 = 180 & divide by 14.7 you would get 12.244897:1 compression.

It works out about right. By Riv is 10.5:1 and the compresion reads around 170psi of pressure.

so (psi-15)/14.7=compression:1

Just a guess though

John

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G O D BLESS AMERICA

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Unfortunately, you can't directly calculate the compression ratio from the compression gauge reading. I have an 11:1 CR in my 355 (calculated using cc of heads and pistons) and my compression testing gave me 225 psi. I'd say 195 is probably closer to 9.5:1, but the duration of the cam also plays a part in the compression readings you'll get.

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Greg Westphal
'87 IROC 355TPI/A4