well my engine is assembled and ready to drop in butI decided to call jegs to see what type of compression I am running with thepistonsmy local shopinstalled. THey say it is 10.8 to 1 and this kind of made me angry sinceI told the shop I wanted it under 10 to 1, to run premium gas. I called the shop and they still claim its 9.8 to 9.9. How can I figure out the compression of the engine?

 

Only the person building the engine can tell you what the measured compression is. Everyone is just quessing based on numbers available. Did you tell Jegs what head gasket you were running? If not thier number will be high because the prob didn't take it into account. Did you tell jegs how far in the hole your piston is?

If you want to know, disassemble it, CC enverything, measure the gasket, measure how far in the hole you are and then do the math.

10.8:1 even if accurate, is not too much compression for premium fuel. Depending on the cam chosen actual compression would/could be lower depending on valve overlap.

 

you could do a compression check with a compression tester. it plugs into the spark plug hole.