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I think my machinist might have taken more off the old block than what he was suppose to giving me a bit less deck height than I probably should have. I am posting this here as most wont see this in my build thread and as always, I appreciate the help!
Well, I took all of my measurements for my final compression ratio and it came out like this:
Bore 88mm / 3.465 in
Stroke 94mm / 3.7 in
Head 43 cc's (I am going to triple check this tomorrow after work)
Deck Height 0.014 in
Piston Valve pocket -2cc
Stock Felpro head gasket 0.016 in
When I enter all of that into CFM's Cometic calculator and zealautowerks calculator I get 12.51:1
However Summit Racing outputs 13.5:1 and when I calculated it out by hand I got 13.5:1.
Why am I getting lower numbers using their calculators?
If the 12.51:1 compression is the correct one then I should go with a .045" Cometic gasket to get 11.56:1.
How do I lower the compression enough if 13.5:1 is the right compression?
- Messing with summit's calculator, it looks like if I machined the top of the pistons to have 0.032 deck clearance and used a 0.050 Cometic I would be at 11.64:1 but at that point it is more than doubling the piston to deck height and using one of the thickest gaskets I can find. Perhaps increasing the combustion chamber volume would do the trick?
My goal is a safe engine with useable power on 93 octane
Well, I took all of my measurements for my final compression ratio and it came out like this:
Bore 88mm / 3.465 in
Stroke 94mm / 3.7 in
Head 43 cc's (I am going to triple check this tomorrow after work)
Deck Height 0.014 in
Piston Valve pocket -2cc
Stock Felpro head gasket 0.016 in
When I enter all of that into CFM's Cometic calculator and zealautowerks calculator I get 12.51:1
However Summit Racing outputs 13.5:1 and when I calculated it out by hand I got 13.5:1.
Why am I getting lower numbers using their calculators?
If the 12.51:1 compression is the correct one then I should go with a .045" Cometic gasket to get 11.56:1.
How do I lower the compression enough if 13.5:1 is the right compression?
- Messing with summit's calculator, it looks like if I machined the top of the pistons to have 0.032 deck clearance and used a 0.050 Cometic I would be at 11.64:1 but at that point it is more than doubling the piston to deck height and using one of the thickest gaskets I can find. Perhaps increasing the combustion chamber volume would do the trick?
My goal is a safe engine with useable power on 93 octane
