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Looking to change heads to an 11 degree head for more piston to valve clearance and mill the heads a bit to about 66cc to be safe, and use a .041 thinner gasket vs stock.This would be on pump 93 only and have to avoid flycut on pistons.
Are the below dome 0.00 and deck clearance -.006 out of the hole, numbers be accurate?
They are correct, but Summit's calculator doesn't take into effect the gasket bore diameter nor the ring land volume. Most likely to err on the side of caution, as compression will actually be a bit lower with those items included.
They are correct, but Summit's calculator doesn't take into effect the gasket bore diameter nor the ring land volume. Most likely to err on the side of caution, as compression will actually be a bit lower with those items included.
Would you know how to calculate dynamic compression?
I am trying, but seems like it comes back too high for me.
You need advertised duration numbers to be able to calculate dynamic compression. That's why your calculations are coming out incorrectly. Call GPI and see if they can give you the advertised intake closing value.
You need advertised duration numbers to be able to calculate dynamic compression. That's why your calculations are coming out incorrectly. Call GPI and see if they can give you the advertised intake closing value.
Your engine doesn't build compression until the valve is fully closed, so between .050 lift and the valve fully closing, no compression is being created. Even the .006 advertised values don't account fully for the valve being completely shut. But they're better than nothing. However, you're looking at approximately 50 degrees between @.050 and the .006 advertised point. That's 50 degrees LATER after BDC that the valve fully shuts. It will make a significant difference in your calculations.
You need advertised duration numbers to be able to calculate dynamic compression. That's why your calculations are coming out incorrectly. Call GPI and see if they can give you the advertised intake closing value.
Did they give you the advertised intake closing point? That's what you're building your DCR off of. You could guess by adding 26 degrees to the @.050 number, which would give you 68.6 degrees ABDC, but a lot of cams these days are asymmetrical and that calculation wouldn't be exact.
03-15-2024, 11:12 AM
Compression calc stock bottom end LS3 on 93 pump. 
