nomorews6

iTrader: (7)

I just had a quick question - on a 408, what would the horsepower difference be between an 11.1:1 vs. a 10.9:1 - I was wanting a -10 cc piston, but all the shop has in stock now is a -12cc piston. I already have tsp prc 62cc 5.3 2.5r heads. should i wait for the other piston or will it only be worth 2-3 hp?

1997bird

iTrader: (2)

As long as they are only 2 cc differance and the same material, I say mill the heads 2cc and go racing.

mrdragster1970

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Less than that, don't sweat it. Compression does equal more HP, but 0.2 is not worth a second thought. 1, 2, or 3 full points will make a difference, not 0.1, 0.2 or 0.3.
Have fun, good luck.

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LiENUS

These are reverse dome I'm assuming right? I'd look to see what the dome looks like on both pistons and whichever matches the combustion chamber on the head closest, go with. the .2 in compression won't matter much but flame travel will. if the -12cc piston matches the combustion chamber closer than the -10cc then youl'l find more power with the lower compression.

Steve Bryant

iTrader: (1)

I agree with mrdragster1970. A couple of tenths of a compression point or so won't make any real difference in power. Save the milling for another day when you might need to clean up the deck surface or if a little bit of warp develops in the future. If the head decks are flat, I wouldn't mill them.

Steve