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Thanks a lot for all the replies


Dogdays,

The pistons are flat ,stock style,TRW L2388,0.75" comp distance .
The deck is not exactly the same in all the cyls,but they are between .068" wich is the one most closer to the surface and .074" that would be the most deeper in the hole.
The Whiplash cam lift is .518".

What i thought,or at least what i have read in some web page, is that the Alu heads subtract one pound from the compresion,but they compensate that loss of power in other ways.
So if it is 9.30:1 would it go to 8.30:1?
]

The guys here will correct me if I'm wrong, but I think it's not that aluminum lowers compression, but more like you can run more compression with aluminum than an iron head without detonation, all things being equal.