how much gain would i be getting in compression going from a lq4 piston to a -4cc mahle flat top piston..roughly how much hp gain is this..how big of a shot would this be able to handle?? thinking 225-250..possibly more?

 

the only concern would be the rods, Im sure it would hold that progressively controlled

 

gettin h-beam 6.125..and the heads are ported ls1's with a 66cc chamber and using either .030 or .040 cometic head gaskets

 

Which casting? 2618 or 4032

 

Compression comes out to 10.062 ish... I think, someone with a clue might want to double check me....

 

4032..which one is better

 

In very short form...
2618 = Very strong, will take allot of pressure, shorter life, I have heard they tend to ratle a bit more, because of the extra clearince need to run them
4032 = Not as strong, but longer life, also quiter

 

how much do you think i could spray them?

 

I have no idea. all the research I've done makes the 4032 sound like a slightly stronger than stock piston, so I'll be running the 2618's in my engine. check out LS1tech side, there is A TON of info on pistons over there.