Originally Posted by markdunlap
I believe SRP pistons are 4032 alloy for small blocks and flat top BBC but are 2068 for high compression BBC. I have 2 sets of 496 pistons here and it says on the box and paper work they are 2068. They are a little heavier than the JE and less compression 12.7 versus 13.5 but other than that they are just $200 cheaper.
Are your gapless rings top land or second land gapless? Top gapless should leak 2%.
Have you talked to a tech guy at TOTAL SEAL about rings? Has your engine builder?
I have built some alcohol engines both naturally aspirated and blown and the rings and cylinder wall prep was only difference per TOTAL SEAL specs.
I have had to file fit gapless rings as they were not in the range of .010"-.040".
I have also had a guy switch back and forth on a carburated engine and saw no differece as far as blowby. His engine did not have gapless rings.
Mark, i'm glad you posted that number, i wasn't even aware of the change from the 4032, so i did a lttle research. It appears that the 2068 is not a lot different than the 2618 mat'l, but a lot different than the 4032 mat'l. The 4032 having 11%to 13% silicone compared to 0.7% of the 2068 mat'l, and .025% with the 2618. Chemical composition comparison posted below.
Zip.
2068 alum.
R.R.56 [1]
Melting point 635°C
Density 2.75
Composition
Copper 2.0%
Nickel 1.3%
Magnesium 0.8%
Iron 1.4%
Titanium 0.1%
Silicon 0.7%
Aluminium 93.7%
2618 alum
Chemistry Data : [top]
Aluminum Balance
Copper 1.9 - 2.7
Iron 0.9 - 1.3
Magnesium 1.3 - 1.8
Nickel 0.9 - 1.2
Remainder Each 0.05 max
Remainder Total 0.15 max
Silicon 0.25 max
Titanium 0.04 - 0.1