Input on custom forged pistons please

[ezzzzzzz]

I'm close to having all the pieces needed to build my supercharged 2.9 using the LD block, LD crank, L20B rods and P90A mechanical lifter head. I figure to use a stock L28ET headgasket. The SG is a roots style Eaton M62. It will be injected and controlled by a SDS EMF-6 setup. The last major item required to build the long block is the custom forged pistons. I have 40.05 compression height to work with. The pin is 21mm. Should I look at reproducing the land thickness and ring type of the L28ET? The pistons in the L20B have very thick rings which might be better suited to a SG? How about skirt length? Anyone who has piston specs from their builds and is willing to share that info would be greatly appreciated. The compression ratio I'm looking for is around 8.3 for 5-8 psi boosting. I've never bought truly customized pistons so it's a very foreign place for me. Thanks for any help on the subject.

[1 fast z]

Usually skirt length is determined by the manufacture, and they fit it into the piston after all of your other dimensions are met. As for ring thickness, I would use a dual chrome steel setup, with 1.0-1.2mm compressin rings. I would also use a 3mm thick oil controll ring. Place them as far down the piston as feasably possible, as this will protect them from detonation. MAKE sure you get an exact reverse dome to YOUR exact P90 head. This needs to be done by getting a thick dome on your piston, which you need to specify to your piston manufacture. So say you need a 12cc dish, you calculate the area of the P90 chamber then calculate the volume needed for that area to get 12cc's then that will be how thick you need the dome. REMEMBER you need atleast .200 thick in big areas on the piston and about .150" in SMALL areas, or you will burn a hole in a piston. As for pins, with that big of diameter pin I would go with a .090" wall tool steel wrist pin. I would recomend double true arc rings (internal snap ring) for the pistons. Thats just some of my advice and experence, and I use these guidlines to build my motors.