40thou Pistons

[drgnball34]

thinking of geting 40thou pistons since my RB25DET engine is stuffed. Does any1 know what compression my engine would be using standard gasket? What thickness gasket would be ideal? I have GCG highflow with cams and should max at at around 18-19psi. I want the best engine response possible.

[Abo Bob]

Depends what brand they are but when you increase the bore size you increase the compression ratio.

Are you doing any head work?

I had some fairly minor head work done, 87mm pistons, stock thickness head gasket and ended up with 8.75:1 CR. Which I quite like. It's almost as high as stock (9:1) so the responsiveness is there but being a fraction lower I think makes it easier to tune and a little safer with regard to detonation.

Basically I told the engine builder what CR I wanted and he worked the head to achieve this with the chosen pistons and head gasket.

[drgnball34]

Depends what brand they are but when you increase the bore size you increase the compression ratio.

Are you doing any head work?

I had some fairly minor head work done, 87mm pistons, stock thickness head gasket and ended up with 8.75:1 CR. Which I quite like. It's almost as high as stock (9:1) so the responsiveness is there but being a fraction lower I think makes it easier to tune and a little safer with regard to detonation.

Basically I told the engine builder what CR I wanted and he worked the head to achieve this with the chosen pistons and head gasket.

Im going ahead with a set of wiseco 20thou. Very cheap for $1100 i'd say. Since the rods are GTR, a fresh set of rod bolts and big end bearings and it should all be reliable enough to handle 350-400rwkw? 1.2mm gasket gives standard compression using standard pistion size and 1.6mm gives 8.6. So using 20thou and 1.6mm should give 8.7 -8.8 comp? and I also have NOS..will this effect engine realiality provided power is keep within the limits?.....I will be using ARP head studs to hold the head down.. if that is even needed.