using b series pistons in b20a

[mykwikcoupe]

I know that carotman is using them but I never heard how using a different style piston affect compression ratio. What I trying to do is source an off the shelf piston with a 81mm bore and around 9.5:1 compression. Ive looked on raceeng.com and they list quite a few for the b18 and b16 but im not sure if I have the piston pin redrilled to fit the rod, or even if it matters. There site isnt very informative on piston design so Im not sure if the pistons have a different deck hieght or not. Thanks for the input. Mike

[thegreatdane]

why cant you just get B20A5 pistons at your desired c/r?

[mykwikcoupe]

That is actually what Im looking for but the stock shelf items are currently 9.0 or 10.0:1 CR. I think one will be too low and the other too high. If all else fails shoot for the moon. Im still trying to source other venders at the moment. Im sure someone has a stock CR pistons in an aftermarket format. I was more curious what would happen as the newer b series engines have a ton of options at there disposal.

[TWOLOUDNPROUD]

Carotman used P73 pistons in his B20a but his rods where the 20mm and he had them bored to 21mm to fit the piston pin.

[thegreatdane]

That is actually what Im looking for but the stock shelf items are currently 9.0 or 10.0:1 CR. I think one will be too low and the other too high. If all else fails shoot for the moon. Im still trying to source other venders at the moment. Im sure someone has a stock CR pistons in an aftermarket format. I was more curious what would happen as the newer b series engines have a ton of options at there disposal.

It's only a little extra to have them make pistons at the c/r you need and doesnt take very long either.

[RobT5580]

I ran the Wiseco 9:1 and it seemed fine for what your looking to do.

Just watch raceeng because my last set i got a stock bore 81mm piston since i resleeved my block but the rings were not up to par to hold boost. I liked the XC rings and i plan to go back to that setup since it sealed well for the short time it did last. The 81mm smoked from day one.

[rjudgey]

Just use the 10:1 CR pistons then have your chambers flowed, bore matched and valves unshrouded then it will be more like 9.5:1 or a bit more depending howmuch you take off the face as well. Or have a small dish machined in the crown of the piston. Running 10:1 isn't much more than stock so really shouldn't be too much if your planning on running turbo you can reduce it later via the heads chambers as mentioned.