if i had a b18c1 engine and i used jun stage 4 camshafts with ctr 81.5 pistons would it be ok? any problems? also, whats the difference between junstage 3 and junstage 4 camshafts?

 

Type 3
INTAKE lift - 12.0 mm, duration 265 @ 1mm (Advertised 304)
EXHAUST lift - 11.5 mm, duration 265 @ 1mm (Advertised 304)

- Type 4
INTAKE lift - 12.5 mm, duration 265 @ 1mm (Advertised 304)
EXHAUST lift - 12.5 mm, duration 265 @ 1mm (Advertised 304)

Those are the specs for the type 3 and type 4's so you could see the difference. They have the same duration but the type 4's have a little more lift on both cams. I know the type 3's like somewhere around a 12:1 compression ratio, but im not sure about how much more compression the type 4's like.

 

pk 81.5 is bore size but that doesn't really matter. To answer your question yes your pistons will handle a cam upgrade just fine. What you should worry about is valvetrain. The difference between the two cams is that the stage 4 cams have a higher lift and longer duration than the stage 3's due which means more power. But if the cam lifts too high than you got valve float. usually if a cam lifts higher than .500 than your going to have valve float on stock valvetrain. To stop this you have to get new valve guides put in by a machinist. Have fun sounds like a nice setup.

I'm also running a b18c1 and going w/ Skunk2 stage 3 cams. Give further updates when you get those cams installed though