Say you have a worked head with a chamber that allows around 12.5:1 static with a 0cc flat top piston. If you want to run around 11.5:1, you can only use a dished piston (I don't know how much troph reliefs affect the CC). Would you run a full round dish, or something like an ovaled dish so you can have a bigger quench area?

 

In the bike engines we build we use a dish that mirrors the combustion chamber.I have heard claims that a hemispherical dish will make more power than a flat floored dish.

 

Use a spherical dish.

Cosworth now uses it. Back in da day MAX_CFM sucessfully made spherical dished pistons to run lower compression (and it picked up a couple) on Cup motors. CP Pistons has this too, e.g. SC7017 has a spherical dish.




Modified by Don Lackey at 5:50 PM 3/15/2007

 

I would match the chamber also. Not exactly an oval, but close, depending on the head.