Piston surface profile

Curious.....

It's often said that the piston top profile should not have any edges as these will heat excessively and cause pre-ign.

But have a look at the piston from a 360 - it has lots of edges.

So why are these not causing problems ?

That piston bowl is designed to guide the mixture in the cylinder. I don't know the specifics of that engine, but they don't spend money on a complicated design like that for nothing.

The preignition can be reduced by cold plugs and reducing carbon deposits. Often the carbon will build up on edges and flake off.

Sharp is really a relative term. You'll notice that all the edges on that piston still have a slight radius on them.