Teach me about piston shapes

[bacon K5]

I know the basics around domed, dished, flat, etc, but what is the significance of all the other geometry? Some have full skirts, some are mostly open, and some have what seem like specific ports/pockets milled into them.

What's important and what isn't?

 

[Guido Salvage]

Most are round...

 

[GPX433Todd]

And some are shaped like a livestock tank.

 

[big hank]

Usually they're round.. Definitely not square or triangular

 

[Nitroman]

Diesel pistons are even more interesting.

 

[apemoreton]

They all go up and down. On serious note a closed port saw will need a windowed piston and a open port won't.

 

[Chris-PA]

They all go up and down. On serious note a closed port saw will need a windowed piston and a open port won't.

It's more complicated than that. Closed port bottom fed does not require a windowed piston. Open port could use either.

 

[bacon K5]

Since this thread has been largely useless up until now, I did some more research and I think the open/closed port issue is what was confusing me. I think i uderstand that now, but look at this 576xp piston...looks like a weight reduced non-windowed piston, but it runs in a closed port cylinder. Does that mean its bottom fed? What is the significance of the smaller pocket on top with the hole in it?

 

[bacon K5]

Unrelated to porting, why do some model saws have both single and dual ring pistons available for them?

 

[wcorey]

 

[Chris-PA]

Since this thread has been largely useless up until now, I did some more research and I think the open/closed port issue is what was confusing me. I think i uderstand that now, but look at this 576xp piston...looks like a weight reduced non-windowed piston, but it runs in a closed port cylinder. Does that mean its bottom fed? What is the significance of the smaller pocket on top with the hole in it?

That's a strato piston. The lower pocket connects the air intake to the ttransfers and is a different thing than the windowing in older designs.

 

[o8f150]

i have the best luck with the octagon shaped piston

 

[pioneerguy600]

i have the best luck with the octagon shaped piston

Here I always thought you ran square Echo pistons.....LOL