What is the reason behind that forged pistons have 1/16" top ring why normal hyper pistons have 5/64" rings?

Edit: corrected size.

 

Less Friction..which equals more HP

 

I think you must mean 5/64", and I'm pretty sure you can get either type of piston with whatever ring sizing you desire.

Forged pistons do have a greater expansion rate, so there are considerations to clearancing.

 

You can get pretty much any piston material in any ring width you want on a small block Chevy. Thinner rings are generally lower friction but it's their WEIGHT that is the biggest difference. In high RPM applications thinner rings have less tendency to "flutter" and lose seal at higher RPMs. That's why higher performance stuff will usually use thinner rings. Friction has more to do with the tension of the rings. GM has used low tension rings in most of their motors for more than 20 years now. Then they went to metric rings, which are about equivalent to 1/16" rings in thickness.

 

Yes, I meant 5/64", sorry. Also corrected in the first post.

Thanks for all the replies!