Piston Design = Power?

Aside from the static compression ratio, would an OEM piston make less power than an aftermarket piston with the same CR?

I actually have no idea, but to get this thread rolling I’ll say that the shape and location of the divets on the top of the piston can effect the efficiency and completeness (if that’s a word) of the combustion. Therefore, the piston with more R&D put into it to make this all happen will produce more power.


I agree with what Ben said, but aftermarket pistons can be lighter wieght and more durable than an oem piston. If they are forged or any other type of material they’ll be stronger and lighter…then i would think even if the cr are the same, that the aftermarket piston would not necessarily give you alot more hp’s, but would be more durable/stronger for future mods, etc.

The aftermarket pistons have some cool aspects such as a stronger metal, not the softer stuff the OEM pistons are made with.
The OEM pistons have pins that are pressed in and dont turn as to where the aftermarket ones are free floating with bearings to give you easier rotation and yield a few more hp’s.
The CR is pretty much determined by the height of the piston. The more room it takes up the more CR you will have because it shrinks the combustion chamber. Pretty much the same theory as welding the combustion chamber in the head…

ryuyszh - If you meant the 4 divets on the piston, those are just there so the valves dont hit them.


Thanks everyone, I’m trying to source parts for a daily driven B16A and wondered if I should even bother with forged pistons. I think I’ll just stick with stock pistons for now.