Thread: Engine compression = H.P.?

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Is there a rule of thumb for H.P. increase with the increase of compression??

I'm building an engine (302 HO) and can get std. 9.0 comp. pistons for $90.
If I jump to 10.2 comp. the price goes way up!

I'm just wondering if the H.P. increase with higher comp. is worth the price?

The car is a 32 roadster with an AOD-E trans with 2000 stall and a ford 9" rear with probably 4.10 gears if this helps in the equation.

Maybe the cheaper one is a cast piston? I know the 5.0 has used both cast and forged during it's lifespan. FWIW get the forged and yes they are more expensive but well worth it. G.

Both pistons are Hypereutectic.

I'm just wondering what amount of power increase is expected for a jump in compression by 1 point?

You will go up power doing that. But this may lead to other problems, make sure the other components of the motor are ready to handle this, may lead to haveing to throw extra money into it. Also be carefull with valve clearence, had a friend make a mistake before in a Mustang.

10 h.p.?
30h.p.?
100h.p.?

If I can gain a lot of h.p. on comp. then it is worth spending a little more to make the h.p.
If it's only 10 h.p. then I will go for the lower comp. and find it elsewhere.......

Correct me if I am wrong but I also think it's more low end torque and power gained, more for towing or we used to try to get as much as we could on the circle tracks when we were racing for off the corners until they started checking more, lol. There is more effective ways to increase hp at low bucks then this and all the work it is.

Thanks........That helps make my decision.

I think I'll stick with the 9-1 pistons and work on getting some good heads.