I don't think there is a calculation because it's based on a lot of factors. For example 12.5 would be fine if you pulled enough timing.

 

lol, depends on what accurate means I guess. If your talking real world hp numbers then no. just look at some of the dyno's from a dynapack, its more like crank hp than anything. If your talking tunability and accuracy between runs, etc then yes. Superflows are crap too, so are dynojets.

 

[QUOTE=ShocK,Apr 2 2008, 01:20 PM] lol, depends on what accurate means I guess.

 

12.5:1 is fine on 93 octane, as long as the tuner knows what he's doing.

 

Great link... Does he still post around here?

 

http://www.j-garage.com/form.htm

They are a little over $150 each. There are three pistons based on slight bore differences. If you have a relatively new motor I think it would be safe to look at your pistons through the spark plug hole and just copy what you have already. If your motor is pretty worn though I don't know if that is the best thing to do, you may need to actually measure.

I'm going to do this mod.

 

Toda spec C's only made 8WHP with cam gears and 109 octane.

The JDM ap1 pistons will get you to 12.65:1.

 

What shop would you use in SoCal to replace pistons?

 

It is going to be an arm and a leg, basically overhauling the whole engine........ save it for more engine, stroke it while you are in there.

 

I was budgeting around $1000, maybe more?