is there really a significant power gain using high CR pistons for boost?

thinking of trying out 12.xx:1 CR on a bseries 900whp engine.
i am constantly reading plugs and it does not have any sign of detonation @ 10:1 CR @ 38psi.

just want more power for the same setup, and I have some NA 12.xx pistons available...

anyone running high compression pistons? any gain as a direct result from swapping the pistons?

 

I dont think you want to just throw NA high compression pistons in there. I think the piston design is different, an expert may want to chime in.

Aside from that, I had good results from a 11:1 turbo setup, it seemed like it spooled up quicker than it probably would have with a lower CR.

 

What fuel?

 

Think of it this way. You get your final pre-ignition pressure from both the turbo increasing psi and the CR. Once it is boosted and compressed mechanically, it doesn't matter where it came from, 1psi boost and 40:1 CR or 70psi and 8:1 CR. What does matter is how much you are asking of your individual cylinders.

Let's say both those setups produced the same FINAL pressure and are both in a 2.0L motor. If that cfm with appropriate fuel is good for 400hp, you are asking for 100hp from each cylinder. In the first setup you have 12.5 ml (500/40) to make that 100hp. That's a lot of force in a pretty small space. In the second setup, you have 62.5 ml (500/8) to make that same 100hp. I'm not positive if those two setups are equivalent, but you get the idea. There is a point of diminishing returns which honestly, seems to be around 10:1 (Methanol). And since methanol has a lower A/F ratio, more liquid fuel is appropriate for the amount of air you can squeeze in. And the more fuel at an appropriate a/f means more BTUs.

Help at all?

Also, 38psi at 10:1 is 380psi pre-ignition. 12:1 jumps to 456psi, a FINAL increase of 76 psi. If you increase boost to 46 psi in your current setup, the final psi, pre-ignition will be the same.

Engines are air pumps. CFM makes hp, fuel just has to be appropriate. Push more air in and you get to get to add more fuel, with increasing the CR, you don't get to add any.

 

yeah, i pretty much understand where the computations are coming from. But like I said, its purely theoretical.

i guess what i'm asking for is, is there anyone that tested a piston-only-swap-then-dyno-right-away test? if I can gain about 50hp by increasing the CR by 1, then i'll go for it...

http://www.modularfords.com/f17/incr...ressure-51059/