How much more horse power per Compression point added?

[Anonymous]

Anyone know approx. how many whp/wtq is gained out of every point added by compression?

Thanks

[robtec]

i think its 10% to 15% per point,i see this in some page ,but i not remember what was the page 8)

[Calesta]

Dude... I should be putting out 250whp then. :P

The general rule I see people going with is about 4% for each full point increase in compression.

[Steve91]

It's not an automatic gain of a fixed amount. Camshaft profile has alot to do with it too. A radical cam with lots of overlap will make much more power in a high compression motor compared to what the same cam would do with low compression.

What CR are you planning to run and with what cam?

[Anonymous]

What CR are you planning to run and with what cam?

im looking to run a1 pistons (12.6:1) w/ a crower stage 2 cam, valves, springs, retainers

[builthatch]

There are too many variables to go by a supposed set formula for determing gain per cr point...a 11.5 cr y8 wiht a stock cam will make hella less power than a 11.5 cr y8 with an appropriate cam upgrade...

[Calesta]

It's not an automatic gain of a fixed amount. Camshaft profile has alot to do with it too. A radical cam with lots of overlap will make much more power in a high compression motor compared to what the same cam would do with low compression.

Of course- but with all other factors kept constant, 4% is the general rule. When you start changing other things in the engine, there's no way to tell.

[Sushiboy]

How streetable is 11.5:1 compression, though?

[Anonymous]

when I get around to having that kind of money, I want to put crower 10.5-1 pistons in my y8. I have NO IDEA how much hp that will give me with a crower #2cam and p&p. BUT I'd like to hope for 150 at my wheels.

Plus its streetable and would be tuned by apexi vafc.

so, we'll see I guess

[SOHCcommando]

How streetable is 11.5:1 compression, though?
i have a friend thats running about 11.75:1 on the street daily.

[Calesta]

I used to run 12.6:1 on 93 octane pump gas, and that lasted for 45k miles before stupidity came into play and I blew up the engine. The new build is slightly lower compression, but I'm still running somewhere between high 11s and low 12s for compression.

[fjt]

So thats might be my problem for not putting the numbers i expected..The cam..

I had 12.4:1 compression and now i lowered to 11.8:1 with a thicker head gasket..I drive my car daily.

[Anonymous]

I used to run 12.6:1 on 93 octane pump gas, and that lasted for 45k miles before stupidity came into play and I blew up the engine.

What did u do to blow up the engine?

[Calesta]

Downshifted running way too high of a speed... jerked the engine up past 9000 rpm, so basically a mechanical overrev. The engine had been up to 9000 with no problems before, but not from the transmission ramming it up there. The rings on piston #4 decided not to stay in place any longer, and the top ring went through the bottom ring land. Fun fun fun!