Hello,

I was wondering if anyone has any thoughts or ideas on how much power can be gained by increasing the stock cr of 11.0:1 to say 12.5:1 using the stock bore. Is this something worth doing in which a lot of power can be made? for a fully bolted on motor on pump gas vs the same setup but with 12.5:1 cr what would be the hp difference/gain roughly? thanks in advance

 

All other things equal and stock cams, about a 3%-5% overall WHP gain.

 

Unless you already have the engine apart to rebuild it, it would not be worth it. Even then, 12.5:1 is a little on the high side. 11:1 is plenty for pretty much any setup. I would spend my time elsewhere. Porting, cams/valvetrain, header, ported IM, etc.

 

Cam upgrade will be a must for noticeable gains tho.

 

You can dump all the money you want with very little return in hp no need for cams and pnp
Just go boost

 

thanks for all your replies. i already have a built and boosted one. i want an all motor build that can get me in the high 12s with slicks

 

Just a suggestion, you can sell your B series and get and H23A blue top and go H2B. Stock block with I/H/E will get you in the 12s if you have the right chassis and tires.
If you aren't willing to part with the B series I understand, but really that H2B set-up is going to be a much better bang for the buck. My CRX with full interior runs high 12s with just regular street tires and a less that great driver (me). This is just a suggestion, but if you decide to go this route I doubt you will be disappointed.

 

Don't run 12.5CR with stock cams, unless you have 100+ octane

 

Done people claim 10whp per point in compression raised...