not 100% accurate by any means,but a very good estimate.thought this would prove useful for some people.i know there was a very old post on this,but this version is highly upgraded.


http://www.zealautowerks.com/horsepower.html

 

dyno charts would be a better estimate lol that thing is very simple

 

there used to be a website: pumaracing.co.uk that had a really good general calculation article on figuring potential HP so you would know what to expect at the dyno given your build plans. looks like the site is no longer up, but in doing some searching for the author's name (David Baker) seemed to pull up a few archived pages. It was a great read! the core of it was based on the total valve area (swept area) and then modified by some percentage if you've done mod A or mod B or mods A-Z.