Originally Posted by HTMtrSprt

Once again, it's time to dispell old myth from current fact..... as this quote from David Reher of Reher-Morrison racing engines attests - "Textbooks would lead you to believe that an exhaust to intake flow ratio of 80 percent is ideal - yet a typical Pro Stock head has exhaust ports that flow less than 60 percent of the intake runners." He goes on the say "You can improve the exhaust flow tremendously with about 40 minutes of work with a hand grinder - but the supposed improvements will just about kill the engine's on-track performance. I know because I've been there." And you know what.... he's dead right. After over 100 dyno pulls with 3 different 400+ cube LS engines, I can say without a doubt that there is NOTHING wrong with the exhaust ports on these heads. Take the L92 headed 427 which we dynoed, then pulled the heads and changed the valve seat angles from 45 degrees to 55 degrees (significantly hurting the flow numbers across the board) and then re-installed them on the motor and pulled it again.... the results: ZERO change in power and torque EVERYWHERE. So much for exhaust flowbench numbers meaning anything. And then there's the 454 we built w/ L92 heads and an LS7 intake manifold that makes 706 HP and 631 tq on pump gas w/ a hydraulic roller cam. Tried 3 different exhaust valve size and shape combos, didn't make any difference either. The intake port on the other hand was a different story....when ported to flow 360 cfm, in a configuration identical to everyone elses L92 heads, the motor wouldn't make more than 640 HP. After deciding to forget the flow bench and make the port LOOK right (this included a little TIG welding in the port and chamber, btw), the port LOST flow on the bench but miraculously gained 45 HP. Another item of note, the single plane manifold we tried made the same torque and hp as the LS7.... so much for the plastic manifold not making any power. The real limit on the L92 head is the valve length limiting the roof height at the guide and it is this that causes them to quit making power..... NOT the manifold or the exhaust port. The LS7 head has a valve that's about .350" longer it is because of this that we can make even more power with them over the L92/LS3's.

Originally Posted by Spinner

The fast is better then the ls7. It wasnt available at that time. Cost isnt even close. $$$ to epoxy weld and port