I've seen some reverse split duration cams (ie. 230 intake/224 exhuast) advertised for LS1's and VTEC's and wondered why the reverse split? Obviously these are some good flowing heads from the factory. I know that in years past the exhaust ports in heads have needed help and given longer duration than the intake. And I know that heads like AFR work well with single pattern cams like the LPE 219/219. Why then the reverse split? Does the exhuast "side" of the head just flow so well that it actually requires less duration? Is there some inefficiency in the intake track or side of the head? Just curious.

 

Right, it often has to do with the relative flow of the 2 sides of the heads; also, you can move the power band up and down, or flatten or peak the torque curve, by doing that.

 

You can move the power band up and down? And flatten and peak? I am sure you know what you are talking about, just the manner in which you presented it confuses me. Clarification?