[MAP]

Greetings,

For my 383 small-block Chevy re-design effort, I compared three highly disparate sources: first and foremost, the consultation advice of Mr. Vizard himself, then Engine Analyzer Pro, and then this CompCams software that you can download as freeware.

The goal metrics were: peak torque; peak hp, torque bandwidth between low-rpm limit of 80% peak torque, and high-rpm limit of 80% peak torque (the difference between the two, divided by the high-rpm limit, is what I call the torque bandwidth ratio. I usually strive for 0.75 or better for a "daily driver" street motor, where economy and performance are both important.)

I expected large differences between the three, and to quantify what I mean by "large," I mean optimized camshafts differing by more than about 8 degrees in 0.050" lift duration, and by more than a few degrees in LSA's.

Amazingly, at least for me, the differences were moderate or small according to the above criteria, with a maximum difference across the set of 5% for predicted HP and torque.

Nevertheless, close agreement between three sources in one isolated instance does not a rigorous comparison make, so do take caution.

Having said that, of course I put my highest confidence in Mr. Vizard's recommendations, since his opinions are finely nuanced, and based on considerations of all kinds of minutiae which no FEA or CAD package I've ever seen even has inputs for!

Best,
Mark