First let me start off by saying that the ATI and Vortech units are very good blowers.
Now, as far as the Vortech's being some of the fastest all the time - well, I beg to differ. In different race classes there are certain blowers that dominate (or in some cases, turbos or nitrous oxide), but all in all the Vortech and ATI Stangs run about the same. One race the ATI wins, the next it's the Vortech.
Just as an example, Bennett Racing (from somewhere in Alabama) has a couple ProCharged Stangs running in the 7's @ ~ 180 mph - pretty damn quick if you ask me. And then there is the Renegade class which was full of ATI blown Stangs that won a ton of races this past season. Additionally, this past season, Les Baer (another top Mustang drag racer) switched to a ProCharger D3M blower.
Overall, success really depends upon so many things - engine combination, cam selection, suspension setup, gearing, transmission, the list goes on and on. The fact is that ATI and Vortech make some extremely powerful superchargers that are capable of producing HP levels into the 1600 HP range - given a properly built engine of course.
So, to wrap up, ATI and Vortech are probably just about equal in efficiency, but remember that it is not always the guy with the most CFM or psi that wins (although it never hurts!
)
E
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1991 5.0 LX Coupe -37,800 miles
13.17 @ 106.14 mph w/ 2.138 60'
Pro-Charger D-1SC on the way!!!