There’s long been a debate over whether a Fox throttle body conversion on a ’94-’95 Mustang GT or Cobra makes power. Many have said Fox Mustangs have better throttle response compared to their SN-95 pushrod brethren. Having driven both, I can attest to that assumption. Whether its throttle response or the SN-95 Mustang’s increased weight over a Fox are both hard to tell, and measure. This is something we plan to investigate and cover with my ’94 Cobra, but until then our friend Paul Riva has given us some useful dyno numbers to help clear up this controversy…or has he made it even muddier?
We featured Paul’s ’95 GT in the December 2004 issue, and were quite impressed with not only the car, but also the extensive notes Paul had taken while building the car. Paul’s GT is a little different than when we featured it both mechanically and aesthetically. Though we think it looks better now than it did before we’re concentrating on the mechanical improvements this time around.
Nowadays Paul’s GT boasts a 331 stroker based on a Dart block, and using Scat and JE/SRP bottom end components. We won’t hold this against Paul, but Ed Curtis from Flowtech Induction had his paws all over the 331’s valve train, including the camshaft. Up top is a pair of AFR 165cc heads with a Holley SysteMAX intake. You can read all about Paul’s car at his site www.angelfire.com/pa2/killercanary/. He too had always wondered if the Fox throttle body conversion would result in increased power so he tried it, and here are the results.
These results are somewhat clouded since Paul utilized a 65mm throttle body with his ’94-’95 set-up, and 75mm throttle body with the Fox conversion. If you maximize the above dyno sheet you’ll be able to see the improvement Paul gained from the Fox body throttle body conversion. His combo picked up 9 horsepower and 5 ft/lbs of torque with the conversion. Paul wants to make 400hp to the wheels with the AFR 165cc heads; something he says has not been done in naturally aspirated form. He’ll be adding long tube headers, a Dr. Gas X-style crossover, 30 lb/hr injectors, and porting the Holley SysteMAX intake.
To really get to the bottom of this Fox body throttle body conversion we need to compare apples to apples with the same size throttle body between the two set-ups. That way, we’ll know for sure if this conversion is worth it. Add that to our list of stories to do.