Car
Stock Torque
Torque / Liter
BMW 325i
181
72
BMW 328
207
74
Camaro V6*
225
59
944 S2
207
69
300zx
198
66
Supra
220
73
BMW 330
215
72
968
225
75
Mustang*
285
57
*Two valve motors have significantly less torque per liter displacement than four valve designs.
Somewhat surprisingly a plot of ITR class weight versus stock torque does not produce a linear relationship at all, The R² value for the regression model is less than 0.07 which reflects almost zero correlation. It would appear that a relatively subjective process was used when considering torque production in respect to classed ITR weight. Be that as it may, we would strongly suggest that a 1994/1995 Mustang GT receive a weight modification based on displacement of the engine and torque production. Figure 3 contains the ITR weight versus torque data.
Figure 3
It is believed that a stock 1994/1995 Mustang GT generally produces around 235 to 245 ft-lbs of rear wheel torque on a Dynojet dynometer. This will result in approximately 290 ft-lbs of rear wheel torque if one assumes a standard IT gain of 25%. In reality the gain is actually less than 25% with "street" IT-like builds producing in the neighborhood of 275-280 ft-lbs. The car is highly optimized for torque production from the factory due to small volume ports, high port velocity at low RPM, and small cam thus 25% improvements are hard to realize.
The point is that the 1994/1995 Mustang GT has torque capacity that is certainly within the performance envelope of ITR and should not be discounted because of class leading torque figures.
Other V8 Mustangs
The discussion thus far has focused on the 1994/1995 Mustang GT with a 5.0L OHV 2 valve per cylinder design. The car fits into the ITR framework quite well. However there are other V8 Pony cars that could fit into the class – earlier V8 Ford Mustangs and 3rd Generation GM V8 Camaros and Firebirds (3rd Gen F-Bodies).
The earlier Fox boded Mustang V8s, from 1982-1993, had a large variety of horsepower ratings due to changes in induction and cams over the years. The lowest horsepower model in this range is 165hp and the highest is 225hp. The cars are cheap and plentiful and, like the 1994/1995 Mustang GT, could be classed in ITR at approximately the same weight. But, none of these cars had rear disc brakes and each one would almost require a separate spec line in the GCR due to induction differences. For example the following is an incomplete list of horsepower and induction based on year:
Year
Horsepower
Induction
1982
165
2 bbl carb
1983-1984
175
4 bbl carb
1985
210
4bbl, roller cam
1986
200
EFI, Speed Density
1987
225
EFI, Speed Density
1988 (49 State)
225
EFI, Speed Density
1988 CA
225
EFI, Mass Air Flow
1989-1993
225
EFI Mass Air Flow
The cars would need to be specified at the same weight as the 1994/1995 V8 Mustangs, or, possibly at a higher weight. The 225 hp cars have better intakes and cams than the 1994/1995 V8 Mustangs and can produce slightly more power in IT trim.
If the cars were to be included we could simplify the years and models to the following:
Year
Induction
1989-1993 Mustang GT
EFI, MAF
This would provide the "best" Fox 3 ITR platform with the most power, torque, and strongest rear end. They have brakes that are inferior to the 1994/1995 cars, but they can produce more power than the 1994/1995 V8 Mustangs.