Track Validation

As of our last report in the Mar. ’11 issue, Project Fox clicked off a series of 10.0-second passes at Lonestar Motorsports Park in Sealy. Launching off the footbrake, the car ran a best of 10.01 at 137.89 mph on a 1.47-second 60-foot time. One freakishly good launch notwithstanding, the 60-foot times had stagnated in the 1.50- to 1.59-second range, so the next logical step was installing a TCI transbrake. Unfortunately, during our next trip to the track, the 275/60-15 Mickey Thompson ET Street radials couldn’t handle the additional shock placed upon them by the transbrake, sending them into violent tire shake. Stiffening up the rear shocks and increasing tire pressure helped the situation, but the best pass of the night was a disappointing 10.21 at 137.49 mph on a 1.67-second 60-foot time.

Shortly thereafter, the local tracks went into a brief reprieve for the winter holiday season. That wasn’t a bad thing, since an improperly shimmed starter had ripped the teeth off of the Mustang’s flexplate, and it gave us time to pull the trans and patch everything back up. Once back on the road, the next couple of test sessions revealed an ugly truth about the drawbacks of running radials instead of slicks. While the radials work great under ideal track conditions, they proved to be extremely finicky and unforgiving in cold weather. Once the ambient air temperature dropped into the 30s, they refused to hook regardless of changes in suspension tuning. Pulling timing coming out of the hole with the programmable MSD 6AL-2 ignition box didn’t help, either.

Consequently, we sat things out for the rest of the winter. Unfortunately, Mother Nature decided to skip spring altogether and jump straight to summer. This wasn’t just any summer, but the hottest summer in Central Texas history, with 90 days in which the temps topped 100 degrees or more. We reasoned that any potential improvements in 60-foot times would be offset by a big hit in horsepower, so we patiently awaited some cooler fall air. Call us pansies, but the prospect of roasting in a black fire suit in the staging lanes wasn’t very appealing, either.

Once September rolled around, the daytime temps were finally back down into the 80s, so we headed back out to San Antonio Raceway. In an effort to eliminate the tire shake that had plagued our prior runs off of the transbrake, chassis man Bill Buck made changes to the Mustang’s instant center. By relocating the rear of the lower control arms upward, and thereby moving the instant center closer to the front of the car, the goal was to reduce the rate of weight transfer to the rear tires, and keep them loaded up longer after launch. Fortunately, it worked. After popping the transbrake at 3,500 rpm, Project Fox ripped off a 9.95-second pass on a 1.42-second 60-foot time. The car decided to pull left at the far end of the track, which forced us to lift right before the finish line, but it still coasted to a single-digit pass with a 130.55 mph trap speed. Finally, after a year’s worth of testing and tuning, we had ourselves a street legal, naturally aspirated, pump-gas–friendly, full-interior car that runs 9s on a stock-style suspension for under $25,000.