Last Hurrah

Having met our goal of running 9s while staying within our budget, we were itching to see how much quicker the car would go with some simple, long overdue mods. The goal this time around wasn’t to pick up tons of performance for the dollar, but rather to improve the consistency of the car. First off, Project Fox needed to shed some weight off the front end with a set of skinnies. The car’s oafish 15x7 front wheels and Mickey Thompson 26x10x15 Sportsmans worked great on the street, but just didn’t look right on a wheels-up drag car, as some very vocal readers pointed out. To address the situation, we ordered a set of 15x3.5 Billet Specialties RT front wheels paired with Mickey Thompson 26x4.5 ET Front tires. Out back, we bolted up a matching set of 15x10 RTs and wrapped them in some well-worn MT 28x10.5x15 ET Drag slicks. Likewise, since factory front brakes were a bit marginal for our application, we replaced them with a set of 11-inch Wilwood Dynalite drag brakes. Between the skinnies and the drag brakes, we knocked a solid 60 pounds off the front of the car.

Underhood, things got spiced up a tad as well. Since Project Fox has always battled inconsistent 60-foot times, we called up COMP Cams to see if the valve events could be tweaked to tailor the torque curve to better suit our application. As the techs at COMP explained, it’s very common for small-tire drag cars to run relatively wide lobe-separation angles to move the torque peak higher up in the rpm range. This eases the hit to the tires coming out of the hole while tacking on a few more ponies up top. Whereas Project Fox’s original cam was ground on a 109-degree lobe separation, COMP spec’d out a new one at 114 degrees. Furthermore, the new stick measured 278/290 degrees of duration at .050 versus the original’s 273/278 degrees at .050, again to soften the low and midrange torque. On SAM’s dyno, the numbers played out just like COMP predicted. From 3,500 to 4,000 rpm, the new cam was down an average of 50 lb-ft of torque, but the horsepower peak was now at 6,700 rpm instead of 6,500. Overall, the new cam produced 11 more peak horsepower than the old one, but more importantly, it blew the old one away at 6,800 rpm, at which point it was making 39 more horsepower.

To put it all to the test, and for one last hurrah down the track, we headed back to San Antonio Raceway. Airing the slicks down to 13.5 psi and leaving at 3,500 rpm off the transbrake netted an all-time best of 9.81 at 141 mph on a 1.40-second 60-foot time. On the next pass, we increased the launch rpm to 4,000, which netted a quicker 1.38-second 60-foot, but a slower overall pass of 9.84 at 140 mph. Although the car only picked up slightly more than a tenth—which is by no means insignificant at this power level—the car’s consistency was substantially improved. Unlike with the radials, which required constantly changing the MSD’s launch retard curve depending on track conditions, the slicks allowed leaving off the ’brake with full timing advance every single time. Moreover, the Mustang pulls 60-foot times in a 1.38- to 1.44-second range all night long, and consistent 9.80s pass after pass. Like we said up top, mission accomplished!

Props

Even if this next bit sounds like an infomercial, we don’t care. We’ve been beating on Project Fox like a dissident in a Cold War prison camp, logging 100-plus passes over the last year, but it refuses to break parts. That’s a testament to the premium quality components that went into the build, as nothing tests the performance and durability of aftermarket parts like an inclement track environment.