Muscle Mustangs & Fast Fords
Fox-Body Wheel & Tire Combo - Finding The Weakest Link
We find 139 rwhp and break a transmission in the process.
Over the past year or so, we’ve taken a nearly forgotten project and revived it with a late-model powerplant and a completely reconfigured suspension. The realization that the car was finally running and driving again acted as blinders when the car’s six-year hibernation came to an end earlier this year. Hearing the engine come to life and backing the car out of the shop for the first time was so exciting, it didn’t seem to bother anyone that there was something mechanically wrong and the car only made 212 rwhp.
Looking back, the 13.92-second timeslip at 97 mph and 1.80-second 60-foot time with 212 hp isn’t bad for what it is. After taking the car out on the town a few times, a little bit of the magic has worn off (ok—a lot), and it’s time to find out why it’s not making power. Our first thoughts were the open exhaust was tripping the knock sensors and the computer was pulling timing, or the IMRCs were not opening.
Before we get to its power issues, the rolling stock is something we’ve gone back and forth over. Drag race-only wheels? Street wheels? Big ’n’ littles? The options are so vast, it was difficult to decide.
Your author has owned many Fox-bodies over the years, and many of them, including this car, have had ’98 Cobra wheels. Wanting to do something different and unique, we contacted Weldcraft Wheels in Livonia, Michigan. The company specializes in widening and narrowing wheels for custom fitments. After some measuring and emails back and forth, we decided to widen the rear wheels by 1 inch and narrow the fronts by 3.
When the wheels came back, we were impressed with the final result. The welds were impressive to say the least, and Weldcraft guarantees the wheels to balance with no issues.
Next were tires. For this we contacted Coker Tires for a set of M&H Racemaster drag radials. The radials measure 185/55R17 up front and 275/50R17 in the rear. With the rolling stock in place, the MM&FF staff, along with the help of some other editors, adjusted the coilovers and adjustable rear control arms to get the ride just right.
Next, we shifted our attention to power. The first order of business was fabricating an exhaust system. With all of the added suspension components attached to the rearend, tailpipe room is reduced. Although the suspension kit is design to work with tailpipes, routing the exhaust wasn’t something we were really worried about. After rummaging through the shop, we were able to come up with enough tubing and a complete X-style mid-pipe to fabricate the entire system. With some stainless tubing and a set of Magnapack bullet-style mufflers from Magnaflow, we assembled our exhaust.
Knowing there was a good chance the IMRCs weren’t opening, we opted to simply remove them and take them out of the equation. We called Steeda Autosports for a set of its Charge Motion Delete Plugs for the ’09-’10 Three-Valve intake. The billet aluminum plugs are simple to install, and after about a half hour, we were ready to retest the car.
Chris Jones from Blow-By Racing modified the calibration for the deleted IMRCs, and emailed us the file. After loading the tune into the ECM via our SCT Xcal3 handheld tuner, we took the car for a short ride. In a word—wow! It was a whole new car. After a short drive around MM&FF headquarters, we were ready to strap the car back on our Dynojet chassis dyno to see how much power we picked up.
As word spread around the office that we were getting ready to re-dyno our Three-Valve Fox, much of the SIM editorial staff poked their heads into the Snap-on Tech Center to find out our results. While everyone was waiting, bets were made on how much power it would lay down. We rowed through the gears, finally stopping in Fourth before laying into the loud pedal.
When the tach reached 7,000 rpm and the run was over, were pleasantly surprised to see 351 rwhp and 337 lb-ft of torque. The addition of the Steeda Charge Motion Delete Plugs, Blow-By Racing tune, and exhaust system netted us a gain of 139 rwhp and 49 lb-ft of torque at the respective peaks. Throughout the curve, gains were as high as 150 hp and 125 lb-ft of torque.
When we finally made it back to the track, we were looking for big performance improvements. We spun up the M&H Racemasters and inched to the line. When the light went green, your author let out the clutch at a mild 2,800 rpm, which netted a 1.65- second 60-foot time. When we shifted into Third, our T45 began showing its age, and wouldn’t allow for any type of quick shifting. After hitting the gate twice, we finally found the gear, and ended the run with a 12.63- second timeslip at 108 mph.
Knowing this would have been a low-12-second pass, possibly in the high-11s with a more aggressive launch and clean shifts, we headed back out. Unfortunately we met the same fate and our run was ended early. Our third attempt, however, ended our night early. A hard launch netted us the best 60-foot time of the night (1.62 seconds), but the shift into Third was all the T45 could take, and after a loud BANG, it was time to limp the car home.