If turning left and right on a road course wasn't unusual enough, Part 3 of our budget road race project deviates even more radically from the typical Muscle Mustangs & Fast Fords street/strip project car. For this project we're running as close to a bone-stock 5.0L as you are likely to ever see in the pages of this magazine. But since the Camaro-Mustang Challenge rules limit rear-wheel output to a maximum of 230 hp and 300 lb-ft of torque, we just didn't need to get very tricky with the engine.
Despite the '87-'93 5.0L H.O. engine's nominal factory flywheel power ratings of 225 hp and 300 lb-ft, it's possible to come very close to those numbers at the rear wheels with very slight modifications. Virtually everything in, or on, our engine is stock, from the oil pan to the intake manifold, including the 1991 H.O. roller camshaft, the E7TE iron cylinder heads, the stock tubular exhaust manifolds, the stock SN-95-style upper intake manifold, MAF sensor and throttle body, and even the stock airbox and filter. The only significant deviations from factory equipment are an underdrive crankshaft pulley, a BBK off-road cross-pipe with open-exhaust tailpipes, and the conversion to a Fox-style A9L engine computer with a Painless Performance wiring harness.
We did this to eliminate the SN-95's funky fuel and spark timing maps, since the CMC rules prevent using any aftermarket chips or tuners to reprogram the computer. As a result, we're stuck with the notorious rolling idle from the mismatch of the SN-95's 60 mm throttle body and larger 70 mm MAF sensor with the Fox computer, but the combination runs at a very happy 12.5:1 air/fuel ratio at WOT, just a tad on the rich side, which isn't a bad thing for this application.
On C&M Performance's Dynojet chassis dyno in Hubertus, Wisconsin, we made 225 hp and 294 lb-ft of torque from this combination, just a hair under the maximums allowed, and very robust numbers for such a stock 5.0L. We attribute the healthy gains primarily to the abbreviated accessory drive system, removal of all smog equipment, and open exhaust system from the stock headers back.
Ultimately, this will give us plenty of power to get off the corners, plus the reliability to go a season or more without a rebuild. Also of importance is having a proper transmission and rear, so we'll tackle that in Part 3 of our CMC build.
After hosing off a few seasons...
After hosing off a few seasons worth of oil and grime, we dropped the engine and trans directly back into the new chassis. We even carried over the accessory brackets, engine harness and computer, cross-pipe, and tailpipes from the Fox. The only changes from the previous installation were to swap the Fox-style upper intake manifold and air inlet tract for SN-95 parts that fit the new chassis better, along with SN-95 exhaust headers with the provision for the external EGR. We also converted to an SN-95 3G alternator.
The sum total of engine building...
The sum total of engine building we did for this project consisted of pulling the motor and trans out of one car and dropping it into another. The 5.0L is about as basic as it gets: Ford Racing replacement short-block, junkyard E7 heads with a cheap valve job, H.O. roller cam, stock intake and exhaust manifolds, and abbreviated accessory drive with an underdrive crank pulley.
We made very few changes to...
We made very few changes to the basic engine combination we've been running for a few years, but needed to get a new dyno certification for the car and wanted to verify what effect the new intake parts had on overall power. For that we headed to C&M Performance in Hubertus, Wisconsin, where owner Marv Zuidema made three pulls on his Dynojet 248.
Average result: 225 hp at...
Average result: 225 hp at 4,800 rpm, and 294 lb-ft at 3,500 rpm, the identical horsepower and a bump of 4 lb-ft from the other car.
We upgraded our T-5's overdrive...
We upgraded our T-5's overdrive ratio with Astro Performance's A-5 0.79 Fifth Gear kit, which replaces the stock gears splined onto the main and countershafts. Note the thicker gear teeth and shallower helical angle on the Astro gears compared to the stock overdrive gears, which greatly increases the strength of the gears and reduces the side thrust against the transmission case. Replacing the Fifth gearset is a simple swap that you can do without opening up the main case or using any special tools beyond a pair of snap-ring pliers. We actually did it in about an hour at the track using the bed of a pickup truck as a bench.
No matter what method you...
No matter what method you use to establish the pinion depth in the rear, the best way to verify it is to examine the resulting gear mesh pattern with marking compound. We messed this up the first time by slathering too much marking compound onto the gears, which made it impossible to discern a clear pattern. So apply the compound sparingly to two or three sets of teeth and rotate the gears a few dozen times until a light pattern is transferred onto the gear teeth. Then consult a gear pattern chart to assess it. The pinion gear teeth should mesh with the ring gear in approximately the center of the teeth, both horizontally and vertically, to ensure sufficient engagement and quiet operation on deceleration. We incredibly got the pattern dead nuts on the first shot.