Business Up Front, Party Out Back: Speed Academy’s Mullet Mustang
Text and photos by Dave Pratte
Sometimes you need to step outside your comfort zone and do something a little different. For Pete and I, the brains (and looks) behind Speed Academy, a YouTube channel and website dedicated to building fast cars and having fun doing it, we’ve primarily been Japanese and Euro car enthusiasts.
Okay, so I did own a Fox body Mustang GT for about three weeks before my dad decided to do some pre-meme winter driving, and stuffed it into a guardrail after hitting a patch of black ice. I paid $6,500 for that car, but the insurance company paid me $9,500 for it. A sum I promptly used to buy an Eagle Talon TSi, which was so advanced at the time that it turned me into a lifelong JDM fanboy.
Long story short, Pete and I decided it was time to expand our horizons by dabbling in the dark arts of Detroit steel. We set about acquiring an S197-chassis Ford Mustang GT. We wanted to get into something for under $10K, so although it was tempting to step up to a late model S197 for its 412 hp 5.0-liter Coyote V8, our budget dictated we’d instead be playing with the significantly less sophisticated 3-valve, 4.6-liter modular V8 rated at a more modest 305 hp.
Because we like a challenge (and are suckers for punishment), we ended up buying the least expensive unmodified Mustang GT we could find, this 2005 beauty in Satin Silver Metallic with Crimson Red leather interior. The nickname “The Mullet Mustang” seemed fitting, given that its 4.6-liter business end seemed to be running smoothly, while the party end had all the usual quirks of a solid rear axle (you know, stuff like axle hop and a general sense of impending doom if you take a corner above the posted speed limit).
Ok, so we had a bit of an unplanned repair to make to the timing system, which we used as an excuse to upgrade to Ford Racing phasers and oil pump along with an Edelbrock water pump, but after this lesson in high-mileage car shopping, we felt like we had a solid starting point for a fun and affordable track car build that would make cool V8 pony car noises.
As is our standard procedure, we like to baseline every car we build in stock condition before we start the upgrades. However, since the stock brakes were totally shot, we decided to upgrade them to DBA 4000-series T3 rotors and Hawk Performance DTC-50 racing brake pads before heading to our local race track, Toronto Motorsports Park, to set a lap time around the eleven-turn road course and down the NHRA spec drag strip.
The brakes worked great, which meant we didn’t die, but the worn out Pirelli all-season tires and twelve-year-old suspension meant there just wasn’t much grip to work with. Without some serious upgrades, we had a legitimate meme-maker on our hands, and a slow one at that. With a best lap time of 1:31, and a quarter-mile time of 14.87-seconds at 98 mph, we had a lot of work to do to beat our targets of 13.0-seconds in the quarter-mile and 1:21.4 around the road course—a lap time I set in the track-focused version of the S197, a stock Boss 302.
Normally we’d start by upgrading the wheels, tires, and suspension, since that’s where the biggest gains typically come from at the race track—not to mention the improved appearance. However, since this was our first V8 car in quite some time, we started the build with a set of Borla long tube headers and axle-back exhaust, along with a K&N FIPK2 intake system.
This paid immediate dividends in the hairy-chested soundtrack department, and as we found out with the help of OnPoint Dyno, it also paid off with a serious bump in power. Thanks to a custom tune by Sasha from OnPoint using a SCT Performance X4 programmer, the power jumped from a baseline of 250whp and 274wtq, to a very impressive 302whp and 331wtq.
From there we circled back and got to work on the grip part of the build, starting with an ultra-sexy set of 18×9.5-inch Enkei GTC01RR wheels along with a surprisingly sticky set of Kumho PS91 tires in a 275/35R18 size at all four corners. We also pulled off the stock shocks, springs, and swaybars, and replaced them with the good stuff from Eibach including Multi-Pro R1 coilovers and adjustable front and rear swaybars.
The difference the added power, and this first round of grip upgrades, made at the track was remarkable. Our best lap time dropped by an amazing seven seconds, from a 1:31.0 down to a 1:24.0. More importantly, the Mullet was now an absolute blast to rip around the road course, as it put the power down coming out of corners with a confidence-inspiring composure I simply didn’t expect from a live rear axle car. The handling balance was also spot on, thanks to the Eibach goodies, with no understeer in sight and easily induced rotation with the throttle. Honestly, we could have shut the build down right here and I would have been 100% satisfied.
Pete was less satisfied, however, since he was our designated drag racer for the build and the Mullet’s quarter-mile time only dropped two tenths of a second, to a 14.68-second pass at 99 mph. Apparently, a stiff road racing oriented suspension on a street tire isn’t ideal for the drag strip—who knew? We learned some good stuff here, though, like the fact that the Mustang desperately needed a higher final drive ratio in the rear end for better gearing down the strip, plus the limited slip differential was feeling pretty worn out.
From here we attacked the rear end, rebuilding the differential with Ford Racing carbon clutch discs and 4.10 ring and pinion, in place of the weak sauce 3.55 rear gears. We’d never rebuilt a rear end before, so we learned some lessons about shimming and setting the runout that was fun. Although, also a little painful since we had some gear whine initially, which required us opening up the rear housing a second time to get it right.
We also decided to up the rear grip level further with a Watts link kit from Whiteline, along with their adjustable lower rear control arms, and pinion angle adjustable upper rear mount. If you’re unfamiliar with how a Watts link works, it replaces the single panhard bar with two equal length arms that mount to the custom differential cover. This greatly stabilizes the rear axle and gives it a consistent roll center, all of which translates to improved rear grip. We also tossed in a set of roll center adjusting front lower ball joints from Whiteline, along with some of their front bushings.
After that we headed back to Toronto Motorsport Park, where, in unseasonably cold temperatures, I managed to improve the Mullet’s best lap time by a further 1.4 seconds, to a 1:22.6. The Watts link rear end let me get on the power much earlier coming out of corners without any unwanted rear end instability. Better yet, Pete shaved a solid half-second off his best quarter-mile time, bringing it down to a 14.1 at a 102 mph. Clearly, the 4.10 gears are a solid upgrade for the drag strip, but we were still a long way from our goal of a 12.99.
At this point we probably should have thrown a supercharger under the hood and taken the easy power gains that come with it. Instead, we decided to travel the more challenging road of trying to find more naturally aspirated power, which might sound simple enough when you’re working with 4.6 liters of displacement, but the old three-valve heads on these engines just don’t like to flow much air.
Still, the Stage 2 XFI VSR Comp Cams camshafts and valvetrain we decided to install did pick up some solid power. From 4,400 rpm right to the 7,400 rpm fuel cutoff, these camshafts delivered big gains, with peak power rising to 329 whp. We did lose some power and torque below 4,400 rpm, though, so there is a trade-off when going to these cams. For a track car build like ours, we were happy to trade the bottom end grunt (which this engine already had a lot of) for some top end jam (which this engine sorely lacked prior to the cam install).
Since it was winter now, we turned our attention to some interior mods, including Auto Meter AirDrive Wi-Fi gauges and dash gauge pod, Momo Super Cup seats with Planted seat rails, and a Momo Prototipo steering wheel. We also installed a Mishimoto radiator and oil cooler, since we felt the engine was getting heat soaked the last few times we track tested it (more on that later).
While we waited for the snow to melt we also installed a Roush short shifter and a QA1 carbon fiber driveshaft. The Roush shifter took all the slop out of the system and delivered nice short throws with a satisfyingly mechanical feel to them. Along with that, the carbon driveshaft shaves an impressive 19 pounds of rotating mass, and got rid of a very annoying vibration the drivetrain had at cruising speeds. Oh, and we also bolted up an MMR front lip to give the Mullet a country-strong chin. It came unpainted, so we handed it over to Luke at 242 Customs, who did such a good job on the paintwork it was almost too good for our high-mileage pony.
With the snow gone, we headed back to the track and failed to go any faster. In the immortal words of Billy Bob Shakespeare, “WTF, dude!” The lack of improved pace, both around the road course and down the drag strip, seemed to stem from the fact that the engine was getting very hot. If it was heat soaking last year, with the more aggressive cams and tune, it was heat soaking even worse now.
We were seriously tempted to just throw in the towel at this point, but instead we decided to try some ghetto cooling mods, including pulling the restrictive grille out and ducting fresh air to the radiator and oil cooler with some duct tape reinforced cardboard diversion panels. Hey, we called this thing the Mullet for a reason, and it wasn’t because we were promising to keep it classy.
Despite the A/C condenser being a plugged up mess that was severely restricting airflow to the radiator, our ghetto cooling mods worked surprisingly well, allowing me to rip a solid five hot laps without any signs of the engine heat soaking, or the ECU pulling timing. The bad news is, I came up one tenth of a second short. I got the Mullet’s lap time down to a 1:21.5, but I couldn’t find a way to squeeze out that last tenth or two to beat the 1:21.4 I did in the 2012 Boss 302. Still, for a tired old 4.6-liter GT, and about $20,000 of high-quality goodies bolted to it, we basically matched the $43,000 Boss 302 and its 444 hp Coyote V8. With a wider set of wheels and tires on the Mullet, say 295s or even 305s all around, I’m confident it would go at least one or two seconds a lap faster.
Over on the drag strip we learned a couple of things. For starters, we found out that our AiM Solo lap timer was extremely accurate around the road course but surprisingly inaccurate down the drag strip. Running the Mullet during a Test & Tune night at TMP, we found the AiM was reading about three to four tenths of a second slow, with Pete’s best run of the night showing a 14.1 on the AiM, but a 13.7 at 109 mph on the official NHRA timing system.
The other thing we learned is that a road race setup simply doesn’t work well on the drag strip. I know, we should have learned this much earlier and made some adjustments, but I guess at the end of the day if we had to choose between a fast car around the road course, or a fast car down the drag strip, we’d opt for the road course setup because we love corners and threshold braking just as much as we love stomping on the gas pedal and banging gears.
So maybe that’s the third thing we learned from this build: that at our core we’re road race guys who enjoy the challenge of setting up a well-rounded car that can perform on the street and around a race track. But we still had a ton of fun building the Mullet and learning the hard way that drag racing takes real setup skill and a totally different approach than a road race car. Someday we’ll do a dedicated drag car build, but for now we’re satisfied with the lessons learned and the fun had with our S197-chassis “Mullet” Mustang GT.
Special thanks to Turn 14 Distribution, whose support as the presenting sponsor on the Mullet Mustang’s build made the project possible, and also gave us the perfect excuse to drive it down to the Philadelphia area for their inaugural Open House & Car Meet at their new warehouse facility. We had a blast on this trip and are looking forward to bringing our next build to Turn 14 Distribution’s 2018 Open House.