Over the last several years, South Florida resident Eric Leeper has been dabbling in the X275 class and other similar race venues, most recently in his second-generation Ford Lightning, powered by a 5.4-liter Ford Modular engine assisted by a turbocharger. But when the realization set in that the Lightning was severely overweight for these classes, and the desire to show what he and his team were truly capable of became a priority, Leeper decided it was time to make a change. Driven by the need to be truly different in a sea of Fox Mustangs, he looked back into the past and picked up a 1966 Mustang.

“I sold the Lightning as a roller, kept the drivetrain, and pieces and parts from that vehicle made their way to this one. I kept the engine, transmission, Racepak, center section, all that good stuff. The transmission didn’t make the swap; that’s sitting in my garage as wasted money, but I was able to at least salvage the carbon-fiber driveshaft,” Leeper says with a laugh.


The car, as seen here, is a Fastback model – but it didn’t begin life that way.

“It is different. The truck got a lot of cool responses, but it was really hard to run with the pack – it was 300 to 400 pounds overweight. I came across this car as a roller. It was a project car that got way beyond what the guy was able to complete. He took it all apart and realized that he was never going to be able to get it back together. Oddly enough, when I bought it, it was a Mustang coupe,” Leeper says.

The car as purchased, with Zach Leeper laying claim to a future driving job.

The car as purchased, with Zach Leeper laying claim to a future driving job. (Eric Leeper photo)


Turning Steel Into Gold

This was not an overnight build; Leeper is a general contractor who is insanely busy at his day job. From the very beginning of the project, when he commissioned Greg Zoetmulder of GregZ Designs to develop a rendering of the end result, it was a process that included hundreds of late nights and thousands of hours to complete from start to finish. Total build time was about three years, and Leeper never lost sight of the finish line throughout the ordeal. Instead, when the going got tough, he’d focus on the rendering and manage to pull through to the next stage of the build.

The original rendering by GregZ Designs.

The original rendering by GregZ Designs.

With the help of longtime friends Azim Moonab and Chris Crown of AC Carcraft in Coral Springs, Florida, Leeper was able to achieve the dream of owning that Fastback. Through the use of solid engineering techniques and a well-thought-out build plan, the chassis became the answer he sought when the project began.

“The car is all stock dimensions – it’s all stock steel except the front end. Other than the front spoiler, you could fit a NASCAR template on this car if they had one for a 1966 Mustang. Other than the front spoiler, it’s dimensioned just right.”

Coupe turned Fastback? The process for turning one into the other wasn’t nearly as difficult as you might imagine.

Mid-process for the coupe-to-fastback conversion.

Mid-process for the coupe-to-fastback conversion. (Eric Leeper photo)

“Dynacorn sells the quarter panels, the piece between the trunk and the rear window, and the roof skin. I was looking for a Fastback, but rotted-out piles of junk were eight to 12 grand,” he says. “But after doing some research, I found out that all three body styles are exactly the same from the door jamb and rocker and the fender line on the quarter-panel down and across the taillights. It’s only that sheetmetal between the convertible, the coupe, and the Fastback that’s different.”


Since the Mustang was going to be a racer, they were able to basically build the Fastback structure around the cage and rear suspension, forgoing all of the other sheetmetal which would be necessary for a street car.


“All of the underlying structure is different, but for a racecar, you go in there and cut and grind all of the stuff out that you don’t need anyway. We drilled the spotwelds at the taillight panel, all the way along the rocker panel to the door and up around the door. We had to just drill like a thousand spotwelds out, but the only part we had to cut was the top of the window post. That was fairly easy. You could see right where the seam was from the roof to the pillars. Once it was all cut off and we had the new panels, we built a Fastback. It was a pretty cool process,” Leeper says.

front end

Stock dimensions - sort of. Just a little long on the back side. The AC Carcraft team tuned it up to fit properly. (Eric Leeper photo)

One major struggle reared its ugly head when it came time to find the one-piece front end for the car. A call to one manufacturer where Leeper was told the finished product would be exactly what he needed, turned into a monstrous project – and then wasn’t even close to what he had asked for when he picked up the part from the manufacturer after months of construction. Luckily, it was correct to the rear of the front wheel arches, and the AC Carcraft team was able to salvage the project by trimming down the rear to make it fit properly. Fortunately, the fiberglass doors and hood from VFN and the dashboard and decklid from Glasstek didn’t present the same issues.


And then came the trip to paint jail. Anyone who’s ever tried to have a racecar painted knows the struggle of paint jail. It can often derail even the best-laid plans when the painter doesn’t come through. Leeper trucked the body all over South Florida, pulling the car out of multiple shops who couldn’t meet his deadlines before finally landing at T-1 Autobody in Miami. There, the Deep Impact Blue hue was laid on the car’s flanks before the graphics were placed by Mike Stavrinos of Speed & Truck World.


Once all of the chassis details were buttoned up, the AC Carcraft-built chassis carried a ladder bar rear suspension legal for use in X275, NMRA Street Outlaw, and Pro 275; basically, wherever and whenever Leeper can make time to race, the car fits in with a simple weight and turbo change.


Turning Fire Into Performance

There are few Modular-style engines running in the upper echelon of X275 and Street Outlaw; in fact, Ronnie Diaz is the only racer with a true Modular engine, and John Urist’s new Coyote-powered 2015 Mustang is the other notable entry. Leeper, who has worked closely with Tim Eichhorn at MPR Racing Engines in Boynton Beach, Florida, is planning on being the third racer to make noise with one of these overhead camshaft wonders.


This particular bullet is based around the 5.4-liter aluminum Ford GT block, which has been filled with a billet Callies crankshaft, GRP aluminum connecting rods, and Diamond pistons. Kris Starnes Racing chipped in to design the fully-massaged Navigator four-valve cylinder heads; they’re treated to Ferrea valves and PAC racing springs, while Bullet Racing Cams’ custom-grind camshafts sit on top. Depending upon which class he’s racing, either a 94 mm Gen II Pro Mod or 85 mm Gen II Pro Mod Precision Turbo snail feeds the Marcella Manifolds sheetmetal-billet intake concoction through a Chiseled Performance intercooler system.


This car still runs on gas, mainly because the NMRA doesn’t allow alcohol fuel, so creative plumbing techniques were utilized during the car’s creation to maximize space. The engine bay of the ’66 isn’t exactly overflowing with extra space, so the Race Parts Solutions-sourced tubing was run underneath the manifold into the car, through the intercooler, then back into the manifold. On the exhaust side of the cylinder heads, Chris Crown fabricated what must be the absolute coolest headers on any car in the class – they hug the block and run flat underneath the super-shallow Dailey Engineering dry sump system, then turn forward, merge four-into-one on each side, then the collectors merge again prior to the single massive pipe into the turbocharger.

These headers are SLICK! (Eric Leeper photo)

These headers are SLICK! (Eric Leeper photo)


Every piece of tubing, and every surface in the car, has been either powdercoated, painted, or treated to Jet Hot for its heat dissipation capabilities. The fuel system is anchored by a Weldon Racing 2345 pump, and lines, fittings, and filters from Race Part Solutions. Leeper and RPS’ owner John Kerr go way back, and Kerr has always been a big part of Leeper’s racing efforts; it’s no different with the creation of this car.

The engine is controlled by one of FuelTech’s FT500 engine management systems and the company’s coil-on-plug ignition system. Leeper credits Luis DeLeon from FuelTech for teaching the team the finer points of making the system work.


“Luis DeLeon from FuelTech has been outstanding with our conversion to the FT500. He has made sure we not only got the car tuned properly but continues to support and teach us the system. Their support is remarkable,” he says.

Leeper picked out the best of the best parts to go into the driveline. Dave Klaput at Proformance Racing Transmissions put together the Turbo 400 three-speed transmission with a PTC billet bolt-together torque converter. The power runs through a carbon-fiber driveshaft into a Sheffield Enterprises fabricated 9-inch floater-style rearend equipped with Strange Engineering gun-drilled 40-spline axles and a Strange Ultra case filled with 3.90 gears and spool.


AC Carcraft designed and built a set of custom front A-arms, while Leeper picked out Santhuff front struts and Penske double-adjustable rear shocks, which have been subjected to the black magic treatment from shock guru Mark Menscer of Menscer Motorsports. Weld Racing V-Series spindle-mount front wheels and double-beadlock rear wheels were custom-coated by James at Mr. Speed Coatings and roll on Mickey Thompson 275/60/15 ET Street Radial Pro rear tires and 26×4 front-runner tires.


So it looks good, but how does it run? Dragzine shot these photos on the car’s very first real outing at No Mercy 7 in South Georgia; Leeper says the team was sorting out some unexpected issues and weren’t able to make any clean runs throughout the course of the weekend.


“It was a rough go. I figured we’d be chasing a lot of gremlins and not setting the world on fire at the first event. We finally figured out the transmission’s behavior just before the first round. I got lucky in round one but in round two I had Phil Hines, who was running great all weekend. We came out, went off the trailer and ran our best pass, and then that was it – we didn’t make another A-to-B pass all weekend long. Oddly enough, it was still a good time,” Leeper says.

However, even with the challenges, he still clicked off a 1.15 60-foot clocking and 4.71 elapsed time in the eighth-mile, all while pedaling the car three times.


The plan for next season is to open it at the NMRA’s Spring Break Shootout in Bradenton, and if the car runs well enough there and then again at the Atlanta stop on the NMRA tour, he’ll make an effort to dedicate himself to completing the NMRA season. And without the support of his girlfriend, Maria, and his business partner for putting up with and supporting his race addiction, this car wouldn’t exist. Work has to come first; without the luxuries it affords him, this amazing car would never have made it out of the planning stages.

There’s plenty of promise in this combination. As Diaz has been well into the 4.40’s with a similar engine combination in his new Edge car, we suspect it’s only a matter of time until Eric Leeper’s Fastback becomes fast to the front.