While it’s not uncommon to see a modified Mustang, it’s rare to see an engine-swapped 2003-04 SVT Cobra.
Enthusiasts covet the powerful original DOHC 4.6 factory engine that was rated at 390 horsepower—but really made about 425 ponies. Along with the intercooler and supercharger, the engines came equipped with Manley steel rods and forged pistons, which encouraged owners to crank up the boost.
Ford fanatic Paul Guenther knows the history of the SVT Mustang and—while he respects the originality of a clean untouched Cobra—he had different pans for his model.
Paul comes from a line of Ford enthusiasts and has owned and raced his share of Blue Oval machinery. “My father’s been the biggest influence on me when it comes to drag racing. He raced since the 1960s, and the other big influence would be my long-time good friend Ken Miele.
“I’ve always had a passion for Ford cars and Stock and Super Stock racing,” Paul said, “but I always had bracket cars. Stock and Super Stock is a different animal, and Ken has helped me with the transition.
“In the past I’ve owned a 2003 Mach 1, a 10-second 1993 Foxbody with a 393 Windsor, and an ’85 LX with a 396 Windsor that clicked off 9.80s. But I always wanted a Terminator Cobra.”
In the early 2000s, Paul raced clean 1984 Capri that ran 8.60s, but an unfortunate incident led to a crash and the end of the Merc.
“I was racing at Englishtown and blew the ring gear off the flywheel during a run. It just peeled off. It went through the blowproof bell, cut the transmission lines and tranny fluid dumped on the tires,” he explained.
“That was it—I was sideways and into the wall.”
Thankfully, Paul was okay, and he transferred the 532 Big Block Ford into an ex-Roy Hill Pro Stock Truck owned by a friend.
“We put the motor from the Capri in there and ran 8.30s. We later did a 598-cube engine that went 7.80s at 170 mph. It was fun, but I always had a thing for Stock and Super Stock. In the ’60s my dad ran Stock at Atlantic City Speedway in a Cobra Jet. I just have a passion for it,” Paul added.
“In the spring of 2014 I found this Cobra for sale on RacingJunk.com. It was love at first sight. It was the perfect starting point for a Super Stocker,” he said. “I made the trip to Iowa and purchased the rolling chassis that had been newly built and had never seen the track. I still had my work cut out for me to make it NHRA-legal, but it was a good head start.”
NHRA Super Stock allows racers to mix and match engines and bodies from the same manufacturer. And since the Cobra was without its heart, Paul decided to stick with pushrod power.
But this was no drop-in-and-go deal. “I had a few choices when it came to the engine combo. I could have gone with a 302, 351 Cleveland, a 429 big block, an FE or something modern like a 4.6, 5.0 or a 5.4. In the end the 2010 428 Windsor EFI combo was most appealing to me.”
This is a stroker 351W that Ford designated for the Cobra Jet.
“Once I settled on the 428, I called Chris Holbrook at Holbrook Racing Engines and put the wheels in motion.” With this combination, the Cobra fits into NHRA FGT/F within the Super Stock category.
“Jim Morgan at Morgan International Race Engines handled prep on the Ford Performance aluminum cylinder heads. He began with the allowable porting, and he decked the heads to minimize the combustion chamber size (within the limit of the specifications). The ports were then flowed, and finally the heads were assembled and shipped to Holbrook.
“After the engine was together, it was strapped to the dyno for testing and tuning. Holbrook did some R&D, fine-tuning the mill until it produced suitable numbers.”
The driveline was coming along, but the Cobra was also lacking its interior.
Paul located a donor car to gather the factory parts needed to make it Super Stock legal. He also had to remove the tubular K-member and A-arms that were previously installed, as they are not legal. He replaced them with OEM parts, and at that time converted the Cobra to a manual rack from Flaming River that he sourced from Summitracing.com. The intricate Super Stock rules require the front suspension remain stock, although the K-member can be “altered” and you can use bolt-in aftermarket struts and springs.
Glen Weeks at GW Performance Welding modified a stock K-member for oil pan and header clearance, and Paul set the 428 in place. He then turned to Nick at American Racing Headers for a set of custom pipes.
“Nick and the guys at America Racing Headers made an awesome set of stainless-steel, triple-step headers that look good, fit perfectly and make great power,” Paul said.
The 428 sits in a beautiful engine bay that was smoothed, painted and finished with fine detail. It’s like a showplace for the powerplant, and the way Paul sees it, the 428 has a lot to live up to since it replaced the awesome blown 4.6L beast. Up top is a Ford four-hole throttle body that feeds the ported single-plane intake.
Paul runs the required “Z304” heads that are mated to the bored block and a Canton pan seals the bottom end. Holbrook went with a Callies crank, Oliver rods, and Diamond pistons to achieve 12.7: compression from the small block. EFI is from Big Stuff and it utilizes 60 lb./hr. injectors, Aeromotive fuel pump and MSD ignition. It also features a Holbrook-designed custom cam.
The engine spins sky high and produces 840 horsepower and 690 lb.-ft. of torque.
Loving the stock look, Paul left the factory Red paint intact and the body mostly stock. But needing a bit more traction, Paul installed Strange double-adjustable struts along with soft front drag springs. The IRS was traded for a Ford 9-inch that’s suspended by a RJ Race Cars ladder bar with Strange coil-overs and a Chris Alston Chassisworks anti-roll bar.
Rear gears are currently 4.30:1, but that can change depending on track and weather conditions. Stopping power comes from lightweight TBM Brakes and rolling stock was replaced with Weld Wheels Alumistars in the front with American Racing Trackstars in the rear with 28.5×11.5-inch Phoenix slicks that fit nicely in the mini-tubs. “Last but not least, I called Sal Biondo from Biondo Racing Products for all my Sparco safety gear and weather station equipment.”
“The first few runs went well, there was only some minor adjustments needed to be able to make full passes. The Cobra handles great,” Paul stated, “Ken Keir [of Ken Kier Race Cars] was a huge help in getting it dialed in and going straight. Now it launches with the wheels up in true Super Stock fashion and it tracks perfectly straight. It’s a very fun car to drive. I have been running C-4 from Joel’s on Joy, along with an 8-inch converter from A-1 Performance, but we’re switching to a Coan XLT T400,” he added.
Set at a race weight of 3,355 lbs., the Cobra has turned a best of 9.22 at 144 mph. Paul has gone rounds, but his focus is on improving performance and eventually taking a shot at the FGT/F national record. In fact, recent changes include an aluminum spool, aluminum driveshaft, gun-drilled axles, and Santhuff shocks and struts.
“Overall, I’m extremely happy with my new Super Stocker. Chris prepared a fresh engine for 2025 and my goal is to run right around one second under my 10.10 index. And with the power this motor made, I should have no problem getting there.”
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