Makin’ 800-Plus RWHP with a bolt-on 2013 Shelby GT500 Ford Mustang
By Evan J. Smith
Jason Spina has an affinity for Mustangs. The 39-year-old Floridian has owned over 30 examples of Ford’s iconic pony car, including a 1964 Pro Streeter, dozens of Fox bodies, a Shelby GT350, and his VMP Performance-boosted, 800-plus horsepower 2013 GT500.
“My first Mustang was a 1990 Coupe. It was pretty much unmolested when I got it, but not for long,” Jason told us. “I built it up and it ran 11.0, which was respectable for the mid-90s. It had a Ford Performance “E” cam, “J” heads, a TFS intake, and a 150-shot of nitrous. I let a buddy borrow it and he wrecked it, that’s when I got the ‘64.”
Pro Street wasn’t Jason’s thing. He sold the classic Mustang and worked his way through a multitude of 1987-93 Fox Stangs. He modified, raced and tore up the streets with his Mustangs. That all changed when Ford introduced the 662 horsepower Shelby GT500.
The horsepower and the potential of the 5.8 L supercharged engine impressed Jason, and that led him to find one. “I’ve had the car since 2014; it only had 5,000 miles on it when I made the purchase. The 500 is my baby,” Jason added. “My friends know I say that about a lot of my cars, but I plan on keeping this one.
“It was stock when I got it. I took it to VMP and Justin [Starkey, president of VMP Performance] installed a cold air, upper pulley, and a basic tune. It was heat-soaked and made 585 at the wheels. I drove it that way for a short while then went back to Justin because I wanted a custom tune.” Justin worked his magic and the power went to 692 at the wheels.
“That was a big increase and with BOOSTane added, to increase octane, it made like 704 to the tires,” Jason said with a smile. “I drove it some more and the car sat for a couple of years,” he stated. “I have a short attention span, so I got bored. I picked up a 2017 Shelby GT350, so the 500 just sat. When VMP came out with the Gen3 2.65 L TVS supercharger Justin and I started talking about making 800 horsepower. And that really sparked my interest.”
So with a new goal of 800 horsepower, Jason headed to VMP. We know it’s possible to make big numbers with the factory 2.3 L blower. But big horsepower with the Trinity requires a switch to E85, plus a lower pulley swap, blower porting, improved exhaust, and fuel system modifications. With the VMP Gen3, it’s possible to make over 800 horsepower at the wheels without switching to E85 or making heavy modifications to the fuel system.
We installed a VMP Gen3 blower on Jason’s GT500, along with a supporting cast that included a VMP 160 mm throttle body, 2.8 inch pulley, JLT 123 mm cold air intake, Fuel Injector Clinic 1000 lb/hr injectors, VMP fuel pump boosters, and Kooks long tube headers. The tank was filled with 93 octane fuel and a custom VMP tune was loaded into the computer. It’s worth noting the GT500 made 677 hp at the wheels when it arrived with the 2.3 L blower and a 2.4 inch pulley that produced 16 psi of boost.
Out of the gate, with the VMP Gen3 TVS, the GT500 rolled out 703 rwhp and over 690 lb·ft of torque. Looking for more power, they switched to a smaller 2.6 inch pulley. With just 16 degrees of timing, the engine produced 732 rwhp and 721 lb·ft of torque. Boost was up 2 psi (18 psi total).
Fantastic result? Yes, but Jason was hungry for more. Since boost equals power, we swapped out the 2.6 inch for a 2.5 inch pulley, and to play it safe, they added BOOSTane to increase the octane of the fuel. According to Justin, “BOOSTane is an additive that’s easy to use and it works well. In this case we were able to run an additional 3-5 degrees of timing, and we were never near the edge. Pump gas is not always consistent; at this power level it’s best to play it safe.” The pulley swap and fuel additive helped the GT500 achieve a gain of 33 horsepower and 21 lb·ft of torque at the wheels. The new peak numbers were 765 hp and 739 lb·ft of torque respectively, with just 18 degrees of ignition timing and 19 psi of boost.
According to Justin there was more power to be had, so the shop changed the 2.5 inch pulley out for a 2.4 inch unit. The smaller pulley increased boost to 21 psi and with 19.5 degrees of ignition timing, the GT500 climbed again, making 799 rwhp and 767 lb·ft of earth-rotating torque. This was achieved with a stock lower pulley, stock cams, and no porting to the air inlet, blower, or cylinder heads.
“Justin did a bunch of pulley swapping on my GT500,” said Jason. “He and the entire VMP team have been great. He typically tunes my stuff, and I have all the faith in VMP. Before the blower swap I really wanted over 800-plus horsepower. I was sitting there going, I got 700 to the tire with a pulley and a cold air, and 800 would be great.”
“In addition to reaching my goal, they did a cool video showing the progression of power. In the video it made 799 at the wheels. I’ve actually got a dyno sheet with the single-blade [throttle body] with 814 to the tire. In the end we put the twin-blade back on for better drivability. But, we got over 800 with a pretty simple combination,” Jason added.
Even with the twin 67 mm throttle body the GT500 made 781 rwhp and 769 lb·ft of torque. “It’s great to be able to make a number like that and still have the stock-like drivability that the twin 67 is known for,” said Justin Starkey.
“It’s a monster on the street,” Jason exclaimed. “It’s definitely fun. I have 305 Nittos and I keep the tire pressure around 28 psi. It doesn’t really blow the tires off, at least once I’m in second [gear]. My car still has the factory 3.31 rear gear, that keeps it driveable. I only went down the track a couple of times and I ran 11.00 at 135 mph. It has the factory clutch and I didn’t want to glaze it, so I bogged it out of the hole,” he added.
In addition to the GT500, Jason also owns a 1989 coupe that he’s preparing for Ultra Street and a Coyote-powered, airboat, too. The boat sports a VMP Gen2 that makes 750 horsepower on pump gas. “My Ultra Street Mustang has a 373-cube small-block Ford with TFS heads, a ProCharger F1A-94 and stock suspension. I’m looking to run in the 7s. It’s a big contrast between the Fox and the GT500. You always want more power. I’m thinking about getting the 2019 GT500, so I’ll leave the ‘13 Shelby alone for now. It’s fun to jump in it and go,” he said. With 800 proud ponies at the tires Jason can “go” anywhere in a hurry.