Steve Baur
Former Editor, Modified Mustangs & Fords
August 1, 2010
Photos By: Kevin DiOssi, Pete Epple

Some people think they have a fast car. Others, like Sergio Rojas of Royal Palm Beach, Florida, actually own one. Not only is Sergio's Mustang fast, but it also sees regular street duty, and still retains the cool air-conditioned breezes that make cruising in South Florida comfortable.

Having owned several Mustangs prior to this '88 model, Sergio laid out a plan to build his next toy. The foundation had to be a Fox-body and a coupe in particular, but the latter requirement gave way to something a bit more unique.

"I knew both of the previous owners of the Saleen and they had track-raced the car quite often," recalls Sergio. While the hatchback saw a lot of action, it didn't get much in the way of care and maintenance. The air conditioning was shot and one of the seats was broken-Sergio hauled this original Saleen Mustang away for just $3,400. "I first thought I would clean it up, maybe paint it and try to make some money on the car," says Sergio. The first estimates for new paint came in, and Sergio realized that the shop wanted just as much money to paint the car as they did to remove the Saleen decals. With that, Sergio signed up his then-girlfriend, and the two spent about six hours painstakingly removing the stickers.

His purist friends wanted to see the Saleen restored to its former factory glory, right down to those Saleen decals. This probably would have been the thing to do for resale value, but Sergio decided to hold onto the Fox-body and build his dream Mustang from it. The graphics never made it back on. Ronnie's Paint of Boynton Beach, Florida, handled the bodywork and repaint, and coated the Mustang's flanks with six layers of Dupont/PPG base and clearcoat in the original black hue.

When Sergio bought the car, the '88 engine had already been yanked and replaced by a '91 vintage 5.0L with a mass air conversion.

"I ported the mass air meter and intake inlet, and added shorty headers and 3.73s," says Sergio. In this form, it covered the quarter-mile in 13.20 seconds at about 103 mph. A small nitrous kit came next, and on a 125hp shot, it ran 12.6 at 112 mph. Content with the horsepower mods, Sergio turned his attention to various details that needed attention.

"The Saleen bird-bath wing used to fill up with water all of the time, and the hard water would leave marks on the wing," recalls Sergio. To remedy that, a Steeda Autosports Aero spoiler replaced the whale tail. Another item that Sergio thought he could improve upon were the seats. Sergio claims the original Flo-Fit seats were a bit heavy, so he swapped them out in favor of Corbeau Forza buckets. A five-point rollbar is cleverly hidden within the confines of the deep-black interior, and the leftover nitrous bottle in the back hatch is used for "negotiations."

The stock Fox brakes were also changed to SN-95 spindles and Cobra 13-inch rotors and twin-piston calipers up front. That was the extent of the modifications, until Sergio's need for speed led him to a supercharger upgrade.

In addition to a potent Vortech YSI centrifugal supercharger, the engine was also overhauled with a complete 306ci short-block wearing AFR 185 cylinder heads. Weight was pulled from the front end thanks to the addition of a UPR Products tubular K-member and front control arms, and Sergio claims that changing out the rear control arms for UPR Pro Series units with spherical rod-ends was worth a tenth in his short times.

At 17 psi of boost, this combination was good for 11.20s at 130 mph, at least on the first hit. Sergio told us that heat soak would get the best of the engine, and it would slow down quite a bit after each pass.

"I ran it for about four years in this configuration," notes Sergio. "People loved the car and the noise, but it wasn't fun to drive a lot. It (the YSI) was a really noisy blower."

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In 2007, Sergio started thinking about turbocharging. He had always considered them more of an import item, but after going for a ride in a friend's turbocharged Merkur that featured an adjustable boost controller, Sergio was sold on the power and having the ability to change power levels at the touch of a button.

"I liked the idea of using the waste byproduct to make power. There's less strain on the crank as well." With a plan to turbocharge his Mustang hatched, Sergio considered his engine options and sought out some advice.

"Jeremy Martorella (of UPR) explained that if I added up all of the money spent on the four stock blocks that I split, I could have paid for the good block already," says Sergio. With that said, Sergio called Kuntz and Company in Arkadelphia, Arkansas, and had the famed engine shop assemble an 8.2-inch-deck Dart block with an Eagle crank and H-beam connecting rods, Probe pistons, and a bore and stroke configuration that resulted in 331 ci.

Total Engine Airflow (Tallmadge, Ohio) worked its magic on a set of Trick Flow Twisted Wedge cylinder heads, and a custom bumpstick from Cam Motion actuates the valves. Edelbrock's Victor Jr. 5.0 EFI intake manifold was then placed on top with 75-lb/hr fuel injectors and an Accufab 75mm throttle body. A full complement of MSD products lights the air/fuel mixture, while a sumped stock tank is drained by a pair of Bosch fuel pumps. Thanks to the MegaSquirt engine management system, Sergio is able to run the car on just one pump up to 3 psi of boost; then the second pump kicks in. This helps prevent heat buildup in the gasoline.

Power By the Hour (PBH) of Boynton Beach, Florida, handled the fabrication of the turbocharger system, which employs a Garrett 76mm turbo and an air-to-air intercooler. Boost pressure is regulated by a Turbosmart eBoost electronic boost controller, and Jake Long of PBH programmed the MegaSquirt fuel injection computer to engage the custom methanol injection at 11 psi to help keep air charge temperatures down.

At this time, the Saleen was converted from a manual to an automatic transmission by using one of PBR's custom 4R70W overdrive units with an FTI 3,500-stall-speed torque converter. Sergio also opted to upgrade the 8.8 rear axle with 3.27 gears and Moser Engineering 31-spline axles. If you've already checked out the pictures, then you've seen the Pony wheels and Nitto drag radials. The wheels are Mavromont Industries' Pony R hoops, measuring 17x6 up front and 17x10 out back.

In this configuration, Sergio's Saleen put down a stout 767 rwhp and 814 lb-ft of torque through the Magnaflow exhaust system. This translated to a 9.71 at 143 mph in the quarter-mile, but apparently that wasn't good enough, as Sergio recently upgraded the turbocharger to a Borg Warner 80mm unit, and has O-ringed the block in hopes of reaching 900-plus rear-wheel horsepower on E85 fuel. "I want to go 8s on the 17-inch Nitto drag radials," claims Sergio.

It's apparent that Sergio's success in building such a powerful and fast street car is the result of a team effort. The Power By The Hour crew no doubt has a lot of wrench time on the ride, and Sergio credits/blames Kevin Dunn for his Fox-body obsession, and for "helping me spend tens of thousands of dollars over the years." At the end of the day, though, Sergio Rojas can drive his sedate Mustang pretty much anywhere he wants.

Working in the medical field, Sergio finds that a lot of people think they have fast cars. We're guessing there's more than one Porsche owner who's had his ego broken.