As the original owner of this 1991 Mustang GT, Brian O'Quinn told us that the car has never let him down. While this is Brian's first Mustang, he is used to vehicles that perform. As a teenager, his first set of wheels rode on a 1972 F-100 pickup that packed 390 cubes worth of V8 under the hood. After he sold the truck to an uncle, Brian dallied with a 1984 Camaro for a while, but found the transmission a little weak. Well, several transmissions, actually. Then, one evening just at dusk, he first saw a black '91 GT sitting with only the parking lights on. He was smitten. When the car drove away, the rumble-song of its dual chambered Flows simply knocked him head over heels.
The GM was soon traded in on the Jet Black GT you see here and Brian hasn't looked back since. At first, their relationship was a little strained. Brian told us, "I learned to drive a standard the second I drove it off the lot. It was an interesting drive home." For the first few years, this GT was Brian's daily driver and, while it started slowly, the mod bug had bitten. Blame those mufflers. "I started with Flowmasters in '92, then the baffle, then a filter and, today, I'm on my third supercharger, second set of wheels and I've upgraded or replaced just about every single part on the car. It's been a great learning experience."
Through the decade and a half that they've been together, about 68,000 miles of Texas blacktop have passed beneath them. Other trucks have come and gone as Brian works to keep the mileage reasonable on the GT. One of the things that he hasn't changed, though, is the paint. "It has its share of nicks and tiny dents," Brian mentioned, but "it is the original paint from Ford and is often mistaken for a new paint job."
Growing Together
While Brian has a mechanical background, his familiarity with things automotive was sparse. The Mustang spurred him to learn more. "I knew nothing of Mustangs, but soon learned everything there was to know by reading books, magazines and watching friends working on their Mustangs. I read Ford catalogs from cover to cover to know what every single part was and what its function was. Before I knew it, I was installing a blower, headers, cam, heads and on and on." When he first took delivery, the GT's engine was putting out 190 RWHP. Today, that number has grown to almost 500 RWHP, thanks to the current supercharger, a Vortech S-Trim pumper.
Of course, the supercharger isn't the only component helping out this engine. It's one part in a chain of upgrades that include an E-303 cam, Edelbrock Performer heads, a GT40 intake and BBK 65mm throttle body. With the blower, fuel system changes were also called for and those included 42 lb/hr Ford fuel injectors, 255 lph worth of Walbro in-tank fuel pump, along with an Aeromotive fuel pressure regulator. Even with the boost set at a leisurely eight psi, normal Texas heat makes the use of an intercooler prudent.
Cartech Turbo from San Antonio whipped up a custom design at Brian's request and even drove from there to see him in Austin to provide customer support. If your Lone Star state geography isn't all it might be, that's a two and a half hour round trip. The 3-inch tubing on the intercooler ensures maximum flow with little restriction. Valve train upgrades, including Ford Mototsport 1.6 ratio roller rockers, have allowed the maximum RPMs to climb to 6800, while the Edelbrock heads boosted compression by a half-point to 9.5 to 1. In their own ways, each of these changes contribute to make the output power level what it is today.