It's no secret that the GM LS series of V-8 engines are very strong runners right out of the box. One would be hard-pressed to find a late-model Trans Am or GTO that can't run a 13-second quarter-mile in stock form. What's even more attractive to performance enthusiasts is just how easy it is to wring more power out of them using traditional bolt-on upgrades. It's not unheard of for these engines to power cars to 12-, 11-, or even 10-second quarter-mile times with a stock or nearly stock bottom-end.
Jason Seger of Mount Holly, New Jersey, is someone who has embraced the bolt-on potential of the LS1 V-8, perhaps to an extreme level. He has scienced-out a combination that uses a stone-stock long-block and puts out a stout 537.4 hp at the wheels! It's an interesting story that shows how some careful planning and realistic goals can make a flexible, reliable combination that can be duplicated by any hobbyist.
"This isn't my first Firebird," Jason explained. "My first one was a '96 V-6-powered car. My father bought it for me; he wouldn't let me get a V-8 because I was just a kid at the time. Unfortunately, my dad died in 1997 and he didn't get to see this one."
With its Chromalusion Absolute...
With its Chromalusion Absolute Purpleen flames, Jason Seger's '99 Trans Am will never again be mistaken for someone else's Firebird. If you pull up next to this one on the street, rest assured that it can back up its in-your-face attitude.
By 1999, Jason was of sufficient experience that he felt an LS1 Trans Am was the right choice for him. He knew he'd be modifying the Pontiac, so he passed on the WS6 version, opting for a standard Trans Am and saving a few thousand dollars in the process. Within a year, he was trying to keep up with his buddies who were driving supercharged Mustangs, and so the mods began.
At first, he concentrated on intake and exhaust upgrades. An SLP Performance Parts Ram Air HO hood and airbox were added to get the air in more efficiently, and the exhaust is ably handled by a set of Mac 1.75-inch primary, mid-length headers with 3-inch collectors and Jet-Hot coating. They are connected to a high-capacity MAC 2.5-inch Y-pipe, which is also Jet-Hot coated. The Y-pipe flows into a pair of MAC 2 high-flow converters and a 3-inch Flowmaster three-chamber muffler with dual outlets.
The above mods helped out quite a bit, jumping the output up to an impressive 316 rwhp as recorded on a Dynojet chassis dynomometer. It was an improvement, but Jason wanted more. After all, those Mustangs were using centrifugal superchargers and were making serious horsepower. Inspired, he launched into Phase II of his modification plan for the Trans Am, and this is where things got interesting.
This is the view many Mustang...
This is the view many Mustang owners get of Jason's Vortech-blown Trans Am. Its rear suspension has been extensively modified to handle the excessive horsepower and torque.
Figuring what's good for the Pony is also good for the Bird, Jason purchased a Vortech aftercooled centrifugal supercharger system that features a G-trim compressor. The entire unit is polished, and the boost is set at a conservative 5 psi. Of course, the addition of the blower required upgrading the injection system. Stock 28-lb/hr units gave way to 38-lb/hr injectors, and the fuel system was similarly upfitted with the installation of a T-Rex inline pump. The Vortech-supplied computer programming was replaced with a custom tune by East Coast Supercharging.
Also added was a Compucar single-stage nitrous system with choice of 50-150hp nozzles--a 100-horse shot is in there now. The purges are located under each parking light. Even with such a low boost pressure, the LS1 responded with a sharp increase in horsepower, 457.8 at the rear wheels on motor alone as measured on the same DynoJet. Increasing boost to 9 psi and upgrading to Motron 60-lb/hr injectors and a Racetronics 255 gal/hr pump resulted in a whopping 537.4 hp at the wheels without nitrous. This power increase was achieved retaining the factory-issue 75mm MAF, 75mm throttle body, LS1 intake, and an untouched factory long-block featuring 2.00/1.55 valves in the heads and a stock 209/198-degree duration at 0.050 cam with 0.500/0.500 lift using 1.70:1 rockers. The ignition system is stock as well.
Believe it or not, there is...
Believe it or not, there is a V-8 engine under all of that ductwork. A G-trim Vortech supercharger puts out a boost pressure of 9 psi, but there's room for much more should the bottom end be upgraded. Note the Purpleen-painted airbox, which matches the flames.
The interior is tastefully...
The interior is tastefully upgraded with a leather-wrapped six-point rollcage and the removal of the rear seat.
The ashtray has a sneaky surprise....
The ashtray has a sneaky surprise. Instead of ashes and spent Luckys, it houses the arming switches (left and right) and the selector switch (center) for the Roll Control and the nitrous system. A button on the shifter activates both depending on the selector's position.