photos by: Kevin DiOssi
Taking Something Ultra Exclusive and Making it Truly Unique
Among the most collectible late-model Pontiacs out there, there would be few that would argue that the Mecham Trans Ams are at the forefront. Offered throughout the third- and fourth-generations, the LS-powered variants are certainly the most coveted. Packing nearly 400 hp at a time when a Mustang GT could barely eclipse the 250 hp mark, the LS1 under the Mecham’s hood provided a lot of performance for not a whole lot of money for the era.
Fast forward nearly twenty years (has it really been that long? — yikes!), and they still remain to be among the most-appreciated modern, and final performance Pontiacs. When Mecham launched the car, Dave Stock was among the first to order one, directly from the tiny, Arizona-based tuning company. Being the 9th car produced during the 1999 model year, it left Mecham with a slew of performance and cosmetic upgrades that set it apart from other Firebirds.
As much as Dave enjoyed those upgrades he wanted to turn up the wick considerably, and has stretched the original 346 cubic-inches out to a full 427. Starting with the block itself, it’s standard issue-LS1, albeit, sporting a 4.125×4.00-inch bore and stroke. Inside, it’s stuffed full of high-end hardware that includes a Callies Magnum crank and H-beams Comp Star connecting rods, JE forged pistons and a compression ratio of 11.0:1. A K&N air filter, SLP air lid, FAST 102mm intake manifold and Comptech 90mm throttle body force the oxygen into the engine, while SLP stainless long-tube headers, 3-inch tubing and an SLP Loudmouth muffler bring the soundtrack, and the exhaust flow, up to 11.
Up top, a set of CNC-ported 317 casting heads with high-radius exhaust ports and 72cc chambers optimize maximum-flow characteristics. Harland Sharp roller rockers and Ferrera valves (2.055 intake/1.60 exhaust) compliment the custom-grind nitrous camshaft sitting square in the block. Of course this is only part of the story, as those 427 cubic-inches wouldn’t be as nearly exciting if it weren’t nitrous-injected — which it is. A TNT progressive wet nitrous system, jetted for a 150hp-shot of juice, helped produce over 500 rwhp on motor and, nearly 650 on spray.
With that kind of power on tap you know the factory T-56 would eventually give up the ghost, so in addition to assembling the engine, porting the heads and tuning the ECU, RevXtreme also fortified the 6-speed to handle the power and the abuse that Mr. Stock had intended for it. A SPEC Stage 3+ and flywheel sit between the two major drivetrain components, while Dave shifts the gearbox with a B&M Ripper shifter.
With a stout powerplant, solid transmission and an overall menacing persona, it only made sense to ensure that the rearend was up to par, and Dave has since swapped out the meager 10-bolt for a much stronger 12-bolt, packed with 3.73 gears. Dave did roll with the 10-bolt for a little while, but instead of waiting until it inevitably gave up the ghost, he went and upgraded it, anyway.
One area where (surprisingly), a lot of enthusiasts tend to overlook, is the suspension. Understanding that the off-the-shelf OEM hardware wasn’t quite so sophisticated, Dave upgraded quite a bit of the underpinnings of the Firebird. Bilstein shocks/struts and Eibach springs sit at all four corners, while the stock sway bars, upper and lower A-arms remain in place. A BMR torque arm and SLP weld-in subframe connectors improve the F-body’s rigidity. A BMR driveshaft loop is also bolted into the T/A’s floorboard, as a precautionary just in case the driveshaft decides to eject itself from the rearend.
Although the car hasn’t hit the dragstrip since its completion (well, it could have since we’ve last checked but more on that in a minute), Dave installed Mickey Thompson ET Streets and skinnies, that wrap Weld Racing Pro Star 15-inch rollers. Adding form and function over the already bold Mecham styling, the ProStars aid in traction and weight reduction at the same time.
The cockpit is largely standard issue 1999 Mecham Trans Am, with the addition of several AutoMeter gauges, 5-point harnesses and an AutoPower 5-point roll cage. The added safety goes a long way, especially when the Trans Am hits the dragstrip. After all, what’s the point of making over 650 horsepower to the rear tires if you can’t legally run there?
Unfortunately, Dave ended up parting with the Trans Am just before he had an opportunity to run it at the dragstrip. Offered a bid that he couldn’t refuse, he ultimately replaced it with a C6 Corvette as his next project — and he’s already elbows deep in that one! While we wish we could report own the performance figures, we commend Dave’s perseverance with a car that he had for almost 17 years. How many of us can say we stuck with the same car for that long, without selling, wrecking or otherwise destroying it in such a long period of time. Dave’s former T/A still looked great all the way up until the day he sold it. We just hope the car’s new owner enjoys it just as much as Mr. Stock has.
- CAR: 1999 Pontiac Trans Am Mecham
- OWNER: Dave Stock
- ENGINE BLOCK: LS1; bored and stroked to 427ci.
- CRANKSHAFT: Callies Magnum
- PISTONS: JE (forged)
- CONNECTING RODS: Callies H-beam CompStar
- CAMSHAFT: Custom-grind nitrous cam
- CYLINDER HEADS: 317; Harland Sharp roller rockers, Ferrera valves (2.055 intake/1.60 exhaust)
- COMPRESSION RATIO: 11.0:1
- INDUCTION: K&N air filter, SLP air lid, FAST 102mm intake, Comptech 90mm throttle body
- POWER ADDER: TNT progressive nitrous system; wet, 150-shot
- IGNITION: Stock coil packs, MSD 8.5mm wires, NGK TR55 plugs
- EXHAUST: SLP stainless long-tube headers, 3-inch tubing and SLP Loudmouth muffler
- FUEL DELIVERY: 42-lb. injectors, Walbro pump
- OILING: C5R pump, stock pan
- TUNING: Stock ECU; tuned by Rev Xtreme
- TRANSMISSION: Tremec T-56 6-speed; built by Rev Xtreme
- CLUTCH: Spec Stage 3+, Spec flywheel
- SHIFTER: B&M Ripper
- DRIVESHAFT: Stock
- REAREND: Moser 12-bolt, 3.73 gears
- SUSPENSION: Bilstein shocks/struts (front, rear), Eibach springs, stock sway bars, upper and lower A-arms, BMR torque arm, SLP weld-in subframe connectors
- CHASSIS MODIFICATIONS: BMR driveshaft loop
- BRAKES: stock; cross-drilled/slotted rotors
- WHEELS: Weld Pro Star 15×3.5 (front0, 15×10 (rear)
- TIRES: Mickey Thompson skinnies (front), ET Streets (rear)
- HP/TQ.: 500/593 (conservative tune)
- BEST 1/4-MILE ET: N/A
Rick Seitz is the owner and founder of GMEFI Magazine, and has a true love and passion for all vehicles. When he isn’t tuning, testing, or competing with the brand’s current crop of project vehicles, he’s busy tinkering and planning the next modifications for his own cars.