photos by: Joe DiDario

Improving Upon what ASC/McLaren has Started

Now that we’re creeping up on the thirtieth anniversary of the last Turbo Buick rolling off of the assembly line, the amount of covet and love for this car has anything but waned. Available in various colors, options and trim levels, you could have ordered a factory high-13 second car that looked like the one your grandma drove, or you can pony up for the Darth Vader edition, the GNX.

Based on the already all-black Grand National, ASC/McLaren took the 245 hp GN boosted V6, and cranked it up to an advertised 276 hp. However, some say that the real number was closer to 300 hp,  perhaps a little more. Even more impressive was the torque numbers, though. Advertised as 355 lb-ft in the “normal” GN, the GNX bumped it up an extra advertised 5 lb-ft., but not many would dilute the fact that that number was over 400.

Equipped with 16-inch GTA wheels, fender vents, wheel flares, specific GNX badges and thankfully, a proper gauge cluster courtesy of Stewart Warner, the cosmetics also added some functionality to the car. On the performance side of the spectrum, you also earned a less restrictive exhaust system, a larger turbocharger, modified intercooler, a tweaked transmission, ECU reprogramming and beefed-up suspension hardware. As a result, the typical 14-second Grand National was then transformed into a low 13-second, high-12 second capable rocketship in an era where a 5-liter Mustang GT was a 15-second car.

To many enthusiasts, a performance vehicle that “only” runs 13.3 in the quarter-mile just isn’t enough. One of those guys is Stratos Colman, who picked up the boosted legend back in 1999, after seeing the car in an early online ad. After sealing the deal, Mr. Colman drove the 1-of-547 G-body back to his home in Jersey — almost 600 miles! Once he got the car home, there were some things he would eventually address, however.

Being quite the collector of rare and interesting late-model GM iron, including a Mecham Trans Am convertible and Camaro Z29.R, he felt compelled to improve on the GNX’s capabilities just a bit. Without ruining any of the DNA associated with a 5700-mile original, early production example (car number 017), of course.  Apart from the few upcoming modifications that will be mentioned, most of the car is entirely factory original, including the paint — much to Stratos’ dismay. Despite the fact that ASC had brought out a much deeper finish over that of the OE’s quality, it’s rather thinly applied from General Motors. Add in the fact that the paint on the fillers are fading faster than what he would like (very common on black Turbo Buicks), the car looks fantastic for nearly thirty years old.

Under the hood, it’s largely standard issue GNX-spec LC2, with a few exceptions; a 3-inch diameter cold-air induction system with a K&N filter and a larger MAF sensor for increased flow and improved reliability. Keep in mind, the OE MAF wasn’t entirely reliable and not many Turbo Buick experts would disagree.

Bolted to the OEM exhaust manifolds, is an out-of-production stainless steel, 2.5-inch ATR exhaust system. Clearly intended to not only improve airflow, but to add a few extra horsepower and slightly more audible soundtrack. A 3-inch downpipe is also utilized to bump the power up significantly, especially when you take into account the aftermarket TE49 turbocharger. With the boost cranked up front the original 12-psi. to 18-psi., horsepower is estimated to be around 400 hp to the rear tires. Although it’s been quite a while since the car has been anywhere near a dragstrip or a dyno, it’s fairly difficult to second-guess that claim until it’s strapped down. Either way, its enough punch to compete with the modern musclecars of today.

The shortfall of G-bodies, even a tuner-based modified version like a GNX, was always the lack of cornering capabilities. Despite the improved suspension system that was found in all 547 examples, taking a corner at a higher rate of speed than deemed conventional could end in disaster. That’s why Stratos has implemented hardware from Hotchkis to get the car into the modern era.

With front and rear sway bars, upper and lower A-rms, along with front and rear springs from the aftermarket manufacturer, the car certainly has taken on a new personality. The GNX Panhard bar and torque arm also remain in place, although they wouldn’t be as effective, if not for the BBS RKII 17-inch wheels at all four corners.

Sized at a staggered 8-inch front and 9-inch wide rear wheels that keep the car planted to the ground, while Yokohama 245/45/17 (front), 275/40/17 (rear) stick to the pavement like glue. Naturally, with improved handling and sheer straight-line speed, the front disc/rear drum brake combination just doesn’t cut the mustard today. Which is probably why that Stratos skipped over the typical budget-friendly F-body disc upgrades and jumped right to the heavy-duty hardware from Baer Brakes.

The upgrades have updated the ‘X to such a level that the overall package can be called modern, effective and sufficient for a modern performance requirements. The look, feel, handling, braking and sheer acceleration is on point and would easily disprove any doubters who think the old school G-body is just another pedestrian Buick with a black paint job. Even thirty years after the last one rolled off of the assembly line.

TECH SHEET:

• CAR: 1987 Buick GNX
• OWNER: Stratos Colman
• ENGINE BLOCK: LC2; stock 109 block
• CRANKSHAFT: LC2; stock
• PISTONS: LC2; stock
• CONNECTING RODS: LC2; stock
• CAMSHAFT: LC2; stock
• CYLINDER HEADS: LC2; stock
• COMPRESSION RATIO: 9.0:1
• INDUCTION: K&N filter, 3-inch intake tube, LS1 MAF,
• POWER ADDER: TE 49 turbocharger
• BOOST: 16-psi.
• IGNITION: Stock
• EXHAUST: Stock manifolds, ATR 2.5-inch cutback exhaust and 3-inch downpipe
• FUEL DELIVERY: 55-lb. injectors, Walbro pump, aftermarket sock
• OILING: Stock
• TUNING: Stock
• TRANSMISSION: Stock
• CONVERTER: Stock
• SHIFTER: Stock
• DRIVESHAFT: Stock
• REAREND: Stock; 3.42 gears
• SUSPENSION: Hotchkis upper/lower A-arms (front), springs, front and rear sway bar, Bilstein shocks and  struts, stock GNX torque arm and Panhard bar
• BRAKES: Baer SS4+ (front and rear)
• WHEELS: BBS RKII 17×8 (front) and 17×9 (rear)
• TIRES: Yokohama 245/45/17 (front), 275/40/17 (rear)
• BEST 1/4-MILE ET: N/A

Rick Seitz

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.