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Faster than a Corvette? GMC’s Syclone sport truck celebrates a quarter-century

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Photos by Jeff Koch.

Over the years, as the rumors go, plenty of GM-built performance vehicles either got spiked, squashed, detuned, or hush-hushed to protect the Corvette’s reputation as the prime speed machine in the General’s lineup. Only one of those, however, supposedly, as some say, came from truck brand GMC, the 1991 Syclone, which this year joins the list of small-c classics on its 25th anniversary.

While the compact GMC S-15 dated back to 1982, it exhibited about zero difference whatsoever from its corporate sibling, the S-10, aside from a different badge and a slightly different grille insert throughout its first nine years. To help shift both the S-15 and the entire brand out from Chevrolet’s shadow a little, in 1989 GMC introduced three concept trucks: the Kalahari, the Syclone, and the Centaur. The Kalahari, a four-door version of the S-series Jimmy sport-utility vehicle, was essentially a trial balloon for the upcoming production vehicle, while the Centaur, an egg-shaped cab-forward crew-cab El Camino-ish pickup, represented the sort of blue-sky concept car thinking that would never see production. The Syclone, however, showed real lightning-in-a-bottle potential.

Built from a standard cab S-15, the Syclone concept – spelled with an S because Ford still had the rights to Cyclone-spelled-with-a-C – subtracted several inches of ride height and added the late Grand National’s turbocharged and intercooled LC2 270hp 3.8-liter V-6 engine along with a fat lip front bumper and bed-mounted spoiler. Some snazzy graphics lifted from a paper cup laid over monochrome white paint and heavy tint completed the package. GMC claimed it could hit 60 MPH in less than six seconds and cover the quarter in less than 14 seconds at 103 MPH.


Whether GMC intended the Syclone concept to pave the way for a production version, it did so nevertheless. To enhance traction, GMC’s engineers decided to add an all-wheel-drive system using a Borg-Warner 1372/4472 transfer case that split power 35 percent to the front and 65 percent to the rear. The white paint and graphics gave way to black and red and stylists added flares and more cladding to give the Syclone a chunkier look.

As for the Grand National’s LC2 V-6, while it did briefly get a reprise in the 20th anniversary edition 1989 Pontiac Turbo Trans Am, GM had replaced it with the multiport fuel-injected 3800 in 1988, so GMC’s engineers decided to substitute another 90-degree V-6: the 4.3L that already powered hundreds of thousands of S-series pickups. Rated at about 170 horsepower in “high-output” tune, however, the 4.3L would need some work. GMC thus added a Mitsubishi TD06-17C turbocharger, Garrett water-to-air intercooler, and multipoint fuel injection system to boost output to 280 horsepower and 360 pound-feet of torque.


The turbocharged Syclone engine – unique to that truck – along with all the other modifications helped it whittle the concept truck’s performance figures down to a sub-5-second zero to 60 and a 13.4-second quarter-mile.

GMC, busy with renaming the S-15 the Sonoma and with introducing the four-door Jimmy for the 1991 model year, contracted out construction of the production Syclones to PAS Inc. of Troy, Michigan, which built them from nearly finished pickups from GM’s Shreveport, Louisiana, assembly plant. Final cost: north of $25,000, easily double the cost of a regular Sonoma, and just a few thousand dollars short of the base Corvette coupe.

The Syclone launched in January 1991, and word began to circulate that the Syclone had what it took to best a Corvette, namely 12.86 pounds per horsepower compared to the Corvette’s 13.16 and performance figures comparable to the L98 Corvette’s 5.something zero to 60 and mid-13-second quarter-mile.

Ultimately, though, the Corvette proved to have more staying power in the market. GMC built 2,998 of the pickups in 1991, including 10 Marlboro giveaway trucks designed by Larry Shinoda and three Indianapolis 500 sticker-package pace trucks. For 1992 and 1993, GMC switched to building the Typhoon, a two-door Jimmy-based version of the Syclone with the same turbocharged 4.3L V-6 and all-wheel-drive system and similar appearance modifications.

As short-lived as their production lives might have been, the Syclone and Typhoon have endured, not only as a significant part of a second generation of performance-minded pickups (think of the Lightning, the 454SS, and the Dakota 5.9 R/T), but also as the subject of endless tweaking and dragstrip trials to prove their worth against some of the world’s fastest cars.

To celebrate the anniversary, the SyTy group will convene on this year’s Carlisle Truck Nationals, where an entire building will be dedicated to Syclones, Typhoons, and related trucks like the Sonoma GT. Carlisle’s Truck Nationals will take place August 5-7. For more information, visit