IMSA’s fabled class stuns at Rolex Reunion

Twenty-two brightly colored race cars roar by, V-8, V-6, and rotary engines belching, whining, and buzzing. Leading the pack is a lone Nissan 300ZX followed by Corvettes, Camaros, Cutlasses, Mustangs, a few RX-7s, and a smattering of other hot production cars. The wide-bodied cars twitch and squirm as amateur and professional drivers wheel them around the 11 turns and 2.2 miles of Weathertech Raceway Laguna Seca. They treat the track’s corkscrew section like it owes them money— charging corners, clipping curbs, and occasionally dropping a wheel off the track into the loose California sand. 

This is the IMSA GTO/GTU class at Monterey Historics Rolex Reunion, and this is one hell of a way to celebrate a 50-year anniversary.

2019 marks IMSA’s golden anniversary. The road racing series founded by John Bishop, his wife Peggy, and Bill France Sr. half a century ago has celebrated that anniversary with everything from retro liveries on modern race cars to special historic racing events since the opening race this year at the Daytona Rolex 24. 

The 2019 Monterey Historics needed to be commemorated in special fashion, though. “IMSA has raced in the bay area for over 45 years. The connection to the area is strong,” says IMSA Senior Director of Race Operations Mark Raffauf. The first IMSA race held at Laguna Seca dates back to 1974, coincidentally, the same year as the inaugural Historics (and the same year Raffauf began his IMSA tenure).

To turn heads at (arguably) the most iconic vintage road race in the United States, with which IMSA has such an intimate relationship, IMSA brought out the big guns. Event partnership, monolithic heritage displays, and enough iconic IMSA cars to clog the paddock—110, to be exact.

Sure, the Prototype class has more speed, and the Formula Ford class has more heritage (it was actually the first sanctioned IMSA race); but of the 100-plus vintage cars, no class was more raucous than the IMSA GTO/GTU cars. The rules package evolved more than Darwin’s finches, so for the sake of word count, let’s stay out of the muck and mire. 

What you need to know: The eighties and early nineties GTO/GTU cars that raced at Laguna Seca this past weekend are widened steel and fiberglass bodies draped over largely tube-built chassis. “GT” stands for Grand Touring while the “O” and the “U” reference a set engine displacement as “over” or “under.” The noisemakers under the hoods have massive disparity. So long as the engine correlated to the body’s manufacture family, teams could run their engine of choice. Jack Roush reportedly ran five different engines in one year, ranging from a 7-liter V-8 small-block to a turbocharged four-cylinder. Smaller engines merited a weight handicap, and bigger cars warranted bigger tires. Ah-ha, let the gamesmanship ensue.

Also of note—some TransAm cars found their way into the mix at the Historics. For example, the Duracell-sponsored 1991 Camaro is actually a vintage TransAm car with 4-barrel carburation, whereas the Skoal-sponsored 1986 Camaro is an IMSA GTO car with larger tires and fuel-injection.

TransAm, SCCA, Tommy Kendall, droves of fans—doesn’t matter who you are. At IMSA’s 50th birthday party, everyone’s invited.