The History of IROC: International Race of Champions


If you were growing up in Queens, NY during the 1980s and early ’90s like I had, then you know that the term, “IROC” was ingrained in many a young car guy’s soul. The name took on dual meaning; the first as a derogatory reference to Italian-American males cruising up and down the strip. The second, referred to the car which all of your author’s peers counterparts, Italian or not, yearned for; the Chevrolet Camaro IROC-Z.

Really acting as an acronym for International Race Of Champions, this sort of “all-star game of auto-races” began life in 1973 as the brainchild of David Lockton, developer of the Ontario Motor Speedway and organized by racing greats, Roger Penske, Les Richter and Mike Phelps. The competition consisted of four annual races, initially run on road courses, then primarily on American oval tracks, following stock car racing rules.

The IROC series called upon drivers from varied racing disciplines; including Indy Car, Formula 1, SCCA, World of Outlaw and of course, NASCAR, which eventually contributed the majority of the drivers to the mix. Twelve racers were invited to compete, usually chosen from recent season championships in their respective series and major events, such as the Indy or Daytona 500.

The cars were identically-prepared, evenly matched stock cars of the same make and model, set up by a single team of technicians (historically, NASCAR veterans Dick Trickle, Dave Marcis and Jim Sauter) in an all-out effort to derive a world champion based solely on driver ability.

Beginning with the 1976 IROC season, a winner was determined by a total points-system in the four events. Throughout its three decade-long history, the nationally-televised IROC races were widely acknowledged, as some of the most thrilling auto competitions ever run.


Kicking-off the series’ inaugural season, the first race of the 1974 campaign took place at Riverside International Raceway in Riverside, California, on Oct 27, 1973. The race was televised via tape delay on ABC, who provided coverage until 1980 and again from 1987-2003, splitting the other years with CBS (1984-86), ESPN and Speed Channel (2004-06). The first cars chosen for this automotive duel for supremacy, was the Porsche 911 Carrera RSR. Fifteen RSR’s were built, all basically race-tuned versions of the street-going RS model.

The powerplant propelling the potent Porsches, was a race-ready version of the RS’ 3.0L flat-six with the famous “High Butterfly” injection system making 320hp. Wielded by a five-speed manual transmission, the 2100-lb. racecars combined RS and RSR components; including wide-panel bodywork, a fiberglass whale tail, Fuchs forged wheels, 4-piston aluminum brakes and a sparse all-race interior with plastic door handles to save weight.

First to claim IROC victory, would be 1972 Indianapolis 500 winner Mark Donohue in his #2 Porsche. Unfortunately this was the racing legend’s final win, as he lost his life the following year in a practice race for the Austrian Grand Prix.


For IROC’s second season-1975, the decision was made to change from the pricey Porsches to a homegrown platform. With the absence of competing pony cars by 1975 leaving the segment wide open to the General and Chevrolet, the 2nd-Gen Camaro was chosen as the great equalizer for auto racing’s best.


The first Camaros used from 1974-’76 were production-based, steel bodied cars, specially prepared by Penske Racing and IROC. Roger Penkse was no stranger to the Camaro, having found success with Chevy’s pony car in the 1968-’69 SCCA Trans-Am-Series. Initial power came from a Traco Engineering-built, 336ci Holley-carbureted Chevrolet small block making 440-horses and wielded by a T-10 Borg Warner 4-speed manual.

In 1977, Penske and IROC commissioned legendary NASCAR driver/builder Banjo Matthews to build new Camaros from the ground up. The new machines were complete tube frame racecars covered predominantly with fiberglass panels, powered by a re-worked, Traco-built 350-cid Chevy mill good for 450hp. The bodywork, T-10 4-speed gearbox, race suspension, Hurst-Airheart 4-wheel disc brakes and steering box came straight from GM’s parts bin. Fifteen IROC 2nd-Gen Camaros were built, racing the series until 1980.

During the Camaro’s first IROC tenure, open wheel drivers would dominate the series. Here are the victors:IROCDOC-88


  • 1975-Bobby Unser, Indy Racing
  • 1976-A.J. Foyt, Indy Racing
  • 1977-A.J. Foyt, Indy Racing
  • 1978-Al Unser, Indy Racing
  • 1979-Mario Andretti, Indy, F1 Racing
  • 1980-Bobby Allison, NASCAR


After a four-year hiatus, 1984 would see IROC picking up where it had left off. Now co-sponsoring the series with Anheuser-Busch, Goodyear and True Value Hardware, Chevrolet offered-up the 3rd-generation Camaro Z28. This iteration of Chevy’s pony car would later become synonymous with the name, IROC.


The new racecar was built on a Banjo Matthews, IROC –fabricated, Grand National-style tube frame chassis like that of a full Winston Cup car. The combination of factory skins and fiberglass panels, presented a hardcore mirror image of the streetcar.

The fresh set-up included:IROCDOC-90

  • A Katech Inc. race-prepped, forged aluminum 350 cid Chevrolet small block motor
  • 390cfm Holley carb
  • Hedman Hedders
  • Richmond “Super T-10” 4-speed manual transmission
  • Stock car quick-change rearend with 3.50 gears for the oval track or 3.90s for road course.
  • The engine had a 9:5.1 compression ratio and made 470hp/400lb-ft in the 3350-lb. car.

For the 1985 model year, Chevrolet would celebrate the IROC racing Camaros TV-popularity by offering a new high-performance IROC-Z production model as an option package on the Z28. It came equipped with your choice of two 305 cid. V8s; one with a 4bbl. carburetor, another with GM’s brand new Tuned Port Injection (TPI) system, good for an additional 25 hp over the carbureted version’s 190.

It was backed by either one of two gearboxes; a 5-speed manual or a 4-speed automatic. Underneath, was a more taught suspension package that improved the Camaro’s handling substantially.

On top of the Z28’s stiffer suspension, more aggressive front fascia devoid of intake slots, ground-effects and rear deck lid spoiler, IROC-Z’s were fitted with:

  • Front fog lights with lower ground-hugging front air dam and body-color ground-effects skirts
  • New ornamental hood louvers, “IROC-Z” door decals, call-out badges and ground-effects striping
  • Lowered ride height with special Delco-Bilstein rear shocks, tuned struts/springs, larger diameter front/rear sway bars, rear stabilizer bar and a “wonder bar” steering/ front frame brace
  • Specific 16×8-inch five-spoke aluminum wheels with different front and rear offsets wrapped in 245/50/VR16 Goodyear Eagle GT performance tires

IROCDOC-97Changes in decal placement, interiors, wheels, options and safety equipment took place during the IROC’s tenure, with its basic appearance and appeal remaining the same. Few American production cars, especially from the much-maligned 1980s, have solidified such a reputation and legacy, as the Camaro IROC-Z.

With Chevrolet choosing not to renew its contract for 1990, 1989 would be the final year for the Camaro in IROC racing. This would also mean the end of the IROC-Z street car, as Chevy was not licensed to use the IROC name after Jan. 1, 1990. This resulted in a limited run of 1990 IROC-Z’s; completing production by the end of the 1989 calendar year.

Camaro’s second IROC tour of duty would see the primacy of NASCAR drivers, who secured victory in four of six annual contests. This trend would carry-on until the series end in 2006.


  • 1984-Cale Yarborough, NASCAR
  • 1985-Harry Gant, NASCAR
  • 1986-Al Unser, Jr. IRL-Indy Racing*
  • 1987-Geoffrey Bodine, NASCAR
  • 1988-Al Unser, Jr. IRL-Indy Racing*
  • 1989-Terry Labonte, NASCAR

*Al Unser, Jr. would be the last non-NASCAR-based IROC champion.


With GM and Chevrolet’s sponsorship of IROC ending with the 1989 season, a new era and racing platform was introduced for the 1990 campaign. Now stepping into to the batter’s box, Dodge provided it’s Daytona sport coupe as IROC’s chosen steed. The new car was no slouch, immediately making a name for itself, recording faster average speeds than it’s predecessors.


Still built on a Banjo Matthews tube chassis frame, with the new bodywork provided by Diversified Glass Products, the Daytona utilized much of the same IROC/Winston Cup car set-up as before with power now provided by a Dodge 355-cid V8 making 450 hp.

Not unlike Chevy’s efforts and thinking with the IROC-Z, Dodge sought to capitalize on it’s IROC racing status, with a street version of it’s own. Based on the front-drive Dodge Daytona and powered by either a 3.0-liter V6 or turbocharged 2.5-liter engine, the IROC models differed from lesser versions, by adding decals, ground effects and specific alloy wheels.

Also of note, many IROC Daytona’s from 1991-93 were labeled as “Shelby” Daytona’s – basically the same car, except for the decals and a slight change in the VIN code sequence; G743/IROC, G74J/Shelby.

These Daytona’s were the last Chrysler production cars bearing the Shelby name, increasing their rarity and cult-like following. Ninety-three would mark the end of Daytona production and it’s final campaign in IROC.

In 1994, Dodge provided IROC with it’s new-for-’95 Avenger sport coupe. The new racecar had basically the same set-up as its Daytona predecessor with a new body shell from Diversified Glass Products. Dodge did not offer an Avenger IROC production model.


Two IROC seasons later, the Avengers time had come and gone, as did Dodge’s contract. The best was yet to come however, as a new bird was waiting in the wings.


  • 1990-Dale Earnhardt, NASCAR
  • 1991-Rusty Wallace, NASCAR
  • 1992-Ricky Rudd, NASCAR
  • 1993-Davey Allison/Terry Labonte, NASCAR*
  • 1994-Mark Martin, NASCAR

*Davey Allison was tragically killed in a helicopter crash after three races were completed. Terry Labonte was asked to step in and drive, finishing the last race and combining his points with Allison’s winning the IROC title.


Nineteen-ninety six marked the return of GM sponsorship; now utilizing it’s other F-body pony car, the Pontiac Firebird. In the words of great TV chef Emeril Lagasse, IROC was, “kicking it up a notch – BAM!”

The Firebird racecars were brand new from beak to tail, with only the braking components carrying over from the previous platform. Without a doubt the most powerful IROC car to date, two-dozen Firebird Trans Ams were built, once again to Winston Cup Busch Series specs. The new ‘Birds were fitted with:

  • A 350-cid GM Motorsports racing engine with CNC-machined Brodix-cast aluminum Pontiac headsIROCDOC-91
  • A new tube frame chassis built by Laughlin Racing Products-designed for use with non-bias ply tires
  • Titanium intake and stainless steel headers/exhaust
  • A 750-cfm Holley 4bbl carburetor
  • Suspension with independent unequal-length control arms, coil springs, anti sway bar and rigid axle
  • Jericho 4-speed transmission with Dana aluminum quick-change rear end with 3.16:1 axle ratio
  • New Goodyear Eagle racing radials
  • Compression ratio of 9.0:1 making 500hp/445lb-ft
  • Curb weight of 3500-lbs.

Diversified Glass Products once again continued to provide the bodywork, successfully recreating the sleek, aerodynamic lines of the Trans Am street machine and even updated the Ram Air hood/front fascia design with the ’98 model when the time came.

Now an IROC sponsor, Du Pont Automotive Finishes made sure that all of the new birds had brightly colored-feathers for their TV appearances. Where the Camaro Z28 IROC racecar provided a great opportunity for Chevy to bring a production version to pass, the opposite would be true for the Firebird Trans Am.


With it’s already iconic SCCA race-derived name, aggressive styling and Ram Air power, the Trans Am transitioned to race form seamlessly and was a perfect fit for IROC. The new racing Firebirds looked right at home on the tracks – like it was meant to be.

One company did however take advantage of the IROC T/A’s status. Famed Firebird tuner SLP (Street Legal Performance, now rechristened Specialty Vehicle Engineering), offered a new IROC-style rear spoiler for it’s fierce Firehawk models in 2001 and 2002.

As a testament to the match made in racing heaven between IROC and the Firebird, the series continued to run the Trans Am-bodied cars, even after GM and Pontiac pulled the plug on F-body production in 2002. Devoid of any manufacturer I.D., the Firebird’s would race-on till the end in 2006.

In the opinion of this author and and as a Firebird fanatic, the sights and sounds of a flock of twelve 500hp T/A’s soaring over the high banks of Talladega Superspeedway at close to 200mph, piloted by the most skilled drivers in the world, was the pinnacle of IROC racing. Firebird’s eleven-season flight at IROC would see some of the greatest clashes of NASCAR talent in racing history.

Here are the drivers who piloted IROC Firebird T/A’s to victory and some notable stats:IROCDOC-94

  • 1996-1998-Mark Martin*
  • 1999-2000-Dale Earnhardt*
  • 2001-Bobby Labonte
  • 2002-Kevin Harvick
  • 2003-Kurt Busch
  • 2004-Matt Kenseth
  • 2005-Mark Martin*
  • 2006-Tony Stewart

*Mark Martin is the all-time leader in IROC race wins (thirteen) and championships (five), winning three in a row and four total in a Firebird.

*After winning back-to-back IROC championships in ’99 and 2000 driving a Firebird and running the first race of 2001, Dale Earnhardt was tragically killed in a crash at the Daytona 500. Second only to Mark Martin, the “Intimidator” has (eleven) IROC wins and (four) championships. After his death, IROC completed the 2001 campaign with eleven cars instead of twelve.

*Under Crown Royal sponsorship, a 2004 rule change allowing drivers to use their own racing numbers had one exception, anyone using the number “3” would have to use “03” instead.


With the first two races of the 2007 IROC season postponed because of lack of sponsorship, the season never got underway and went on an infinite  hiatus all together. Without sponsorship, a fresh car and a supporting manufacturer, IROC was finished.

In March of 2008, IROC auctioned off all of its tools, equipment and cars and went out of business. Like its last ride of choice, the Pontiac Firebird Trans Am, IROC racing faded quietly into the sunset of automotive history, leaving behind an iconic legacy of exciting memories. Perhaps it can return, someday, racing 6th-Gen Camaros…


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