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Inside the Camaro GT4.R: GM’s Sixth-Gen Pony Car Goes Road Racing

John Machaqueiro May 25, 2017
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Since the introduction of the Sixth-Gen Camaro in 2015, Chevrolet has steadily rolled out a number of special model designations. At the moment, the most potent offering in the Camaro arsenal is the recently announced ZL1 1LE, powered by the supercharged 6.2 LT4 V8 rated at 650 hp and 650 lb-ft of torque. With enhanced aerodynamics and handling the ZL1 1LE has bragging rights as the most track-capable production Camaro ever. Hot on the heels of that announcement, Chevy unveiled the purpose-built Camaro GT4.R racer, which has been homologated to global GT4 regulations. Developed by the SRO Motorsports group and sanctioned by the FIA, this class is structured around factory-built racecars that are available to the public, though not street legal.

01 Camaro Gt4r Blackdog Speedshop Racing 2/92

The Camaro GT4.R proved that it was fast out of the gate. Blackdog Speedshop driver Lawson Aschenbach took home a pole position and a second place finish on the cars maiden race.

02 Camaro Gt4r Stavenson Motorsports 3/92

Stevenson Motorsports scored a top five finish in their first outing with the Camaro in the IMSA Continental Tire Sportscar challenge race. This is a single car effort in this series and runs on IMSA's BoP for the class. (Photo: Richard Prince)

03 Camaro Gt4r Lt1 Engine 4/92

At the heart of the GT4.R lies an LT1 built at GM's Powertrain Performance and Racing Center. It borrows the dry sump system from the Corvette, which you can see at the front of the engine. Visually and internally it isn't far off from what you can find in the production Camaro SS.

04 Camaro Gt4r Front Splitter 5/92

Developed in the wing tunnel, the front dive planes and front splitter are a key element in the aero package that the engineers at GM developed. These pieces are very similar to what is installed in the 1LE.

Backing up the race-prepped LT1 is an Xtrac sequential six-speed transmission with pneumatic paddle shifters. As with the LT1, the use of a sequential transmission also required a waiver from the SRO Technical Department. At the rear, a limited-slip differential is also sourced from Xtrac. In terms of braking, the engineers went with a combination of the existing ZL1 four-piston fixed calipers at the rear, and larger Brembo six-piston units up front.

05 Camaro Gt4r Rear Wheel 6/92

At the rear of the Camaro, 18x11 Forgeline wheels are at the allowable limit set by the rules. On the Blackdog Speedshop cars, they will wear Pirelli P Zero racing tires, while in the IMSA series, Stevenson Motorsports will use Continental tires.

06 Camaro Gt4r Steering Wheel 7/92

A common sight on today's racecars, the ergonomic steering wheel houses a number of vital switches. On the GT4.R the driver has at his fingertips the adjustable traction control. Behind you can see the paddle shifters that operate the sequential six-speed gearbox.

07 Camaro Gt4r Door 8/92

The production doors have given way to carbon fiber replacements. SRO grants a waiver for this change as long as they are attached in a way that is at least as strong as the original, and any non-moveable element is attached with the use of tools.

One of the biggest challenges when building a racecar to run on a global stage is to predict how it will handle with a variety of different tire brands. Having raced the previous generation Camaro in both the Pirelli World Challenge GTS class, and IMSA's Continental Tire SportsCar Challenge GS Class, there was plenty of suspension data available to create a baseline for the GT4.R; however, the engineers were limited in what they could do because of the restrictions outlined in the rules. Items like the position of the suspension and the steering box anchoring points on the chassis must remain in their original location. Most of the components used are also required to be off-the-shelf OEM pieces. In terms of adjustability, the road car features lightweight dampers at all four corners. Mounted on adjustable camber plates, the front dampers also allow for front-end ride adjustments. These features were all eliminated on the racecar. Ride height is set in the homologation process as well as the use of springs. There are only three different sets of springs (front and rear) that are homologated. As part of that approval process GM was allowed to install two-way adjustable hlins Racing coil-overs. The other part of the handling equation comes down to the wheels. While the road car comes with 19x11-inch forged aluminum fronts, and 19x12-inch rears, the GT4.R includes Forgeline 18x10-inch fronts, and 18x11-inch rears.

All these different components make up the homologation packet that GM delivered to SRO for approval. Once approved, the technical aspects were locked in, and going forward teams are not allowed to make any modifications. The manufacturer can make small adjustments, which need to be approved by SRO, but then have to be implemented on every vehicle they've sold that is actively being used in competition.

09 Camaro Gt4r Center Console 9/92

This center console is within the driver's reach and houses some of the controls for the car. Most notable in the center are the controls for the ABS, along with the ignition and onboard fire suppression switches.

10 Camaro Gt4r Racing Seat 10/92
11 Camaro Gt4r Roll Cage 11/92

At the moment a price hasn't been established. Mark Kent, Chevrolet's Director of Motorsports Competition, recently alluded that you might be able to walk into a dealership and place and order for a GT4.R, just like you can with a COPO Camaro. They've had plenty of tire kickers that have expressed an interest in buying a car, both for competition and as a collector item, but it is difficult to determine how many of those are actually serious inquiries at this point in time.

GM has stated that 2017 will be a development year for the Camaro with two teams doing the work. In Pirelli World Challenge, the Lincolnshire, IL based Blackdog Speedshop Racing team will compete with two cars in the GTS class. Team owner Tony Gaples will drive one car, while Lawson Aschenbach will pilot the other. In the IMSA Continental Tire SportsCar Challenge, the Jacksonville, NC based Stevenson Motorsports team will field one Camaro GT4.R in the GS class for drivers Matt Bell and Robin Liddell. Since the previous generation ran in both series, GM used both brands of tires in the development of the GT4.R. Also worth noting is that Aschenbach did the bulk of the development driving on this new car. Having driven the previous car in both series, we asked him about this new car. He states that, "From a driver's perspective, the new GT4.R is a big step up in performance and drivability compared to the previous generation Camaro. It is much more refined, which allows the driver to focus all of his attention on racing. You'll also become more precise because of the paddle shift function. The Camaro GT4.R has more stability due to the setup and aero development. That gives the driver more confidence when attacking brake zones and entering high speed corners. The setup development also improved the tire longevity - an issue we had with the Fifth-Gen car. Lastly, the power and tune of the LT1 gives you better response and feel. It has similar acceleration to the previous car, but now we've got the top speed necessary to create passing opportunities."

13 Camaro Gt4r Rear Trunk 12/92

The fuel filler inlet has been moved to the rear of the car. The fuel cell is an FIA compliant unit that has to be installed in the same spot as the original fuel tank. Depending on which series the car will compete in, this change will allow teams to refuel during a race in a more efficient manner.

14 Camaro Gt4r Rear Wing 13/92

Develop in the wing tunnel, the rear pedestal mounted wing attaches to the stock steel trunk lid as found on the production car. This wing is significantly larger than the one that comes on the 1LE equipped Camaro, and has a greater deal of adjustability. It is a key component in the aero package designed for the Camaro. Also worth noting is the polycarbonate rear window which reduces weight.v

15 Camaro Gt4r Adjustable Dampers 14/92

As set by the rules, the amount of adjustment on the dampers is limited. GM opted to switch over to hlins Racing coil-overs as part of their homologation process.

The true test of any racecar ultimately depends on how it performs in competition, and how successful it is at the drop of the checkered flag. In early March, the crew at Blackdog Speedshop took delivery of their cars a few days prior to the opening round of the Pirelli World Challenge season in St. Petersburg, FL. Aschenbach validated the effort with a pole position and a pair of second-place finishes in both races. That success was followed up at Virginia International Raceway with a pair of third-place finishes, and the points lead in the driver's championship. In the IMSA series, the Stevenson GT4.R also saw its first outing at the Continental Tire SportsCar Challenge race at the Circuit of the America's. Matt Bell qualified the Camaro in the fifth spot, and Robin Liddell brought it to the checkered flag, also finishing fifth.

16 Camaro Gt4r Hood 15/92

As mandated by the rules, the OEM hood must be retained. This is the same metal hood with a carbon fiber extractor that is found on the street Camaro ZL1.

This performance straight out of the box indicates that Chevrolet has built a car that is both fast and reliable, which will be a key selling point once the cash register is set up for business.

 Camaro Gt4r 16/92
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