SRT® Viper GTS-R: Birth of a World Class Race Car
Editor's Note: This two part series of interviews with Alan Macey and Scott Krugger tells the story of the development of the SRT® Viper GTS-R race car.
The SRT® Viper GTS-R team returned to competition in the American Le Mans Series (ALMS) in August 2012. But the beginning for this race team came some months earlier, when a small group of engineers at SRT and at Riley Technologies took on the task of creating the SRT Viper GTS-R race cars. Here are two such people sharing their story from the beginning.
We sat down with Alan Macey, Lead Designer, SRT Viper GTS-R, and Scott Krugger, Design Manager, SRT Viper GTS-R. This day we talked about the beginning of the vehicle design process and the initial morph of a race car from a production car. It went like this:
Q: Where did you both come in on the development of the new SRT Viper GTS-R?
"I was there through the program, but Alan was the key designer. I worked a lot early with the race team on how we were going to establish this car and the process we would follow. We gave Alan the green light to take that on. Alan was instrumental in being the design go-to guy for all the elements that needed adjustments.
"What was really interesting in the beginning was that the race team had never had the design team so engaged. It was kind of interesting for us because we didn't quite understand everything. We assumed, 'This is a race car, it has a function.' It has to function properly. It has to be aerodynamic, but we wanted it to look good, too. We wanted to work as close as we could with the team to make sure of the functionality of the car as well as making it as beautiful as possible."
Q: It seems overwhelming, where did you begin?
"Once we got the initiative of creating this GTS-R, we started by meeting with the race team. We met with the guys and asked them to give us the rulebook. We wanted to establish the footprint of the vehicle. How wide is the track? What are some of the things that we can and cannot do to be legal in the series. Really, that was the starting point. We needed to know what we had and what were areas we couldn't touch. What needs to reflect the production vehicle? Ultimately, we widened the track significantly. The track on the GTS-R is a lot wider than it is on the production vehicle."
Q: What challenges were there to overcome when widening the vehicle?
"Right off the bat we knew we were going to widen the vehicle. We were going to stretch the wheel flares to be dramatic and give it tire coverage. There were a lot of rules we needed to apply in terms of being legal in the series. There are certain heights, center of wheel, a certain amount of coverage over the tires, things like that that we had to adhere to.
"We kind of started out with a quick morph that we gave to the race team. We ran a CFD Study, which is an air-test study, to see if it fit the aero requirements. Does that give you the optimum aerodynamics that you want for this vehicle?"
Q: How did that first design work out? How much did it change?
"There were things that worked and things that didn't work. We kind of said, 'we want you guys to let us know what works.' We asked them to manipulate the surface to show us where they wanted the surface (for the best aero). Obviously, the vehicle had to visibly reflect the production vehicle. Even if you changed it in certain areas, it had to be reflective of the production car.
"The leeway to the exterior design was driven by the functional needs in terms of a wider track, front and rear. Any element that needed change based on the vehicle's specifications or based on dimensions was based on the series requirements. Anything we changed had to reflect the vehicle, but it could be manipulated to be the most aero efficient surface that we could create."
Q: Any other challenges when widening the GTS-R?
"The major areas were obviously over the tires and the corners of the vehicle. The front area where the headlamp zone is was truly established by the race team. We asked them to give us the best surface they could that gave them the most aerodynamic surface that they need and then we'll work within that. We even established some things on the body side. We did a couple of things where we flared the vehicle out. We flared the surface out to cover the tires in the rear and the front. We then realized that that was not the most aerodynamic way to do it. So in the body near the area of the side gill, we amplified those surfaces and pulled them out."
Q: How about the front of the GTS-R?
"The hood was a surface derived from the race team. We had them put the vents in the hood where they needed them to get the right flow, so that the air comes in the mouth and exits over the hood. They defined that surface for us. These are the areas where Alan (Macey) would come in and see if we could tweak some of these surfaces. We'd look at if we could make a surface transition a certain way and things like that. Alan really tuned the surface of this thing. He made sure that everything we wanted to tune did not affect aero negatively. There was a lot of back and forth that Alan played with the race team to make sure the surface not only functioned, but looked really good as well."
Q: Sounds like a good time for Alan to come in. How challenging was this project?
"Going back to the (ALMS) rules, one interesting thing about them is that they are on one hand very specific in a lot of ways, but there are also ways of blowing them open to interpretation. The rear fender is a good example of that. Typically, the rulebook says what the maximum width is and the car is supposed to look like the road car, but you can do whatever you need to do to create the transition between the two surfaces. Where most teams try to create a flare out to their rear wheel, and keep the car looking like the production car, they let that transition take up the entire side of the car and it extends all the way through the door. That's an instance where everybody is happy because we improved the airflow and retained the identity of the car, especially in side view. Even though it's a pretty dramatic change, you barely notice it when you see the car in side view."
"The initial reaction on paper would be that you can only add a flare on there, so the rest of the car maintains the look of the production car. When we started to pull that body side out, and we transitioned it more through the entire door surface, the visual characteristic was reminiscent of the production car. It actually looks just like the production car."
Q: Ultimately, making the car wider wasn't so bad.
"The vehicle getting wider is never a bad thing. We knew that we could visually make it look awesome with the wider vehicle and the wider track. I don't think that was a big challenge for us. Not to sound like there weren't any challenges, we had a very open mind when we took this project on. There were no preconceived ideas of what this thing has to be. We didn't hold anything that sacred, so to speak. First and foremost, this was a race car and we wanted to make sure that it performed and that the surfaces we created were going to honor that idea. We felt confident that we could make this thing look beautiful at the same time. We looked at every element as an opportunity to make it look as good as it can and function as good as it can as well. The gill area was kind of a tough area, or more difficult just from a surfacing point of view. There were some challenges that we started looking at in terms of the headlamp placement, just because of the surface of the headlamp. We worked that out."
Q: It almost sounds easy, was it easy?
"At the beginning, working in these big blocks, the big brushstrokes are always relatively carefree because you are not committed to anything one way or another. Like we said, we had an open mind and the team gradually felt like they could trust us to not screw things up. Like any project, it's all fun and games at the beginning and then toward the end is when you start hitting snags and getting into problems. Getting the final execution and getting it really dialed in at the end is where it gets more challenging. There were two pretty different directions that each wanted to take in relation to the body sides at the front of the wheelhouse opening."
Q: From any angle this race car looks like a production SRT Viper.
"The design team really wanted to keep that wheelhouse opening closed out and retain the purity of the body side, but there is a lot of air that is trying to get out from behind that tire. It was creating a lot of drag, and the way the rules are set up, it actually prefers that we deviate to a production body side there. The race team really wanted to take advantage of that. There has to be coverage like a tire plane and coverage to a certain point, just below the centerline of the front and rear spindle. There has to be a height that the surface comes down to and below that can pretty much be gone. That's where it can go back inboard into basically where the production surface is.
"For us that was initially the race team's initiative that they wanted to leave that open. From a design perspective, we wanted it to be closed and consistent and smooth there. It did reflect the production car even more and more tailored and finished. But, we were open-minded and wanted to see what doing both ways would do. Let's see if one really shines more than the other. I don't think it was a huge detriment to have it fully enclosed, not as much as the race team initially anticipated."
"It was definitely dramatic and was open for a reason. I think it was one of the only cases where we really had to concede to the race team in terms of the direction of the styling."
"We went back and forth on that several times, and the more we evolved that surface, the better it looked. It looks the part. The race team really appreciated it when they saw it. The first model or mule that was created, it looked really extreme and aggressive."
"It does a really nice job of showing how much wider the race car is than the road car. In that respect, it's nice. It's also a detail that is seen on almost all of our competitor's vehicles. Everyone is kind of using that little loophole in the rules to tuck that surface in there as much as they can."
End of Part I - Part II