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The Story Of Callaway’s Corvette C7 GT3

Ernst Wohr tells the fascinating story of Callaway's latest project

Callaway-Corvette-C7-GT3-Red-Bull-Ring-ADAC-GT-Masters-2016

With its first season of competition coming to a close, DSC checked in with Callaway Competition’s owner Ernst Wohr, who sat down at length to reveal the story of the Corvette C7 GT3, which as it happens, is an eye-opening one.

So far this year, the car has racked up multiple wins in ADAC GT Masters with the Callaway team, leads the championship and is set to compete in VLN 9 in preparation for a potential Nurburgring 24 Hours appearance in 2017. It’s an incredible machine, especially when the challenges of its inception are considered.

Wohr, while full of pride in how the C7 GT3 has turned out, was keen to point out just how hard the entire process has been.

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Here’s the story of how the Corvette C7, became a GT3 racer:

“The C7 was planned three years ago, and we said we would build one,” Wohr said to DSC. “But it was stopped by the convergence discussions. If that would have happened then GTE and GT3 would have been the same base car more or less, just a different configuaration of aerodymanics. It would have been a Pratt and Miller car in that case.

“We didn’t want to pour money and effort into a project that would not succeed. So we had to wait until the middle of 2014 when the convergence discussions were off the table. We had planned how it would look and what it would be, but that is when we really started to work on the development of the car.”

We didn’t want to pour money and effort into a project that would not succeed.

Once the project was signed off when GT convergence talks died down, the small team at Callaway immediately began working on the car, their first since the C6 GT3, one of the original crop of GT3 cars 10 years ago.

A lot has changed in GT3 racing since then, the budgets are higher, the aero is more aggressive and the cars are a lot faster. But everyone at Callaway who is still around from the C6 era and its developments knows what works and what doesn’t in independent GT3 manufacturing.

Motorsports / ADAC GT Masters, 6. Event 2016, Zandvoort, GER

“The biggest thing that drives us is our passion for the car, Corvette and the success we had with the C6 base means we know all the steps of developments and evolutions,” said Wohr. “Back then Ratel said ‘take a street car with 600 horse power, put a set of slicks on it, a safety cell and let’s go.’

“It should not cost more than 150 grand,’ he said, but we were adding things every race because the car wouldn’t last. Until 2012 we continued to apply for new homologations to the same car, it was a big evolution over the years and cost a lot of money.

We only have six parts that are original GM in the car and in the bodywork it’s only got the rear upper-half of the bumper that’s original

“Then the dream was to start a new car from a clean sheet, with the basic chassis and everything else. We wanted to put the best of the best materials and talent into the car. We only have six parts that are original GM in the car and in the bodywork it’s only got the rear upper-half of the bumper that’s original.

“On the chassis, it’s only the lower control arms that we modified, but the basic pieces, the hollow castings are really nice. The power steering in the modified version are the only original parts.”

The most impressive factor is that Callaway receives very little help from GM in taking on such a project. The C7 GT3 is an almost entirely independent car, with no General Motors involvement aside from the documents that need to be signed ahead of the homologation, giving them permission to complete it on behalf of GM.

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“We are able to produce the cars in a very low volume,” explained Wohr. “We plan to build five at a time. At the moment we are struggling like we did 10 years ago to get basic chassis and not have to buy complete cars and strip them. At some point all the pieces you take off are not saleable, so you just throw them away.

“We tried everything to get cut price cars from Kentucky , but it was not possible. But the development was possible with help from a lot of friends, customers and vendors. So the complete molds for the bodywork, you have to imagine Paul Deutschman, Callaway’s designer since 1988, I think his first project was Sledgehammer which went for the land speed record. Callaway had it from 1988 for a street legal car until the Veyron came out; 254 miles and hour with a thousand horse power and a twin turbo!”

Despite all the dedication, perseverance and hard work, a partnership with GM and Pratt and Miller is not possible, so as far as the future goes, any increased input or support from GM is unlikely. Yet Callaway continues to pursue developing track-only Corvettes out of passion.

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“With Pratt and Miller you won’t have a partnership, that’s competetition, they are hired by GM to build the race cars in America. We would love any sort of relationship with GM but it’s not in their budget or interest at the moment.

“I think Le Mans is the only thing they are interested in, but for us it’s also a challenge to get a group of 10 people to design and construct a car like the C7 GT3.

With Pratt and Miller you won’t have a partnership, that’s competetition, they are hired by GM to build the race cars in America.

“We were hoping it would perform as well as it does, because it was hard, we didn’t get to do a lot of testing. Now we are only slowed down by Balance of Performance, that’s what kills us. The restrictor and the weight wears out the tyres, so at the end of an hour race it’s so difficult to drive. It shouldn’t be that way.

“Paul Deutschman, the designer in Canada, since 1988 has done all the designs for Callaway. Paul came twice to Germany to talk through the concept, the rest was done over the computer on Skype,” Wohr chuckled. “We spent hours and hours talking and me giving him feedback and watching him draw up the car.

Paul came twice to Germany to talk through the concept, the rest was done over the computer on Skype.

“I remember that the big project was the dashboard, because the original dash contains 36 pieces, and the GT3 car needs to be one mould and it needs to be lower so the driver can see better. I don’t know how many hours we worked on it, and then he sent the data to a vendor and they machine the moulds for us out of PU block material and we made the carbon fibre piece and it fitted. It was a fantastic feeling, it’s the first time that we did all the design work on the computer.

“All the technical parts were done by Mike our director too, and about six to eight people built it all and we realised that because we know Hockenheim so well, it’s our home track, so we did our testing there. We knew references, and we therefore knew were to make the changes. It was all done by feeling and knowledge, not much testing and no wind tunnel testing.

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“We have a great young engineer who did so much work, his name is Paul Schreiber , and everything he said would work on it, worked. We found him at a tuner meeting which Sport Auto organised, I saw the aero he had designed on a Mitsubishi Evo, it was incredible, so I hired him!”

“Since my childhood we always drove Corvettes from the 60s and early 70s and we got addicted to it. We live close to all the key German manufacturers, but we love Corvette. It’s a funny situation.

“We have a good relationship with the German factories though, a lot of their key guys have come through the ranks with us.”

This year, financial constraints have restricted Callaway from competing in international GT3 series. Though there is hope that we will see the C7 GT3 race outside of ADAC GT Masters and VLN in the coming years.

“GT Masters is the only place we can get the budget for, if you came to me and asked me to do Blancpain and you had a budget, of course we would do that. GT Masters isn’t a must, it’s because we have requests and sponsors.

“We also chose to develop the car in VLN, people say if a car works on the Nürburgring it works anywhere, so we use the races a lot to get video footage of how the car performs. We are now preparing the car for the 24 hours next year, the BoP isn’t great but that’s not important right now.

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“It helps us ensure that the car is reliable, running VLN.

“Funnily enough there’s a lot of interest from Australia, Australian GT teams as well as East Asia and USA.”

Racing over in America though, is out of the question, as Wohr went on to explain. Even though it may seem logical that Callaway would provide the car for potential customers in America.

When I got the signature from GM to say that I could homologate it with the FIA, we had to sign that we wouldn’t run it in North America.

“In the USA, at the moment, we can’t race there. When I got the signature from GM to say that I could homologate it with the FIA, we had to sign that we wouldn’t run it in North America. They don’t want competition with Cadillac and their future programmes.

“The plan was to build it in the USA and run in Pirelli World Challenge. PWC are trying to convince GM that they should let us in, but they don’t want it. But PWC want the car there, they were trying to get us to run a car in a race at the end of the year, but we can’t, as we don’t want to hurt our relationship with GM.

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“If we ever go to America, if they retire the Cadillac, we would build a lot more cars, and build them here and in the USA. For now though we have to focus on getting Australian and Asia customers cars. With the current BOP in ADAC it’s difficult to show our true pace.”

At the moment, the only chassis in existence are the three running in GT Masters, though Wohr confirms that more will be built on demand if the deals currently in the works come through.

“If we have people buying them, we will build up to five in time for the start of the European season in late March. It’s a great car, it takes time to build because only the best materials go into it, even though it doesn’t need so much hand fitting.

“We have put everything into this. We are optimistic for what lies ahead..”