Behind the Scenes with the Diesel-Powered Mazda 6 Grand-Am Racer
Mazda brought three diesel 6s to Daytona. The “factory” car had drivers Jonathan Bomarito, Marino Franchitti, Tom Long, Sylvain Tremblay, and IndyCar driver James Hinchcliffe. The second car was entered with young drivers who have risen through Mazda’s driver-development program: Joel Miller, Tristan Nunez, Spencer Pigot, and Tristan Vautier, but also 65-year-old Yojiro Terada, who has run Le Mans 29 times and is a big icon at Mazda. Car three had drivers Andrew Carbonell, Tom Long, Rhett O’Doski, and Derek Whitis.
After practice at Daytona, we talked with Franchitti and Hinchcliffe about their experience in the diesel-powered Mazda 6. Not surprisingly, they liked the chassis, Franchitti saying, “You can feel the RX-8 DNA in the car. Even though it’s a longer-wheelbase, heavier car, they’ve got it feeling very similar, which is nice because the RX-8 was a really nice-handling car. I think the thing that limits these Grand-Am cars are the tires. And there is more downforce than with the RX-8.”
Hinchcliffe agreed, adding, “The brakes are phenomenal, the transmission is excellent. The big difference, of course, is the engine, which revs so low and yet is still so torquey. It’s a big adjustment. And we’ve come from driving what is essentially the loudest engine ever produced by man (the rotary) to one of the quietest ones.” A point we confirmed as the cars (relatively) whispered past us at speed.
Franchitti thought that, “Sound isn’t a big deal. Maybe it’s quieter outside, but you still have a good amount of sound inside the car so it’s not like you don’t have any reference. You’re aware of the engine noise and can still drive by ear.” Hinchcliffe added that, for him, “You have to rely a lot more on the shift lights on the dash because you cannot hear the motor as much, especially out on the banking with all the wind noise.”
As for the engine, you have to “get used to the turbo and how it spools up,” according to Hinchcliffe. “It requires a bit of a different driving style. You have to keep the turbos spooled up to stay in the power band and you have to work more with the throttle to keep the rpm up, so you get into the throttle a bit earlier.” The shifter came in for specific praise from Franchitti, saying, “It’s beautiful. It blips the throttle because the engine is sensitive to over revving on the downshifts, so you just brake, push the lever, it blips and the gear just slides in. It’s like butter; so nice and natural.”
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The Skyactiv-D Mazda 6s are the first diesel-powered race cars to compete in the Grand-Am series or at the 24 Hours of Daytona. While the race cars were beautifully finished, their lack of long-distance testing showed too soon. The team had been able to fix such initial problems as a troublesome belt tensioner, but a recurring vibration harmonic problem was bothersome. Before sunset, the 6s weren’t part of the parade at Daytona. Reality had hit the fan.
Two of the cars lost a cylinder because of problems with their fuel rails, while the third had a main-seal failure. Mazda wasn’t willing to assign fault to the rails or the seal, and will be chasing down that harmonic problem to see if that was the source. Doonan summed up Daytona this way: “Today will be noted as a learning experience, a data point, if you will. The Mazda and SpeedSource engineers had over 400 hours on the dyno, but only a few on the track.” Now that process will continue.
Even before the problems, Franchitti had said, “This is just the starting point for this car.”
Jim O’Sullivan, who heads Mazda in the U.S. and is quite passionate about the diesel race cars, looked to the next race, which is at the Circuit of the Americas, and said, “Just wait until Austin.”
By John Lamm