DAYTONA BEACH, Fla.—SpeedSource Race Engineering has been developing and racing Mazdas since 1995, so it seemed the obvious team for the factory to pick to develop and race the 2013 Rolex Sportscar Series GX-class Mazda6 diesel. SpeedSource came through with nine wins and the GX manufacturers Championship.
For 2014 Mazda wanted to move up to the Prototype class of the New Tudor United SportsCar Championship, using the same SkyActiv-D twin-turbo I4 diesel, redesigned for use as a semi-stressed member and tuned to a much higher output and stuck in a Multimatic/Lola chassis. This was a tall order, and results showed it: the car often DNF'd and usually ran at the back of the GT pack, barely ahead of the mostly stock GTD cars.
In P2 form the engine had plenty of torque—enough to break drivetrain parts—but too little power, and it generated much too much heat. The twin-cam, two-stage diesel used the same cooling system for both the engine and the intercoolers, and there simply wasn’t enough room under the engine cover to keep air flowing to everything that needed it.
Mazda and SpeedSource believed the engine could work, and they kept developing different solutions until finally they got one to work.
SpeedSource and Mazda revealed the fruits of their long labors at the Tudor Roar Before the Rolex 24 test days at Daytona International Speedway, Jan. 9–11, where the car went from back of the GT field to being just off the pace of the quickest Prototypes. (see Related Article: Tristan Nunez, SpeedSource Mazda Ready to Reach for Race Wins Again)
Mazda Motorsports Director John Doonan and SpeedSource owner/driver Sylvain Tremblay discussed the new performance at a press event at the Roar on Friday, Jan. 9. Doonan was not afraid to be court hyperbole in his choice of words—and the numbers supported him.
“One year ago on this particular weekend there weren’t many smiling faces in the garage area around this program,” he began. “But yesterday [I was saying] words like remarkable, words like miracle ... we’re talking about 20 mph in straight-line gained, six to seven seconds lap time ... at this particular track which isn’t necessarily a place where that allows us to show the strength of this engine in a straight line. We are doings exactly what we set out to do—the first time anyone’s taken a road-going diesel engine and asked it to do three times what it was designed to do.
