Van Overbeek powers his 911 with a European-spec 3.0-liter flat six. With TWM individual throttle bodies, a standalone MoTec engine-management system, headers, and a free-flow exhaust, the SC powerplant produces approximately 255 horsepower at the crank. Those ponies are sent to the rear wheels via a stock 915 transaxle with a Wevo shifter and an aggressive limited-slip differential.
The Spec 911’s front suspension consists of factory A-arms with raised spindles, Bilstein struts, and slotted camber plates. In the rear, reconditioned trailing arms partner with custom Wevo spring plates. “Hayden Burvill at Wevo designed a one-off set of spring plates that eliminates the maddening camber and toe adjustment eccentric bolts,” says van Overbeek. “With Hayden’s design, you just loosen the bolts between the trailing arms and spring plates and turn a screw.”
Smart Racing Products anti-roll bars are fitted front and rear, but the rest of the suspension setup, including the size of the torsion bars, remains confidential…although the owner suggests a bottle of his favorite wine might be enough to pry a few class-legal secrets out of him!
Van Overbeek has updated the Porsche’s braking system a few times over the years. He began with early 930 stoppers, changed to Boxster brakes, and now uses an AP Racing setup with dual master cylinders and driver-adjustable brake bias designed by Craig Watkins (formerly the Chief Engineer at Flying Lizard Motorsports, Johannes’ old team). According to van Overbeek, the street-car calipers couldn’t handle the heat of competition; at maximum temperatures their pistons would stick slightly, making brake modulation very difficult. He has no such complaints with the AP system.
The Porsche currently rolls on 16-inch cast-aluminum Braid wheels, which mimic the look of the legendary Fuchs units without the concern of using a decades-old wheel in competition. The Braids are wrapped in Toyo RA1 R-compound rubber: 225/50-16 up front and 245/45-16 out back.
When asked what makes a successful Spec 911 racer, van Overbeek replies, “Car preparation is the absolute key.” (He’s not the only one who thinks so; his car was honored with the series’ Best Prepared award in 2013.) This means the Porsche gets rebuilt every other year, and each time it gets a little better. This year, van Overbeek finally broke down and added a MoTec data-acquisition system and dash display. Impressively, the engine has required only one major rebuild during seven racing seasons.
The Spec 911 series has been a very special place for van Overbeek. “The combination of the car, the racing, and the people have made Spec 911 the most enjoyable experience I have had in almost 40 years of driving race cars,” he says. He expects to continue racing regularly for the years to come, and his trusty Porsche will continue to evolve and receive the TLC it requires to run at, or near, the top of the field. That’s enough to make it “the definitive Spec 911” in my book.