Two-cylinders. One 2-71 GMC roots blower. A single Hilborn fuel injector. One magneto. Some nitromethane, and a dynamometer. The resulting 257-horsepower engine shown here was created by taking an already halved Pontiac Tempest four-cylinder engine and halving it again. The cylinder head and block were sealed off by aluminum plates after their appointment with the band saw. Thompson bolted up the Twin-Tempest into a non-streamlined Dragmaster chassis, and chased 1961 National and International records for Class F 61-91-cu.in. engine group, reporting a redline of 8,500 RPM on one of the runs. The car ran an average 106 miles per hour on the standing mile. Mickey Thompson engine builder Fritz Voigt told us that the sprung plate on the intake manifold featured an o-ring made of nitromethane-resistant material. The springs were set to release boost at a certain pressure. The material was tough enough to reseal if an overboosted plate hopped around, and keep the engine on its charge without windowing the block.
Special thanks to the Wally Parks NHRA Motorsports Museum.