Speed Demon: The world’s fastest piston engine, wheel driven car


Four hundred miles per hour is typically jet engine territory. After all, a Boeing 737 cruises at 485 mph. It seems ludicrous that any ground vehicle with a piston engine sending power to the wheels could exceed the 400 mph barrier. Only a handful of vehicles have achieved this feat. With a record smashing average speed over one mile of 439.024 mph (and a top speed of 462 mph) the Speed Demon is the fastest piston engine wheel-driven car of them all – and it uses Turbosmart blow-off valves in an unbelievable way.

Last year, a shock crash at nearly 400 mph on the Bonneville Salt Flats destroyed the car, but miraculously left driver George Poteet without any serious injuries. A testament to the strength of the Speed Demon’s engineering, Poteet walked away from that crash – literally walked – with barely a scratch.

The car, however, was predictably a wreck. The record-breaking car is now undergoing a rebuild to cement its place in the record books for years to come. Poteet and co-creator Ron Main have gone back to the drawing board with a new engine and refined design, with the aim to go even faster.

Five hundred miles per hour is the new target. That’s a speed that would beat any wheel driven land speed record, including turbine-engined efforts.

Powering the Speed Demon to that new target is a 368ci (6.0-liter) twin-turbocharged Small Block Chevy V8. The Small Block was chosen for its compact size, as it needs to fit within the Demon’s narrow chassis, which was originally designed to house a four-cylinder engine. Three injectors per cylinder make sure the engine’s hefty thirst is quenched, while a Liberty air powered seven-speed transmission gets the SBC’s two-thousand-plus horsepower grunt to the wheels.

Since the engine only runs for a few minutes at a time, the Speed Demon crew do not run a conventional cooling system with a radiator. Instead, there is a single aluminum tank filled with 14 gallons of chilled water, which provides all the engine’s cooling needs. However, the team had experienced problems with the set up. If the engine blows a head gasket (and in this kind of racing, it often does), the water tank was instantly pressurized to the point where it exploded.

Enter Turbosmart USA’s General Manager Marty Staggs, who came up with a novel use of two Big Bubba blow-off valves to solve this very serious problem. With the Bubbas mounted on the water tank, the valves will open when the pressure builds too high in the water tank and release it to where it is needed, such as at the cylinder heads. A pressure transducer on the tank talks to the car’s ECU, and when it senses 45psi or more, solenoids switch to remove the manifold pressure reference, and the blow-off valves open, releasing the excess pressure.

The Speed Demon is a testament to the never-give-up spirits of its creators, and the engineering brilliance of the team behind it. To get any land vehicle to this kind of speed takes a lot of skill. Turbosmart is immensely proud to be involved in providing technical assistance for such an exciting vehicle.


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