Radial-engine, Prop-driven VW Headed to Bonneville

One of the worst trends in the current automotive market is the engine cover. Open the hood of any performance car, and all you see is plastic.

Mike Niemans, however, goes with the full Monty attitude and hangs the entire engine off the tail end of a Volkswagen Type 1. No phony cover. Not even a bonnet. Just seven cylinders in all of their naked glory.

In the video above, a tank clutch hub was used on the prop shaft for initial setup purposes. The car now has a 4-foot diameter prop for motivation.

If that’s not enough to draw attention to the matte-toned Bug, there’s also a 4-foot propeller.

“Yeah, it brings in crowds of people,” admits Niemans, who owns a motorcycle shop in Northern California.

Prop-driven cars never had a real chance with the mass consumer market, but none of the previous attempts ever looked as cool as this Beetle, with its 11-liter radial tank engine mounted in place of the rear bumper.

Built by Continental, the W670-9A engine is rated at 220 horsepower. The engine was used in a variety of applications, and this 1941 model was pulled from an M2 tank. Bore is 5.125 inches with a 4.625-inch stroke, giving the engine total displacement of 668ci.

“The tank engines had backside drives,” explains Niemans. “The airplane engines didn’t. There’s an auxiliary drive on the back that spins twice as a fast as the front prop.”

At first, Niemans considered adapting a hydraulic pump that would drive the flywheel on the stock transmission. 

The engine weighs 540 pounds and is powered by propane. The black reservoir next to the propane tank is for 80-weight oil.

“That is a power source if I ever needed anything to run the tranny,” says Niemans. “But after putting on the prop, it’s got so much power that when I give it gas, it’ll go down the runway just like a plane taking off.”

The 2-blade reverse-pitch prop is normally used in the nearby vineyards to prevent crop loss during frost spells. Niemans bored out the hub and mounted it to the engine’s prop shaft. In the startup video above, Niemans uses the clutch hub from the tank in place of the prop.

“I just used the clutch hub to dial in the engine,” says Niemans.

Powered by propane

The engine weighs just under 550 pounds. Hanging weight that far behind the rear wheels, one would expect the need for wheelie bars. Niemans does have a few bags of cement resting in the front boot.

“Even without the cement, a bunch of us couldn’t lift up the front end,” claims Niemans.

The engine runs on propane. Again, taking a cue from the wind generators in vineyards, Niemans converted the radial’s Strombergs to run on the light fuel. 

“It runs great on propane,” explains Niemans. “I don’t need any fuel pumps, just a bottle of propane.”

To say that Niemans is a radial-engine affectionadio would be quite the understatement. He has them everywhere in his shop. And while most people have rose bushes or bird feeders in their front yards, Niemans has five different radial engines from as far back as the ‘20s and ‘30s standing guard. His house is just across the tracks that carry the famous Wine Train through Napa Valley, and he’ll put on a show for the passengers by starting up five of them at once (see video below).

Light aircraft need about 100 to 120mph runway speed to take off. Just how fast could a prop-driven car go? We found one car from the mid-’30s that went 85mph. Niemans, who was inspired by the movie “World’s Fastest Indian,” is planning a trip to Bonneville to see what speeds his VW will reach flying across the salt flats. He will need different tires, a proper rollcage and other safety items, but he envisions some interesting scenarios. First, he has an air foil off a local sprint car to hold the front end down. He could add nitrous, if he needs a little more power. Right now the engine is set to max out at 2,500 rpm. He also has access to variable-pitch props.

“I can do all sorts of different stuff,” he says. “We’re just going to take it up to Bonneville, put the prop on, let her go and see what happens!”


About the author

Mike Magda

Mike Magda is a veteran automotive writer with credits in publications such as Racecar Engineering, Hot Rod, Engine Technology International, Motor Trend, Automobile, Automotive Testing Technology and Professional Motorsport World. He was the editor of four national automotive magazines, including Chevy High Performance, and has authored hundreds of automotive technical briefings. In covering nearly every type of motorsport, Mike has collaborated with many of racing's top engine builders and factory engineers.
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