How Belly Tank Racers Work

One of the literal shortcomings of some WWII fighter planes was their range. They simply couldn't hold enough gas for some of the missions they were required to fly. That's where drop tanks, or belly tanks, came in. Belly tanks were supplemental gas tanks. They'd be strapped to the belly of the plane to provide extra fuel, which in turn provided additional flying range. When the tank was empty, the pilot would simply jettison it.

And while this military hardware was built for a specific purpose, it turns out that those belly tanks are very good at something entirely different. Belly tanks make great race cars, especially if you're trying to set a land speed record on a dry lake bed. And not surprisingly, their preferred racing locale is also how belly tank racers got their other name: lakesters.

The original purpose of a belly tank helped make it ideally suited for use as a race car body. If you're strapping something the to the belly of a plane to increase its flying range, the last thing you want to do is have a negative impact on how far the plane can fly. That is, you don't want to add so much wind resistance that you end up burning more fuel by carrying the belly tank than the tank itself can hold. In order to minimize wind resistance and maximize fuel economy, belly tanks had to be very aerodynamic. Belly tanks look like giant bullets and are about as aerodynamic as they come.

After World War II ended, belly tanks ended up in surplus and scrap yards. Hot rodders took notice. Beyond the belly tank's super-fast shape, car builders noticed that the rear of the belly tank was just wide enough to install a car engine block and rear end. Given that hot rodders were already building and racing their own creations made from a hodgepodge of car parts, adding an airplane fuel tank wasn't that farfetched — especially when the surplus tanks could be bought for about $35 [sources: Wise; Wilkinson].

If you're driving around in an old gas tank, you shouldn't expect a lot of creature comforts, which is good, because belly tank racers don't provide any. In a belly tank racer, the driver sits in a tiny compartment about midway in the tank. Slight holes are cut in the tanks for drivers to poke their heads out. Some belly tank racers have bubbles or cages that go over the driver's head, but many don't. Lakesters also usually don't have windshields, so pack your racing goggles and be prepared to get a lot of sand in your teeth [source: Wise].

The first belly tank racers used a front engine design, where the engine sat in front of the driver. They used this setup mainly because the first belly tanks they used were 165-gallon (625-liter) tanks from P-51 Mustangs. When racers made the switch to larger 315-gallon (1,192-liter) tanks taken from P-38 Lightning planes, there was room to put the engine behind the driver, and that's how most belly tankers and lakesters were laid out from then on. The type of engine varies, but for most belly racers, the bigger the engine, the better. Classic belly tank racers had American-made engines because of their availability to hot rodders at the time. Record-setting engines for belly tank racers include Ford, Mercury and Chrysler V-8s [source: Wilkinson].

Because of the tight confines of a belly tank racer, the wheels aren't under the body of the car. Rather, they stick out to the sides in the front and rear. While it may look a little goofy, it gives the racer more stability than affixing the wheels under the car's very narrow body. Stability is important, because unlike modern race cars, belly tank racers don't have spoilers [source: Wilkinson]. In engineering, spoilers aren't just what you see on message boards (i.e., "spoiler alert: Snape kills Dumbledore"), they're wings on the backs of cars. When a car is driven at high speeds, it will start to lift slightly off the ground. A spoiler forces the car back down to firm contact with the ground. Belly tank racers don't have spoilers, and because of the speed at which they travel, plus their light weight, a bad bump or cross breeze could send them airborne.

Got a spare fuel tank and an itch to build a fast car? Keep reading — today's lakesters have some big shoes to fill.

Aside from a fast car, the one thing you need to set land speed records is space. Across California, Nevada and Utah are the dry beds of giant prehistoric lakes. These salty, wide-open expanses are flat and smooth. In other words, they're perfect for top-speed runs, which is why hot rodders have been using them since the 1930s. Today's cars have gone over 600 miles per hour (966 kilometers per hour) on the Bonneville salt flats, a rock-hard lake bed in Utah that's synonymous with speed trials and fast cars [sources: Christensen; Wise].

To set an official record, during the official Speed Week at Bonneville, for example, each car is given two runs through the course. The average speed from those two runs is used to determine the final speed for the car [source: Wise].

One of the most famous belly tank racers is associated with Alex Xydias and his iconic So-Cal Speed shop. Built from the belly tank of a P-38 Lightning and powered by a 156-cubic inch (396-cubic centimeter) V-8, the So-Cal Speed Shop belly racer ran at an average speed of 145 miles per hour (233 kilometers per hour) at Bonneville in 1951. Later, So-Cal swapped out the engine for a larger one and averaged 181 miles per hour (291 kilometers per hour) with the new rig. They swapped the engine out yet again (because if it worked once, why not try it again?) and managed to average 195 miles per hour (314 kilometers per hour) [source: Barracuda Magazine].

Other classic belly racers include the one from Mal Hoopster, which broke the So-Cal Speed Shop record with a Chrysler-powered belly tank racer that averaged 197 miles per hour (317 kilometers per hour). Bill Burke, a hot rodder who worked at So-Cal Speed Shop and is widely credited with first noticing that belly tanks would make great race cars, built a belly tank racer that made it up to 131 miles per hour (211 kilometers per hour) [source: Barracuda Magazine].

A classic belly tank racer from the 1940s and 50s would be expensive to buy today, so you're not likely to see them at the racetrack. The So-Cal belly racer that made it up to 195 miles per hour (314 kilometers per hour) is worth nearly $200,000 today [source: Wilkinson]. But if you don't have that kind of cash to spare, you can always head out to Speed Week at Bonneville in August and see the heirs of the belly tank racer's legacy hit speeds the original models could only dream of.