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Today, there is only one piston-powered unlimited hydroplane — Ed Cooper's U-3. It uses a turbocharged Allison engine developed for World War II fighter planes. The U-3 team builds most of its own engines, but it is estimated an engine like the one in the U-3 would cost $70,000-$80,000 to buy new. Allison engines run on methanol fuel and burn much more than a turbine. The U-3 burns 18 gallons of methanol a minute while the turbine burns 4.3 gallons of kerosene a minute. Allisons became widely used in power boats shortly after WWII — the first victory by a hydroplane using an Allison engine came in 1946 by the Miss Great Lakes in Washington, D.C. Along with the Rolls-Royce Griffins, they were the engine of choice from the 1950s through the mid-1980s. Their main disadvantage is their lack of dependability, largely because of all the parts involved. They are prone to breaking down. Also, since the piston engines are heavier, boats using them don't accelerate as well out of turns.
Most of the turbine engines used by hydroplanes are Lycoming T-55 L-7 from Chinook helicopters built for the Vietnam War. There are said to be about 840 of them available, and they can be purchased for roughly $50,000. The biggest reason they became the motor of choice among hydroplane owners is their dependability. They have fewer parts than a piston engine, and many of the parts are welded together. One owner said he has used the same three engines for the past five years. They also weigh about half as much as piston engines, coming in at around 900 pounds. Turbine engines run on kerosene fuel and need much less than piston engines, saving on expense and weight of the boat. A turbine was first used in a hydroplane competitively in 1974. The first victory by a turbine boat came in the Pay 'N Pak in 1982 in Syracuse, N.Y. By the mid-1980s, they were being used regularly. Since the early 1990s, all but one boat has used turbine engines.