It has been more than five years since a piston-powered unlimited hydroplane has raced full-time in competition. Now the Go3 Racing team of Ed Cooper is hitting the water again, much to the delight of fans that have made that U3 boat their favorite for its old-school approach to throwing those massive rooster tails.
Nicknamed the Big Red Turbonator, this Allison V12-powered boat will again challenge the Lycoming T-55 L-7 turbines–the same powerplant found in the Chinook helicopter–in a division that can provide some of the wildest thrills in motorsports. Unlimiteds are capable of speeds over 200 mph and are designed to slice through both air and water.

Top: The U3 unlimited hydroplane in action. Below: The engine runs on methanol but uses gasoline during startup. If the engine is hot, it can get a little angry while it’s being primed for a restart. All photos from Go3 Racing Facebook page. Bottom photo submitted by John Woodward.
EngineLabs was alerted to the boat’s return by the above video that shows the twin-turbos in action. Be sure to expand the video to full screen to see the water injection operation at the intake throat of the turbos.
We don’t know much about the actual engine setup and modifications. The team is on the road for a race in Washington this weekend. We hope to follow up soon and get the inside details on how the Allison was converted from a supercharged workhorse developed for WWII fighters into a twin-turbo beast for the water.
Various shots of the engine and the Go3 team in action. The shop reportedly has 12 fully prepped and race-ready engines for the season.
We do know that the 12-cylinder, 60-degree block originally boasted a displacement of 1,710ci with a 5.5-inch bore and 6.0-inch stroke. The engine was adapted into Unlimited Hydroplane racing in the ’40s and later dominated the division up through the ’90s until the turbines became the engine of choice. Some Allison engine builders reportedly surpassed 4,000 horsepower with their modifications.
Until we find out more, enjoy this video and head over to the Go3 Facebook page for the latest results and more photos recalling the boat’s unique history and its rebirth this summer.
Left: Closeup of the current configuration, but the team has experimented with a larger plenum.