With an eye on challenging the Lycoming turbine engines that have dominated Unlimited Hydroplane racing since the ’80s, Aardema Development is designing a new V12 engine with kinship to the legendary Allison engines that used to rule that class.
“A lot of inspiration came from the Allison V12,” says Kevin Braun, who along with Pete Aardema, Jeff Johnson and Kevin Aylesworth are leading the design efforts of the V1200 engine. “But we’ll do it with new technology.”
More views of the Aardema V12
Like the Allison, the engine is based on a 60-degree V overhead-cam architecture and will feature twin superchargers. Unlike the Allison, the Aardema V1200 will have a 3-valve instead of a 4-valve head design, two spark plugs per cylinder and modern electronic fuel injection.
Other Aardema overhead-cam conversions have featured 3-valve heads, so the airflow and valvetrain dynamics are familiar to the team.
“While it’s originally designed for Unlimited Hydroplane, it could be adapted to truck pullers or offshore boat racing,” adds Braun, who was showing off the first prototype at the recent PRI show.
The Allison featured an undersquare 5.5 x 6 cylinder for a total displacement of 1,710ci. Currently only one team is using the Allison V12 on the hydroplane circuit as the majority of boats utilize a version of the Lycoming T-55 turbine. The Aardema team wants more rev potential than the Allison, so the V1200 goes oversquare to help improve rev potential with a 5.625-inch bore and 4-inch stroke for 1,193ci.
“The Allison was limited to around 4,000 rpm,” says Braun. “We’re looking at 6,800 rpm redline.”
Views of selected internal parts and the twin Vortech superchargers.
Work on the engine started in October 2014. The crankcase is a multi-piece design that is cut from aluminum plate, welded and heat treated before machining. Custom parts include a Scat billet crankshaft, Arias pistons, R&R Racing connecting rods, Elgin camshafts, Darton cylinder sleeves, Dailey Engineering dry-sump oil pump, ARP fasteners, Cometic head gasket and BHJ balancer. Compression ratio is 8.5:1, and max valve lift is expected around .750-inch.
The 3-valve head (two intake, single exhaust) will sport titanium valves and custom shaft-mounted roller rockers built with parts from Crower and Jesel. EFI West helped build the fuel system that includes two 90-pound injectors per cylinder and a PE3 ECU. Providing up to 15 pounds of boost through the custom intake system will a pair of Vortech superchargers.
The team is hoping for an initial dyno test of their V12 in early 2016 with goals of making more than 3,000 horsepower.
Only one team is currently using the Allison V12 in hydroplane racing. Check out the link in the story to learn more.