By Jim Roberts
It’s not every day you get to see and hear an aircraft engine that helped win World War II. Thanks to four dedicated volunteers, a 12-cylinder liquid-cooled Allison V-1710 engine is singing out loud near EAA Warbirds in Review.
During WWII, over 69,000 of the 1,500-hp engines powered aircraft as diverse as the Bell P-39 Airacobra, Curtiss P-40 Warhawk, Lockheed P-38 Lightning, North American P-51 Mustang, and North American F-82 Twin Mustang. Except for engines still in service, few examples remain of a stand-alone powerplant.
The story begins in 2022, when EAA Aircraft Maintenance Manager John Hopkins found himself with a recently overhauled V-1710 that had been removed from a replica Spitfire on display in EAA’s Eagle Hangar. Enter four volunteers: Paul Adams, Bruce Grumstrup, Charlie Tejchma, and Bob Viltz. The four were veterans of EAA’s B-25 Berlin Express restoration, and John asked them to create an operating Allison engine display. Though the powerplant only had a few hours since overhaul, crafting the stand to hold coolant, oil, gas, plumbing, and the wiring to make it run was a daunting task.
To make it a reality, Bruce Grumstrup said the team worked nearly 500 hours over two years. Charlie Tejchma recalled, “Plumbing the thing was a challenge. You didn’t have a drawing of what’s this tube do? … What’s that thing do? So we had to do a fair amount of research.”
Paul Adams described crafting the 24 exhaust stacks (two per cylinder) that give the Allison it’s throaty roar: “We could have bought the pipes for $640 apiece, but that wasn’t in the budget. So my son, who’s an EAA member, made a drawing for the gaskets, and we know a person who made the flanges and donated them, and we found a guy in Oshkosh who donated the steel tubes. So I made a jig and Bruce welded them, and we made the pipes for zero dollars.”
When the engine ran for the first time, Bruce said, “It was really exciting.” Charlie recalled, “We were worried about the torque, so we had it strapped down between two airplane tugs. We weren’t sure if it was gonna flop around, but it went fine. Now we just run it with outriggers on the stand, and people stand around watching it make its music.”
Paul Adams added, “In case you’re wondering, we’re gonna keep doing this. There’s a Pratt & Whitney R-4360 that’s our next project.”