25 September 2009
The powerplant of the Reno Unlimited Class racer Rare Bear is quite different from that of the standard Grumman F8F Bearcat. The Rare Bear has had the standard Pratt & Whitney R-2800 engine replaced with a larger Wright R-3350 radial engine. Unlike the tempermental R-3350s that were used on the B-29 Superfortress, Rare Bear's engine utilized parts from R-3350s that were ruggedized for airline use- but since those engines were too heavy for air racing, only the parts that were absolutely necessary were used.
The supercharger was also customized using one from a Lockheed EC-121 Constellation as a basis. Since the Constellation's supercharger was designed for direct-head fuel injection, it wasn't compatible with the Rare Bear's engine, so it was modified to work with the Rare Bear's pressure carburetion system.
A stock R-3350 generates 2800 horsepower at 2600 rpm with 45 inches of manifold pressure. The modifications to the Rare Bear's engine gives it's R-3350 4000 horsepower at 3200 rpm and 80 inches of manifold pressure.
Source: Air & Space Smithsonian, November 2009. "The Bear is Back- Can an air racing legend win again at Reno?" by Preston Lerner, p45-46.