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.
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