Wright Aeronautical R-3350-57 Cyclone 18
The R-3350-57 is the engine model in the B-29 flown by Colonel Paul Tibbets in 1945. The engine differs from the earlier R-3350-23 in that it uses fuel-injection.
Each row of nine cylinders has its own fuel-injection pump. A balance bar connects the two pumps to ensure the same fuel-air mixture enter each row of cylinders.
The front and back rows of cylinders exhaust into separate turbochargers mounted on the nacelle to drive the intake air though an intercooler before entering the intake manifold.
This engine was mounted on the B-29 when it was in the outdoor storage yard and was ripped off the airplane during the 1979 tornado disaster. The engine is on displayv in the B-29 Hangar.