The Scuderi Split Cycle Engine design is a rethink of the conventional four-stroke Otto cycle internal combustion engine conceived by Carmelo J. Scuderi (1925-2002). While as of this writing no working prototype of the engine exists, computer simulations carried out by the Scuderi Group and the Southwest Research Institute showed promising gains in efficiency and toxic emissions. It also has the innate capacity to power an air hybrid system.
n a conventional Otto-cycle engine, each cylinder performs four strokes per cycle: intake, compression, power, and exhaust. This means that two revolutions of the crankshaft are required for each power stroke. The Scuderi split-cycle engine divides these four strokes between two paired cylinders: one for intake/compression and another for power/exhaust. Compressed air is transfered from the compression cylinder to the power cylinder through a crossover passage. Fuel is then injected and fired to produce the power stroke. Because the engine produces one power stroke per crankshaft rotation, a Scuderi-cycle engine has the same total engine size (number of cylinders and displacement) as a comparable Otto-cycle engine.
The power cylinder fires just after the piston has begun its downward motion (after top dead center, or ATC). This is in contrast to engine design convention, which calls for combustion just before top dead center (BTC) in order to allow combustion pressure to build. The Scuderi-cycle engine can get away with firing ATC because its burn rate is faster, and so is able to build pressure more quickly. This property of firing ATC is a key feature of the design, as it enables the engine's higher efficiency and lower emissions.