Scuderi Air-Hybrid Engine Could Offer Big MPG Gains

We've all heard of the common Diesel and Otto cycles for internal combustion engines, and perhaps the Miller and Atkinson cycles that have made their way to advanced production and concept hybrid vehicles. These thermodynamic cycles describe the operation of reciprocating piston engines. Less known is the Scuderi Cycle, named after its inventor Carmelo Scuderi, a first generation American engineer who, after retiring in 1994, invented the Scuderi Split-Cycle Engine concept.

It is called a Split-Cycle because the four strokes of a four-cycle engine are done by two paired pistons - intake/compression and power/exhaust. A crossover passage transfers compressed air from the intake/compression cylinder to the power/exhaust one. Fuel is injected and fired to produce the power stroke. Unlike a four-stroke engine that fires every other revolution, the Scuderi engine fires on every crankshaft revolution like a two cycle engine. It still has four separate strokes so it doesn't have the disadvantages of two-stroke engines.

In a four-cycle engine, on the intake stroke of the piston, the piston moves from the top of the cylinder to the bottom while the fuel/air mixture is forced into the cylinder. On the compression stroke, the piston moves upward to compress the mixture. When the piston reaches the top of its stroke, the mixture is ignited and the pressure resulting from combustion forces the piston downward on the power stroke to produce power. As the piston moves upward on the exhaust stroke, the products of combustion are forced out of the cylinder. A two-stroke engine works differently by combining the intake and power strokes and also exhausting combustion products during this combined intake/power stroke.

The Scuderi engine features firing after