Ilmor Engineering Creates a 5-Stroke Engine

In the quest for fuel efficiency, most companies are looking at hybrid-electric vehicles. British engineering firm Ilmor, known for producing racing engines, came up with a different solution.

Ilmor Engineering’s solution for greater fuel efficiency was to create a 5-stroke gasoline-powered engine with the efficiency of a diesel, but without the usual emissions byproducts. The firm produced a turbocharged 3-cylinder that achieves a 10 percent increase in fuel economy over a conventional 4-stroke engine as proof of concept.

The engine operates by using low- and high-pressure cylinders and a similar setup for the camshafts. The two high-pressure cylinders operate as a conventional 4-stroke engine does and alternately exhaust into the third, low-pressure cylinder, where the burnt gases perform more work. More is also gained in the low-pressure cylinder because its compression and expansions ratios aren’t fixed, allowing the cylinder to selectively choose the optimum expansion ratio.

The idea of the engine is that there is more work done by using the low-pressure cylinder for the same amount of gas that would be burned in a conventional 4-stroke engine. Also, unlike some fuel saving technologies currently being researched, the 5-stroke engine would not be terribly expensive to produce, as it uses parts and materials already in use.

The proof of concept engine is a 0.7-liter turbocharged unit producing 130 hp and 122 lb-ft of torque. Ilmor hopes to begin testing the engines in vehicles shortly and aims to cut consumption by 20 percent when compared to a conventional 4-stroke gasoline engine.

Source: Ilmor Engineering