Ilmor Engineering Develops New 5 Stroke Automotive Engine

The quest for the ideal automotive engine has seen the evolution of the diesel engine, the hybrid and all manner of alternative electric battery operated solutions. The latest buzz is centered on hydrogen powered autos. Now a new spin on the old 4-stroke internal combustion engine may add another option to the mix.

Ilmor Engineering, best known for its design of racing engines for Honda, Mercedes-Benz and GM, has created a new 5-stroke automotive engine that could very well revolutionize the industry.

The new 700cc engine delivers 130 hp combined with exceptionally high gas mileage and very low emissions and can be produced using existing manufacturing technologies.

Ilmor Engineering engines have been under the hoods of 14 Indy 500 and 44 Formula 1 Grand Prix winning autos. Mercedes-Benz purchased Ilmor’s engine division, which currently provides research and development services focused on migrating advances in its racing engine technologies to its consumer focused models.

The company’s patented 5-stroke engine is currently being displayed at automotive trade shows. Engineers have their sights set on developing the engine to deliver fuel economies and emission levels comparable to current diesel engines without the associated problems. Mercedes-Benz offers a wide array of diesel-powered autos including a number of luxury models. However, diesel technologies in use today suffer from high particulate and nitrogen oxide (NOx) emissions compared to gasoline engines and are considered by many to be environmentally unfriendly.

The new 5-stroke engine uses two alternately exhausting, high pressure fired cylinders which work on a traditional 4-stroke cycle. The cylinders in turn displace exhaust into a single low pressure cylinder which extracts the burnt gases further. The low pressure cylinder separates the processes of expansion and compression to facilitate optimal expansion ration which is independently selected from the compression ratio. Overall expansion ratios currently approach those of conventional diesel engines at around 14.5:1.

The engine utilizes two overhead camshafts and a conventional valve spring mechanism. The low pressure camshaft runs at full crank speed while the high pressure camshaft is limited to half that speed. The 5-stroke concept engine is also turbocharged to deliver higher output. The design allows the low compression cylinder to take on a greater percentage of the work load at the first onset of engine knock.

In tests, the engine has delivered impressive fuel efficiency results over a wide range of operating conditions.

The Ilmor research and design division anticipates deploying a version of the new 5-stroke engine in a production model offering 150 hp while weighing up to 20% less than a comparable, conventional gasoline engine.

According to Ilmor’s engineering manager, Steve O’Connor, the company is, “Looking for a manufacturer to back the idea, and the interest centers on its use in a hybrid application, as they tend to need sudden bursts of energy, and that is what this engine does well.”

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