Ilmor Engineering has developed an innovative 130bhp, 700cc, three-cylinder, five-stroke petrol engine that develops the fuel economy of a diesel engine without any of the emissions shortcomings.
The engineering firm, which has a long history working in motorsport and which was previously part-owned by Mercedes when it prepared its F1 engines, has developed the radical road car engine to showcase its engineering ability.
The novel design allows the turbocharged engine to achieve a diesel-like expansion ratio on spark ignition, greatly improving fuel consumption but still achieving 122lb ft of torque.
Ilmor says the fuel consumption is better than the latest downsized turbocharged engines on sale. It estimates its engine is at least five per cent more efficient than an equivalent direct injection engine, despite currently running with multi-point injection.
The engine uses two fired four-stroke cylinders under high pressure, which alternately exhaust into a low-pressure central expansion cylinder, which, in a fifth stroke, provides a further expansion process on the exhaust gases.