Stroke of genius for gasoline downsizing
A new type of car engine which can switch automatically between a two-stroke and a four-stroke system promises to cut fuel consumption by more than a quarter.
Researchers at Brighton, led by Ricardo Professor of Automative Engineering, Morgan Heikal, are working on the 2/4Car, which will cut the amount of petrol that premium cars use by 27 per cent, and reduce their carbon dioxide emissions too.
The car has a revolutionary new engine system which allows it to kick into two-stroke mode when the driver accelerates quickly, but go back into four-stroke mode when the car stops speeding up.
Two-stroke petrol engines can produce more power for their size than four-stroke engines, and are often used in chainsaws and small motorcycles, but their simple designs cannot meet the durability or pollution control requirements necessary for a car.
But the 2/4Car gives the driver the best of both worlds – the acceleration of a two-stroke engine for brief periods when it is needed, and the reliable drive of the four-stroke for the rest of the time.
The engine uses what is called a top-entry inlet port system which mostly eliminates the durability and pollution control problems. This system was designed and patented by Ricardo plc, the leading independent technology provider and strategic consultant to the vehicle industry, with UK headquarters in Shoreham-by-Sea. Ricardo and the university have close links.
Its group technology director, and visiting professor at the University of Brighton, Neville Jackson, said that an initial concept study has shown the capability of the system and a prototype of the engine had already been successfully made during the second stage of the project. The third stage was a two-year project that began in September 2008 to place the engine in a functional car.
"Because the two-stroke mode is so much more powerful than the four-stroke, we can get the same performance out of two-litre engine using our system than we can out of an ordinary fourlitre engine that you find in premium cars," he said. "That means that the amount of fuel used is less and so is the pollution."
"The engine will be relatively expensive and is therefore more suitable for larger, more expensive cars, so this is the market we are aiming at, and the latest stage of the project aims at putting the engine into a working Jaguar XF."
"We've had a lot of interest from car firms so we know that if we succeed there’s a good chance the engine could become a real option for more fuel efficient vehicles."
He said the project had been initially part funded by the UK Foresight Vehicle programme using government financing, and also by the then Department of Trade and Industry and more recently the Technology Strategy Board.
A two-stroke engine is so called because it only takes two strokes of the piston to draw in air, compress and burn the fuel to produce work and then expel the exhaust gases. A fourstroke engine takes twice as long to complete the process, separating the intake of air, compression, combustion and exhaust into four separate up or down strokes of the piston.
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