Q I have heard that a device exists for ' 46 ' running

13th September 1968, Page 205

13th September 1968

Page 205

Page 205, 13th September 1968 — Q I have heard that a device exists for ' 46 ' running

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a petrol engine on open throttle and that this has a number of advantages. Can you give details?

A In a stratified-charge petrol engine, as N—a developed experimentally by MAN of Germany, the engine is run on open throttle and the fuel is injected into a special type of combustion chamber in the piston. The swirling action of the air in this chamber is such that the fuel mixes with the air in a stratum and the depth of the stratum increases progressively as the amount of fuel injected is increased. Until the engine is running under full load (when the stratum occupies the entire chamber), the fuel does not reach the air in the area on the far side of the stratum. The engine can, therefore, be run on full throttle.

Possibly the device that has been mentioned to you is one that enables the mixture of a conventional petrol engine to be throttled by varying the opening of the inlet valves. It is known that the General Motors Corporation of America has experimented with such a system and that good results are claimed. These include the ability of the engine to burn very lean mixtures which should improve the overall fuel consumption. Of possibly greater importance it should reduce atmospheric pollution.