Higher Octane Not Always The Answer To Knocks
*» Chemists of the Department of Scientific and Industrial Research in the petroleum and oil laboratory of the Dominion Laboratory analyse fuel and lubricating oils, and assess their suitability to New Zealand conditions. They check the various grades of imported petroleum to see that they are up to the specifications, and full data are kept of the recommended fuels for the many types of internal combustion engines.
The suitability of “benzine” for the motorists of this country, said Mr J. B. Hyatt of the Dominion Laboratory, can only be a very general classification, since the fuel, to give the most efficiency depends not only on the design of the engine, its condition, and the amount of wear that has taken place, but on the weaker conditions, on the adjustment of the spark, carburettor, etc., on the load, and on the speed of the engine. Some motorists think that given a high octane fuel the performance of their engines will be better, but the suitability of the octane number of a fuel can only be measured by the tendency of the engine to knock (“pink”) under a given set of’ conditions.
Improvement of the fuel beyond the point necessary to eliminate knock involves unnecessary expense and, will not improve performance. Considerable carbon accumulations in the combustion chamber will cause knock, and severe knock may damage pistons and bearings as well as causing loss of power, but a mild knock has no measurable effect on the performance of the engine.
The demand for economical cars with excellent performance has led to an increase in the compression ratio of engines, and thence to a higher octane number in petroleum. The limited brands on the market will give satisfactory performance for practically all cars, and when excessive knocking under normal driving takes place it generally shows the need for de-coking or adjustment of carburettor or ignition. The check on the specification of motor fuels by the Dominion Laboratory helps to set a standard that will give the motorist, as far as possible, an efficient fuel. -
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Bay of Plenty Beacon, Volume 13, Issue 71, 30 March 1949, Page 6
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348Higher Octane Not Always The Answer To Knocks Bay of Plenty Beacon, Volume 13, Issue 71, 30 March 1949, Page 6
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