CLEAN AIR.

Putaruru Press, Volume VI, Issue 233, 19 April 1928, Page 7

CLEAN AIR.

ENHANCED ENGINE LIFE. Experienced motorists admit the advisability, even if they do not put their belief into practice, of fitting some device for ensuring that the supply of air to the carburettor shall be as pure and clean as possible. The greater portion of the carbon, which has such a deleterious effect upon the running of the poppet valve type of internal combustion engine, has been found on analysis to consist of a very large proportion of road dust and grit, and if this is kept out of the cylinders a marked difference in the period of service which will be obtained from the car without the necessity for overhauls, enginecleaning and valve-grinding may be expected.

A number of leading makes of cars, particularly the best-grade American makes, now fit an electric cleaning device to their carburettors, the fitting being attached to the air intake on the carburettor in place of the more usual dome-shaped cap which is more decorative than effective in preventing dust and grit from being sucked into the induction pipe and carried into the combustion chamber with the gas. Once in the combustion chamber this grit quickly mixes with the oil on the cylinder walls or piston head and forms one of the most objectionable abrasive compounds that could be imagined, scoring and wearing the cylinder walls and skirts of the pistons and caking into a hard black mass which becomes incandescent and causes pre-ignition. The damage done to the cylinders is rapid, comparatively speaking, and has been calculated to increase wear at a rate of as much as 17 times in the same mileage as on an engine effectively protected against such ravages. Cars run over a distance of 25,000 miles were tested by the manufacturers of one type of air cleaner, and they state that they concluded that the cylinder walls of a car not fitted with the air cleaner showed a wear on the average of 15/1000in at the top, 9/1000in in the middle and 1/1000: :i at the bottom, in the case of the car protected against the dust. The piston rings showed a similar difference in comparative wear, while that of the piston skirts themselves was just 12 times as great as in the other case.