CLEAN AIR

Evening Post, Volume CXIII, Issue 54, 5 March 1927, Page 24

CLEAN AIR

ENHANCED ENGINE LIFE

Experienced' motorists admit the adrisableness, 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 can be kept out of the cylinders a marked difference in the period of service which will be obtained from the ear without the necessity for overhauls, engine cleaning, and valve grinding may be expected. A number of leading- makes of cars particularly the best grade American makes, now fit an air 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 tho combustion chamber with tho gas. Once in tho combustion chamber this grit quickly mixes with the oil on the cylinder walls or piston head, and forms one of tho most objectionable abrasive compounds that could bo imagined scoring and wearing the cylinder walls and skirts of the pistons, and caking into a hard black mass which becomes incandescent and causes pro-ignition. Tho damage done to the cylinders is rapidj comparatively speaking, and has been calculated to increase wear at a rate of ns much as 17 times in the same mileage as on an engine effectively protected against such ravages. Cars run over a distance of 35,000 miles were tested by the manufacturers of one typo of air cleaner, and they state that they ooncluded that the cylinder walls of a car not fitted with tho air cleaner showed a wear on the average of 15----1000 inch at the top, 9-1000 in the middle, nnd i-1000 inch at tho bottom, as compared with 1-1000 inch at the top. the same in tho middle, and i-1000 inch at tho bottom, in tho caso of tho car protected against the dust. The piston rings showed a similar difference in comparative wear, while that of the piston skirts themsolves was just 12 times as great iv the case of thoso not protected in comparison with thoso that wero. The uneven wear, also on the cylinder walls, of course; would involve the car owner iv tho expensive necessity for reb"6ring tho cylinders and fitting new pistons much sooner than would be necessary otherwise.

In addition to theso drawbacks, tho dust sucked into tho engine finds its way into the crankcaso and lubricating oil, nnd is pumped to overy part of the cngino whero it has equally baneful effects. Motorists can form some idea of how much of this abrasive dust enters their engines if no air cleaner is fitted when it is stated that an ordinary four-cylinder car travelling at a speed of 20 miles an hour accumulates about one ounce of sand, dust, dirt, and grit every seven miles, according to the results of experiments. Tho.engine draws in. air. through tho carburettor at a velocity of more than a milo a minute, and. this air carries with it a large proportion of abrasive foreign matter. AVhcn this, statement is considered, it is a matter- for surprise that the engine does not accumulate more carbon than it docs.