HIGH COMPRESSION.

Auckland Star, Volume LXIV, Issue 245, 17 October 1933, Page 15

HIGH COMPRESSION.

ETTECT ON PERFORMANCE. BETTER GETAWAY CLAIMED. One of the major advantages gained by tho buyer of tho latest models of motor cars is the greater efficiency and economy obtained as the result of the modern engine having in most instances a higher engine compression ratio than did earlier models. Possibly many motorists do not fully appreciate what a dilFercnce higher compreseion makes in the power output of a petrol engine. Experiments conducted oversea, with a small eight-cylinder engined car, with a 5.2 compression, and then later with a 7.1 ratio, proved that with tho lower compression the acceleration from 5 to 45 m.p.h. was accomplished in 18.2 seconds, while with the higher ratio in use, the time taken was only 14 seconds. The difference of 4.2 seconds may appear insignificant, but it represents many car lengths in the getaway of a car, say, ill city traffic stops.

In hill climbing, the higher comprcssioned engine also gave better results. Testing out a car with alternative ratios of 4.77 to 1 and 5.65 to 1, it was demonstrated that on an 11.6 per cent grada tho lower compressioned car suffered a decrease ill epeed, which would have necessitated a gear change on a longer hill, while the higher ratioed engine maintained a high speed and romped up on top gear.