“EXTRA AIR”

Shannon News, 31 July 1928, Page 4

“EXTRA AIR”

THE USE OF SPECIAL DEVICES,

DO THEY TEND TO WARP THE

VALVES?

A question frequently raised is whether the use of extra-air devices tend to warp the valves of the engines or -which they are used. Superficially, it would appear that a sudden rush of cold “atmospheric” air into the cylinder would set up such an extreme change of temperature In the metal of the valves that it would warp and become distorted. However, a little consideration of what actually happens should dispel this theory. When the extra air is admitted, it, of course, first of all rushes over tlie inlet valve, but its temperature is no colder than that of the mixture of potrol and air drawn into ■'the engine under normal running conditions. The interior of the cylinder is, of course, at a comparatively high temperature, and the air dr.awn in must pass through the cylinder before reaching the exhaust valve. Hence it has, so to speak, the chill taken off it, and so valve warping from this cause becomes a theoretical rather than a practical risk. On vast numbers of ears to-day are fitted extra-air devices, vet we .cannot, recall ever having come across au cuibenticated case of the trouble.