IS THE DIESEL THE ENGINE OF THE FUTURE? Two expert’s views on the subject. been investigating the special problems Diesel

WITHIN the next few years, Diesel cars will reduce the cost of motoring to half or one-third its present figure,” is the opinion of G. E. T. Eyston, who recently set up a world’s record in a Diesel racer at Brooklands.

“Thanks to its economy, the Diesel engine is now widely used in commercial vehicles, and I see no reason why the same economy should not be possible on private cars.” How to save engine weight is the problem facing Diesel engineers. Weight reduction demands still more efficient lubrication at temperatures far higher than those of a petrol engine under stresses that are much more severe. According to Mr. E. A. Evans, Chief Chemist of the Wakefield Company, who have for years

of Diesel lubrication, the need for highgrade lubricating oil is even more important than on a petrol driven engine.

During early trials of the first Dieselengined motor vehicles on ” economical” oil, so much sludge was formed that the oil” could be dug out of the crankcase after a few thousand miles.” “Another serious problem is dilution,” he said. ” In a Liesel engine the lubricating oil is specially liable to become diluted, and in time unfit for use, as there is a tendency to incomplete combustion. With a petrol engine, except when starting up from cold, nothing is to be gained by using an over-rich mixture. With a Diesel engine, on the other hand, the richer the mixture the greater the power up to a

point, and the greater the danger of oil dilution.

” A petrol engine runs at full compression only when the throttle is wide open. By its nature, however, a Diesel engine must run at full compression even when it is ticking over. It has in consequence normally to withstand a stress which in its intensity can be compared only with the stress imposed upon the engine of a racing car.

And yet it is impossible to use a heavy grade lubricating oil to stand up to these stresses, for heavy oil plus the very much higher compression would make the engine all but immovable on a cold morning. This imposes demands upon the lubrication that are in fact almost diametrically opposed to each other.”