Proposing modifications to the 25 HP chassis to make its performance comparable with 1931 American cars.
| Identifier | ExFiles\Box 5a\1\ 01-page092 | |
| Date | 19th February 1931 | |
| C O P Y ------- Btn-1 February 19, 1931. Mr. Hoss-: Re: 25 HP. Chassis. I have given considerable thought to this proposition and enclose herewith copy of a chart, SK-416, which I have prepared. This chart shows, for all 1931 American cars, the relationship of weight and cylinder displacement. It shows that the average successful American car of 1931 carries a weight of about 12 lbs. for each cubic inch of cylinder displacement, and if we assume that all engines are equally efficient in converting this capacity into horsepower, this gives a reasonable basis for computing the power required for a certain weight of automobile. The location of GLR-57 is indicated on this chart, and also of 24-EX. As regards the 25 HP it should be noted that it carries about 17 lbs. per cubic inch. Furthermore, the peak engine speed of some of these cars runs as high as 3800 revolutions, and the horsepower per cubic inch as high as .423. In order to make the 25 HP comparable in performance with these cars, I would suggest: 1. The capacity should be raised to a minimum of 325 cubic inches. 2. The peak of the power curve be raised to 3000 revolutions and output increased to .375 horsepower per cubic inch. From the point of body design, it is necessary also to have an additional three inches of body space. The complete weight of the chassis should be maintained as at present, so that these cars when complete with body should weigh between 3500 and 4000 lbs. this would be reasonably in line with | ||
From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).