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).
Performance comparison of compression ratios between Ford, Cadillac, and a discussion on potential performance increases.
| Identifier | ExFiles\Box 160\2\ scan0089 | |
| Date | 18th July 1925 | |
| Oy1-E-71825 -3- July 18th, 1925. (7) Referring to the compression ratios, it will be seen that Ford is 3.9, Cadillac 4.8, and Rolls-Royce 3.92. Other things being equal the Cadillac touring car should therefore show a slightly better performance on hills than the Rolls-Royce, but should be rougher and have more tendency to detonate. (8) On the eighth column the compression ratios have been allowed for, taking 4 to 1 as standard and multiplying the figures of column 7 by a factor representing the amount by which the power for a given displacement should differ in the various engines because of the various compression ratios. This may be taken as a table of comparative "expected performance on high gear". The Rolls-Royce has the lowest figure on this corrected list. Results differing from this will be due to better or worse detail design in the engine and chassis. A note (2) is added covering the possibilities of increased performance in the present car. Namely, reduced axle ratio, 13/51 bore increased 1/8" (this increased capacity and compression ratio). Weight of cars reduced 150 lbs. The "performance figure" 45.2, shows that such changes should make a big increase in the performance of the car. A note (3) is also added on the "New PhantomCodename for PHANTOM I". The figure on touring car weight is somewhat doubtful. It takes into account the increase due to servo, front brakes, and engine. Oy. MO/E | ||