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).
Comparing the performance specifications of the Phantom and Bentley against other contemporary cars.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan87 | |
| Date | 12th June 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. -2- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/RM{William Robotham - Chief Engineer}4/LG251025 140 clutch B.HP. available while the Phantom has only 109 B.HP. The increased efficiency at high speeds on the Bentley may be accounted for by four overhead valves per cylinder and higher compression ratio. It is, however, a remarkable power output being 20% better than the Hispano, an engine of the same size. | CAR. | Wt. of car. No passengers. Tons. | Displace-ment. | Direct Drive ratio. | Displ:per ton per wheel rev.of 104" | | :--- | :--- | :--- | :--- | :--- | | 40 HP. Fiat. ++ | 2.15 | 4,766 | 4.08 - 1 | 9044 | | Austro-Daimler | 1.25 | 2,650 | 4.9 - 1 | 11,200 | | 20 HP. R-R (pre. F.W.B.) | 1.50 | 3,130 | 4.6 - 1 | 10,050 | | Hispano-Suiza. | 2.25 | 6,600 | 3.365 - 1 | 9,900 | | Phantom. | 2.568 | 7,660 | 3.467 - 1 | 10,400 | | Bentley. | 2.00 | 6,600 | 4.16 - 1 | 13,700 | ++ Open car. All others are closed cars. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||