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).
Comparative table of engine component weights and dimensions for 20HP, 40HP, Lorraine, and Hispano engines.
| Identifier | WestWitteringFiles\R\2October1927-November-1927\ 25 | |
| Date | 19th October 1927 guessed | |
| DETAIL | 20 HP. | Lorraine. | % diff: of Lorraine wt. | 40 HP. | Hispano. | % diff: of Hispano weight. Conn: rod length. | 7.95" | 9.062" | | 11.5" | 11.8" Total conn: rod wt. | 1.551 | 1.763 | + 14% | 3.38 | 3.62 | + 7.3% Big end wt. | 1.187 | 1.250 | + 5.5% | 2.567 | 2.625 | + 2% Small end wt. | .364 | .515 | + 41% | .826 | 1.000 | + 17½% Complete piston, rings, pin etc. | 1.070 | .868 | - 10% | 2.476 | 2.312 | - 6.7% Total reciprocating wt. | 1.434 | 1.38 | + 5.7% | 3.302 | 3.312 | + 3% Small end dia. | .750" | .870" | | 1.00 | 1.275 Big end dia. | 1.50 | 1.771 | | 2.125 | 2.125 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||