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).
Comparison of engine performance characteristics between a standard and large bore engine configuration.
| Identifier | ExFiles\Box 85\3\ scan0106 | |
| Date | 1st June 1935 | |
| -2- Hs{Lord Ernest Hives - Chair}/Smth.2/KW.1.6.35. We suggest that if the 1.000" pins are found to be satisfactory on the standard engine, we should adopt 1.125" pins on the large bore engine. If this is done and if we use a compression ratio of 6.25/1, the engine will compare with the standard unit as follows :- Compression Ratio 6.25 (Std.6.4) Crankpin length 1.250 (Std.1.000) Power loss due to lower comp.ratio 1% Increase in max. piston loading 12% Max. big end loading - gas pressure Same " " " " - inertia 12 1/2% less Major critical speed 80 r.p.m. lower. Hs{Lord Ernest Hives - Chair}/F.LL.Smith. | ||