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 fuel consumption and engine performance between experimental cars 1 EX and 6 EX with different back axle gear ratios.
| Identifier | Morton\M22\ img182 | |
| Date | 23th August 1920 | |
| [Header] To HS.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} Copy to C.J. [Copy to] WOH. [Copy to] DA.{Bernard Day - Chassis Design} [Copy to] BY.{R.W. Bailey - Chief Engineer} [Copy to] EFC. [Handwritten Notes & Stamps at top right:] X31 conditions 1EX R S H R6/G20/8/20 [Stamp:] ORIGINAL [Stamp:] RECEIVED 23 AUG 1920 [Handwritten References:] X.3545 X.3763a X.3923 [Subject Line] RE LOWER RATIO OF BACK AXLE. COMPARISON OF 1 EX. WITH 6 EX. [Body] In my recent comparison of 1 EX. with 6 EX. I found no apparent disadvantage with the lower geared car except that it seemed more difficult to obtain good consumption. I did, however, on a run of 50 miles, get 16.6 miles per gallon. As far as I could tell this consumption was two miles to the gallon less than I could get on 1 EX. with the standard gearing. The feeling of the engine, however, was definitely, though slightly, more powerful, and definitely though slightly, smoother, owing one supposes, to the fact that at slow speeds the engine was generally turning more quickly. The maximum speed of the two cars was not tested, as the speed indicator belt of 6 EX. appeared to be slipping. At high speeds the engine of both cars was quite satisfactory. There was no definite vibration or rattles with either. [Signature] R.{Sir Henry Royce} | ||