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).
Carburetter tests for the 20/25 HP model, comparing an experimental S.U. carburetter with the standard version.
| Identifier | ExFiles\Box 5a\5\ 05-page198 | |
| Date | 13th November 1933 | |
| To Mr. Hives From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} 45771 H.{Arthur M. Hanbury - Head Complaints} Mr. R.{Sir Henry Royce} Mr. C. Mr. G.{Mr Griffiths - Chief Accountant / Mr Gnapp} Mr. CARBURETTER TESTS - 20/25 HP. On 13.11.33, we demonstrated our expl. car 18.G.IV. fitted with an S.U. carburetter having a throttle edge slow runner. This car was compared with the standard 25 HP. demonstration car GYL.31. The weights of the two cars were almost identical. The advantages claimed from the modified carb. are:- (1) Better slow running. (2) No popping in the exhaust. (3) Elimination of the sticking air valve, which has been a perpetual source of trouble on the 25 HP. (4) Improved performance. The test was satisfactory in demonstrating these points in so far as they could be demonstrated on any single day. There was some discussion as to the fact that the expl. car, which had run for something like 60,000 miles since overhaul, was more noisy than GYL.31, but to show that the improved performance was not obtained at the expense of increased engine noise and roughness, the expl. carburetter was put on the trials car, which was then driven back to London. Hearing nothing to the contrary we presume series were satisfied that the carburetter did not make the car any less a Rolls-Royce. Trying the cars side by side for performance, it was evident that the acceleration from 20 M.P.H. had been improved by the experimental carburetter, the top speed also being increased by about 3 M.P.H. Petrol starvation occurred at high speeds on the expl. car which was thought to be due to the autovac. Investigation however proved that it was due to the petrol tap having become partially obstructed by fluff. A query was raised with regard to petrol consumption. On a fast give and take road we find that we are able to average about 6 M.P.H. more with the new carb. than with the standard one. Under these conditions the petrol consumption is increased by about 1 M.P.G. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||