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).
Petrol consumption, cylinder bore wear, and four-cylinder engine tests.
| Identifier | ExFiles\Box 174\3\ img317 | |
| Date | 3rd October 1941 | |
| Petrol Consumption. We have effected an improvement in petrol consumption on B.V and B.60 cars of 1½ - 2 m.p.g. by carburetter modifications. Recent check runs by Rm.{William Robotham - Chief Engineer} on 12.B.V and J.B.30 have given 18-3 as against 16.7 m.p.g. and 19.3 as against 16-3 m.p.g. respectively, with the old and new carburetter settings. All our cars, including customers' cars, will have their jets and needles changed as soon as circumstances permit. When we run on these weak mixtures, however, we find that the behaviour of cars fitted with the same pieces vary. There is scope for considerable post war development here. Cylinder Bore Wear. Tests are still being run on our cars with chromium plated bores, but there has been insufficient mileage run since the last report to make any further comment. AG's trials car, Breeden's car and Devereux' cars have had their bores chromium plated. Records will be taken when sufficient mileage has been run. FOUR-CYLINDER ENGINE. Tests in 1-R7-1. We have practically completed the engine mounting. We consider the engine to be reasonably quiet and one or two light periods remaining are a subject for post war development. We are now engaged in fitting up the S.U. carburetter. Since the main justification for fitting such a small engine is economy, we have been working on fuel consumption. With the Stromberg carburetter we can get 23 m.p.g. when the car is driven hard, which would be 26 m.p.g. normal driving. To get this consumption with a water heated hot spot, however, we shall have to have radiator shutters or their equivalent and also a very efficient starting carburetter for getting away from cold. The preliminary tests have at least shown us what we have to start work on after the war. The performance is quite fair. The complete car weighs 31 cwt. or 3½ cwt. more than the Hillman 14. Its mean top speed is 69 m.p.h., its acceleration 10 - 30 31.3 seconds against the Hillman 28.6. Past experience suggests that its performance will be improved slightly with an S.U. carburetter. | ||