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).
Performance and fuel consumption comparison of carburettor and exhaust systems on a 124ccs capacity engine.
| Identifier | ExFiles\Box 123\1\ scan0011 | |
| Date | 27th December 1939 | |
| -2- time taken to accelerate from 0 MPH. to any given speed. Our figures are the average of 6 clocking times taken 3 in each direction over the same stretch of The twin S.U. carbs. also showed a better petrol consumption equal to 1.0 m.p.g. on the Derby, Ashbourne Buxton Matlock route at an average speed of 45 m.p.h. The Zenith Constant petrol consumption tests gave similar results as shewn on graph. The method employed here is to record by stop watch the time taken for the engine to use 1/10 of a gallon of petrol from an accurately marked glass container, whilst the car is being driven in top gear at a constant speed. We also ran 2.B.50. car with the B.III engine, and fitted with Twin S.U. carbs. over the same route and at the same average speed, and obtained a similar petrol consumption i.e. 15.7 m.p.g. We also ran 3.B.50. car with a twin exhaust system and whilst its performance was much better 5 secs. from 10-70 m.p.h. we could not register any difference whatever in petrol consumption or on detonation. The system was run in conjunction with twin S.U. carbs. We know from previous tests on Brooklands that the Twin exhaust system also gives us 5 m.p.h. higher maximum speed. Text from graphs: Top Graph: 3B50 - B60 N° 4 EB 3844 CYL HEAD 6.35:1 124 CCS CAPACITY BHP ERPM A - TWIN SU CARBS B - DUPLEX STROMBERG Bottom Graph: MPG MPH A TWIN SU'S B DUPLEX STROMBERG 45 MPH AVGE BUXTON ROUTE A - 15.6 M.P.G B - 14.6 M.P.G | ||