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 tests comparing S.U. carburettors with R.R. Semi-expanding carburettors.
| Identifier | ExFiles\Box 1\8\ B001_X100 Engine Chassis-page264 | |
| Date | 15th May 1933 | |
| X4027a Rm.{William Robotham - Chief Engineer} from G.H.Whyman. 15.5.33. PETROL CONSUMPTIONS WITH S.U. CARBS. & R.R. SEMI-EXPANDING CARBS. We have now completed a series of petrol consumption tests on 3.Per.II and 5.Per.II cars, with Twin S.U. Carbs., R.R. Semi-expanding Cards, small P.II. type, and large P.II. type. The following tables give the results obtained :- 1st Test. Route :- Derby, Loughborough, Six Hills, Melton Mowbray, Oakham, Stamford, Huntingdon, and return back to Derby. 3.Per.II. (Twin S.U. Carbs.fitted). Mileage 160 Petrol used 8 galls. 7 pts. Petrol Cons. 18 m.p.g. Oil Used 1.5 pts. Oil Cons. 853 m.p.g. Time taken 3 hrs. 50 mins. Average speed 41.74 m.p.h. 5.Per.II. (Large P.II. type carb. fitted with needle taper .140" - .070"). 160 10 galls. 2 pts. 15.6 m.p.g. 1.0 pt. 1280 m.p.g. 3 hrs 50 mins. 41.74 m.p.h. There was very little difference in the performances of the two cars except at the top speeds when 3.Per.II. definitely prooved itself a little faster. Maximum speeds attained on road over the same stretch, and in the same direction were :- 3.Per.II, 75 m.p.h; 5.Per.II, 71 m.p.h. Both cars suffer from intake roar, 5.Per.II. being much worse than 3.Per.II. Cont'd - | ||