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 test results comparing different carburettor configurations and routes.
| Identifier | ExFiles\Box 1\8\ B001_X100 Engine Chassis-page268 | |
| Date | 15th May 1933 guessed | |
| -2- 2nd. Test. Route :- As before.(i.e. 1st Test) 5.Per.II. with same carb. but weaker needle fitted, taper being .140 - .080". Mileage. 160. Petrol used. 9 galls. 3.5 pts. Petrol cons. 16.95 m.p.g. Time taken. 3 hrs. 35 mins. Average speed. 44.65 m.p.h. There was a pronounced flat spot in the carb. at 30 - 40 m.p.h. which rather spoilt the car's general performance. Top speed practically the same-71m.p.h. 3rd. Test. Route :- Derby, B'ham, Alcester, Evesham, Broadway, Stratford, Warwick, Coventry, Nuneaton, Ashby, Derby. 3.Per.II. 5.Per.II. (Twin S.U. Carbs). (Small P.II type carb.) Mileage 165 165 Petrol used 9 galls 3 pts. 9 galls 4 pts. Petrol cons. 17.6 m.p.g. 17.37 m.p.g. Oil used. Not taken. 1 pt. Oil Cons. " 1280 m.p.g. Time taken. 4 hrs. 30 mins. 4 hrs. 30 mins. Average speed. 36.66 m.p.h. 36.66 m.p.h. This smaller type P.II. carb. has exactly the same flat spot at 30-40 m.p.h. as the larger type carb. has with the weaker needle fitted. There was no flat spot on 3.Per.II. and it still retained its 4 m.p.h. advantage at the top speed. The intake roar on 5.Per.II. was considerably less than when the large type carb. was fitted, being now better than 3.Per.II. 4th Test. Route :- Derby, Loughborough, Six Hills, Melton Mowbray, and return to Derby. This test was run with practically a set throttle position of 33 m.p.h. approximating 2000 engine r.p.m., | ||