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).
Power and induction system experiments for a Supercharged Bentley Unit.
| Identifier | ExFiles\Box 140\1\ scan0127 | |
| Date | 4th February 1935 | |
| To E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Smth.8/KW.4.2.35. Supercharged Bentley Unit. Power. Since our previous report on this subject (Hs{Lord Ernest Hives - Chair}/Mths.{Reg Matthews}1/KW.21.12.34) we have been experimenting with valve timing, with a view to picking up some low speed torque. The results are given in the attached curves. The various timings used are as under :- | | IO | IC | EO | EC | |---|---|---|---|---| | Standard Bentley | 4°E | 49°L | 49°E | 5°L | | Standard 20/25 | 3°L | 40°L | 44°E | 6°L | | Early 20/25 | 6°E | 31°L | 53°E | 3°E | Induction System. The induction arrangement was as shown in the sketch. Hot water was circulated through the intermediate induction pipe jacket, but no other heating was used. With this system the engine would slow run at a speed of 250-300 r.p.m. with the S.U. carb. and of 200-250 r.p.m. with the Stromberg carb. There was very little difference in the slow running between the various valve timings. It appears that the supercharger, by mixing up the charge, is a definite help to slow running. The intermediate pipe rises slightly from the blower in order to clear the rocker cover, and there is a slight tendency for petrol to build up in the lowest point at very low speeds. This, however, is not serious, and we believe that the trouble can readily be overcome by the provision of a small exhaust hot-spot and a drain at the lowest point. | ||