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).
Modifications to a supercharged Bentley's induction system to improve slow running and distribution.
| Identifier | ExFiles\Box 140\1\ scan0157 | |
| Date | 12th April 1935 | |
| To Mr. A Wor.{Arthur Wormald - General Works Manager} c. to R.{Sir Henry Royce} c. to BY.{R.W. Bailey - Chief Engineer} c. to Du. c. to Bn.{W.O. Bentley / Mr Barrington} Supercharged Bentley. Work carried out since issue of Hs{Lord Ernest Hives - Chair}/Smth.8/ML.4.2.35. Blow Running, Distribution, etc. Since issuing the above report we have tried one or two modifications to the induction system in order to gain some information on slow running, distribution and loading up. The first intermediate pipe, which ran over the rocker cover between the supercharger and the manifold, had a low point near the supercharger. We replaced this pipe by one which sloped towards the manifold all the way. Without having any detrimental effect on slow running this pipe showed less liability to load up with petrol at low speeds. The pipe was water-jacketed on the straight portion as previously. The straight portion made an angle of about 85° with the manifold. We found that violent heating of the Tee joint in the manifold did not improve slow running. We next mounted the blower on the offside of the engine, driving it through the water pump. It was located beneath the manifold, into which it fed through a short, round bend, water-heated (see photograph and sketch). The blower could not be arranged to deliver at right angles to the manifold, the actual angle being about 55°. With this arrangement the high and middle speed distribution was good at F.T. At lower speeds F.T. there was a tendency, although not an excessive one, for the two front cylinders to run richest and the two middle ones to run weakest. This indicates that the petrol tended to cling to the inside corners of the Tee connection in the manifold. Slow running was not very good - certainly not as good as with the blower feeding over the rocker cover. The system was very bad for loading up. | ||