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).
Brief report on work carried out with the Graham Supercharger on a B-12 unit for a Bentley.
| Identifier | ExFiles\Box 140\1\ scan0107 | |
| Date | 31th December 1934 | |
| 4209 To E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Mths.{Reg Matthews} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Mths.{Reg Matthews}1/KW.31.12.34. Graham Supercharger on the Bentley. This report is only a brief resume of the work carried out so far with the Graham Supercharger on B-12 unit. When first fitted the Intermediate Pipe was as shown on B.V.68, and no water jacket was fitted to this pipe, the normal water jacket on the volute of the Supercharger was used as on the Graham car. The power output with this arrangement and with the packing washer between the two halves of the rotor casing and with the Graham carburetter was 126 B.H.P. at 4000 r.p.m. and the boost pressure and temperature were respectively 4.0 inches of mercury and 40°C. The boost pressure and temperature at 4,500 r.p.m. were 5.45 inches and 52°C. In order to see what effect the heat on the volute had we ran a test at 4,250 r.p.m. with cold water to the volute casing and the power output was increased from 126 to 134.5 B.H.P. and the corresponding boost pressure and temperature were 5.025 inches and 29°C., the temperature showed a reduction of 17°C. over the previous figure at this speed when using the hot jacket. In order to further increase the boost we removed the washer from the rotor casing, the power curve with this arrangement and with the Graham carburetter is shown on B.V.69, the maximum power output was 129 B.H.P. at 4,250 r.p.m. when using hot water to the rotor casing, an increase of 3 B.H.P. With no heat to the volute it was impossible to run at full throttle below 1,500 r.p.m. due to the building up of fuel. With this original long intermediate pipe slow running was not very good. The engine would idle at 320 - 340 r.p.m., but was rather "lumpy"; the slow running tests were carried out with .020 tappet clearance. B.V. 69 | ||