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).
Road and test bed results for a supercharged Bentley, including diffuser development.
| Identifier | ExFiles\Box 140\1\ scan0190 | |
| Date | 30th October 1935 | |
| To Sg.{Arthur F. Sidgreaves - MD} & Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} c. to Ey. x-209 Ha/Smth.20/KW.30.10.35. Supercharged Bentley. Work carried out since issue of Ha/Smth.12/KW.12.4.35. Results on the Road. 3-B-IV. We have run a supercharged unit in chassis over the rocker cover, and the power curve of the unit was as shown in Hs.{Lord Ernest Hives - Chair}1909 attached to our previous report. There was a marked improvement in the performance of the car, and the hesitation in pick-up which was noticeable on the test bed was absent on the road. The gear whine from the supercharger drive was practically inaudible inside the car, but we do not think that any type of worm drive is sufficiently durable for this work. When the engine was in the chassis the slow running was poor, and our subsequent test bed work has been directed to improving slow running and testing a diffuser type supercharger. We are about to try a 3.500" bore supercharged unit on the road, embodying features which we have found to improve slow running. Diffuser. Ex.17516. Hs.{Lord Ernest Hives - Chair}2212 shows comparative characteristic curves for this supercharger and for the previous non-diffuser supercharger, taken at the same rotor top speed. For small deliveries the diffuser gives an extra 10% efficiency, but the difference is less marked at higher outputs. | ||