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).
Design points and modifications for the Bensport Engine.
| Identifier | ExFiles\Box 3\4\ 04-page071 | |
| Date | 7th July 1932 | |
| HS.{Lord Ernest Hives - Chair} } FROM R.{Sir Henry Royce} E.{Mr Elliott - Chief Engineer} } X4853 R5/M7.7.32. C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} BY.{R.W. Bailey - Chief Engineer} DA.{Bernard Day - Chassis Design} BENSPORT ENGINE. This has worried me greatly during the past fortnight, as regards where the supercharger ought to be, the convenience for the driver, and for his feet, and the pedals, also the damage to the supercharger by backfires etc. The situation now seems to be clearing itself up with the following points: (1) The crankshaft is to be made stiff enough, and the inertia kept down so that we can run at 5000 RPM. without risk of breaking the crankshaft. (2) That 4" seems to be the best stroke, this giving 2880 cc, which we understand is just under the limit for the 3 litre class. We have to make the very best of this shaft, big ends, and pistons. (3) It then occurred to me that our pistons might be somewhat lighter because they ought not to need to be split. The small bore and the need of silence would seem to suggest that this was unnecessary. With an unsplit piston it might be made lighter, and therefore help the master period of the crankshaft. (4) As regards the drive at the back end it is now found that our single carrier wheel scheme can be got in without a detachable wheelcase cover. At the most it will only be necessary to modify the flywheel, and it will be seen that we can alter the internal and external diameters of the main section of the flywheel providing we use P. 2. or Bosch type starter motor. We hope Mr. Eyre will be able to send you a print of our version of the rear end which can be compared with your version, and the best of each adopted. (5) We are very pleased that the engine has been pushed forward owing to the absence of the supercharger at the front, because the flywheel case embarrassed the pedals, and it required a most complicated dashboard. All this has now disappeared. (1) | ||