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).
Technical notes regarding a Powerplus blower for a Bensport car, covering delivery, specifications, and modifications.
| Identifier | ExFiles\Box 140\1\ scan0015 | |
| Date | 24th August 1932 | |
| ALN x209. To R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} E.6/HP.24.8.32. c. Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} re Blower for Bensport. The following notes refer to two recent visits we have had from Mr.G.E.T. Eyston, of Messrs. Powerplus with regard to the above. We took up with Mr Eyston the question of why we were unable to obtain delivery of a No.11. blower of 2250 cc. for our power test. It was agreed that a No.11. blower should be sent to us at the earliest possible moment but that we should not run it over 4800 r.p.m. This will be enough to give a value for the size of blower proposed. Mr Eyston now reports that the No.11. machine should have been despatched on Saturday last. Mr. Eyston tells us that all owners of supercharged cars expect to run on Ethyl and that in his experience detonation cannot be avoided without it if a useful degree of supercharge is to be employed. The compression ratio he is using on his own car is only 4 to 1. This is with an 850 cc.4 cyl. engine boosted to 8 lbs with an 850 cc. blower. Cylinder head gaskets of copper asbestos will burn out in supercharged engines, a fact which our own experience confirms, and Eyston uses a copper gasket of about .020 thickness and says the thinner the better. Aluminium is said to be no good but soft iron of about .050 thickness is now being tried with success on the M.G's in the T.T. race. With regard to balancing the blower, we find that Messrs. Powerplus are aware of the benefit of making one blade of greater thickness for balancing the floating element of the Oldham coupling, but do not mention that unbalanced couples, as well as forces can be eliminated by suitably | ||