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).
Camshaft design, compression ratios, and fuel choices to achieve high power from an engine.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan245 | |
| Date | 5th June 1931 | |
| ORIGINAL HS.{Lord Ernest Hives - Chair} ) FROM R.{Sir Henry Royce} BY.{R.W. Bailey - Chief Engineer} ) C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} RHC.{R. H. Coverley - Production Engineer} re. HIGH POWER FROM P. 2. E.{Mr Elliott - Chief Engineer} will send the technical data upon which the design of the camshaft referred to in my memo. of this morning (R1/M5.6.31.) is based, and we think that this is the limitation of practical usefulness. With these camshafts the power may be slightly lower than with the aero engine cams, the reason being that we did not consider noise and roar with the aero engine work. If we find the HP. less than we expect we must try and regain it by short induction passages, and low depression at the carburetters, all the air velocity to be available for ramming so as to get best volumetric efficiency. We do not mind if we lose a little torque at low speeds. This is what we have been expecting and so far been pleasantly disappointed. A small loss of power at low speed will mean that the compression pressure is less, and the risk of detonations less, and therefore we should work definitely to get this one of the characteristics. We now have to move to the highest compression ratio that we can possibly use. This we hope will be in the neighbourhood of 6 to 1 with a clean engine, and should this not be possible without doped fuel then we must run with our special non-detonating fuel - i.e. petrol, tetra ethyl lead, and benzol. We understand alcohol in the mixture has serious limitations. In conclusion we think it would be very unwise to attempt either masked valves, extraordinary high lift, flat valve seats, or even 30o, or impractically heavy accelerations. We agree however to your trying the 30° valve seats, but we must bear in mind that it is possible it will reduce the turbulence and force us to a lower comp. ratio. My personal faith is in the highest comp. ratio that you can possibly run with, even if it demands salt cooled valves and special fuel. R.{Sir Henry Royce} [STAMP: RECEIVED 8 JUN 1931] [Handwritten: Filed 87090. 87771.] | ||