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).
Analysis of test results comparing long and short duration cams on a Standard 20/25HP engine.
| Identifier | WestWitteringFiles\T\March1929-December1929\ Scan261 | |
| Date | 16th November 1929 | |
| HS.{Lord Ernest Hives - Chair} } FROM R.{Sir Henry Royce} ~~DY{F R Danby}~~ } Copy to ~~SG.{Arthur F. Sidgreaves - MD}~~ Copy to WOR.{Arthur Wormald - General Works Manager} ORIGINAL STANDARD 20/25HP. x5090. HS{Lord Ernest Hives - Chair}' TEST WITH (a) LONG DURATION CAMS 116°. " " (b) SHORT " " 110°. This experiment I think shews that the carburetter and cross passage are the chief causes of the low power, rather than the valves, (because the superiority of (b) suggests that this camshaft makes the engine the better pump, and shews that at moderate speed gas is pushed back from the cylinder.) Hence from this test the cam duration of 110° is sufficient unless we use the late closing of the inlet valve to reduce detonations, that is, can we increase the compression ratio with (a), and get back part of what we lose at slow speeds. If so, we should certainly then gain substantially at high speeds. I should hope for (a),plus increased compressionratio. Test should include detonations and engine roughness on chassis. [Handwritten on left margin] In hand. R.{Sir Henry Royce} | ||