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).
Power development for the 20 HP engine, focusing on camshaft experiments.
| Identifier | ExFiles\Box 5a\5\ 05-page049 | |
| Date | 23th May 1927 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/ACL. c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} SY. c. to OY. X5771 Hs{Lord Ernest Hives - Chair}/ACL1/LG23.5.27. 20 HP. RR. POWER DEVELOPMENT : CAMSHAFT EXPERIMENTS. X5090 In a previous report was shewn how the power output of the 20 HP. had been increased by the following factors :- (1) Carburetters giving low induction pipe depression. (2) Larger valves. (3) High compression ratio. It was also explained that in order to obtain the maximum advantage from larger valves it was necessary to employ carburetters giving a low induction pipe depression. We have followed up these experiments by testing a camshaft which gave longer duration of opening to both inlet and exhaust valves in the endeavour to maintain a greater volumetric efficiency at the higher speeds. The experiments have proved to be very promising resulting in an increase in maximum power of 21% due to the camshaft alone. The peak of the power curve is now raised above 3000 r.p.m. and only a small decrease in power is manifest at the lower speeds, which is what we should expect with a long duration inlet cam. It is possible however that this may prove a definite advantage in allowing the use of a slightly higher compression ratio without increase the tendency to detonate at low speeds. The curves given on sheet 1. shew the increase in power effect by the use of long duration cams above the contd;- | ||