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).
Long duration camshaft experiments conducted on the Phantom engine.
| Identifier | WestWitteringFiles\Q\2-July1927-September1927\ 38 | |
| Date | 16th August 1927 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/ACL. c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to DA.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer} c. to BY.{R.W. Bailey - Chief Engineer} RG.{Mr Rowledge} ORIGINAL. Hs{Lord Ernest Hives - Chair}/ACL1/LG16.8.27. Hs.{Lord Ernest Hives - Chair} absent. X.8090 LONG DURATION CAMSHAFT EXPERIMENTS ON PHANTOM. Experiments with long duration camshafts have previously been made on the 20 HP. RR. and promising results were obtained. Similar tests have now been carried out on the standard Phantom engine. For the purpose of this experiment a camshaft was prepared in which the duration of lift of the inlet valve was increased by 28° (on the flywheel) by inserting 14° dwell in the cam at full lift. Similarly the exhaust duration was increased by 12°. The relative positions of the cams were so arranged that the point of opening of the inlet and closing of the exhaust valves remained the same as the standard camshaft. This camshaft resulted in the power being maintained better at the high speeds where a 14.8% power increase was obtained at a speed of 2750 r.p.m. The peak of the power curve was not moved to an appreciably higher speed as was evident in the case of the 20 HP. when fitted with the two Zenith carburetters. To take full advantage of the longer duration cams it appears necessary to work with fairly low induction pipe depressions. The power output at the lower speeds is slightly less with the long duration cams and there appears less tendency to detonate due no doubt to the lower effective compression ratio. contd :- | ||