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).
Modifications to increase the power output of the 20 HP engine.
| Identifier | WestWitteringFiles\Q\2-July1927-September1927\ 124 | |
| Date | 21th September 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} BY.{R.W. Bailey - Chief Engineer}✓ c. to OY. ORIGINAL. Hs{Lord Ernest Hives - Chair}/ACLE/LG21.9.27. INCREASED POWER OUTPUT OF 20 HP. Y5771 Y5230 We have previously reported the increased performance obtainable from the 20 HP. RR. engine by employing larger valves, low induction manifold depression, long duration cams etc. and given an analysis of the gain due to each individual alteration. We have now fitted up an engine embodying all these features together with the 1.G.1. type of crankshaft damper to avoid the 'master' period which we think is suitable for testing in a car. It is proposed to fit this engine in a car at the earliest opportunity in order to obtain some information as to its road performance. The following is a list of the modifications :- (1) Larger valves 1.400 dia. (2) Long duration camshaft - timing diagram appended. (3) Vertical Stromberg carburetter type OX3 with straight 'T' type induction manifold (see sketch). (4) Modified exhaust manifold leading into a 2" dia. down pipe. (5) Compression ratio 5.45 to 1. (6) Stiffer valve springs - rating 86 lbs/sq.in. (7) 1.G.1 type of crankshaft damper. Although higher power has been obtained when using two carburetters working at a very low depression, we thought it preferable for this purpose to employ only one low depression carburetter. contd :- | ||