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 a Lorraine Dietrich engine to identify potential improvements for the 20 HP engine's power development.
| Identifier | ExFiles\Box 19\7\ Scan098 | |
| Date | 1st April 1927 | |
| x790 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} Hs{Lord Ernest Hives - Chair}/ACLl/LG1.4.27. X5771 X3555 20 HP. RR. POWER DEVELOPMENT EXPERIMENTS. When ak analysing the results of tests made on the Lorraine Dietrich engine there appeared considerable evidence to shew that the high power output, when considered relative to our 20 HP. engine, was in a large measure due to three outstanding causes, viz :- (1) The high compression ratio. (2) The low induction pipe depression. (3) The lower gas velocity past the valves. apart from other factors such as valve lift duration etc. which were briefly discussed in a report on that engine. Hence there seemed justification in testing if an improvement could be effected in the 20 HP. RR. by reproducing similar conditions. The latter two of the above factors - i.e. low induction pipe depression and lower gas velocity - seemed the most promising lines for development as we have already experienced the improvement introduced by higher compression ratios but have been somewhat limited in this direction by the increased tendency to detonate at low speeds. We had at our disposal a 20 HP. cylinder head fitted with larger diameter valves - 1.400 dia. instead of the standard 1.200 dia. This results in an increase of area past the fully lifted valve of 40%. The head was made a considerable time ago and had been previously tested but at the time it was considered that the small power increase obtained did not justify an alter- Contd | ||