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).
Horsepower tests with varying engine compression and carburettor setups.
| Identifier | ExFiles\Box 19\7\ Scan034 | |
| Date | 23th February 1915 | |
| From Exp. Dept. Copies for:- J.{Mr Johnson W.M.} R.{Sir Henry Royce} E.{Mr Elliott - Chief Engineer} Na.{Mr Nadin} Re HP Tests and varying compressions. X.790 Attached herewith is a blue print showing the difference in HP and consumption we obtain by varying the lbs compression on a standard engine by making the clearance volume less. These curves show that the increase in power is not very much if the compression only is increased, it is not much when compared with the increase we obtain by a cut out being open or by fixing a Claudel carburetter. The following tables make this more clear. | Revs. per min. | Standard Silencer on. | Standard cut out open | Compression increased 10 lbs. cut-out open. | Standard comp. space Claudel carb. cut-out open. | |----------------|-----------------------|-----------------------|-------------------------------------------|--------------------------------------------------| | 1000 | 45.1 | 46.2 | 47.4 | 48.75 | | 1500 | 60.0 | 65.4 | 67.8 | 69.5 | | 2000 | 66.2 | 72.6 | 77.7 | 80 | The curves show that as the compression is increased the HP does not fall off as quickly at high speeds. In making these tests I found that it was essential to clean the carbon out of the cylinders every time we altered the compression, this was necessary to obtain a true comparative test, carbon deposit in an engine makes more difference than | ||