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).
Engine horsepower test to determine the effect of compression leakage on power output.
| Identifier | ExFiles\Box 19\7\ Scan037 | |
| Date | 19th May 1915 | |
| From Exp. Dept. Copies for: J.{Mr Johnson W.M.} R.{Sir Henry Royce} E.{Mr Elliott - Chief Engineer} Wa.{Mr Wallis} Engine Horse Power Test. Why different cars vary in horse power is always cropping up. Although we are not in a position to say exactly why this happens the results of some tests taken at various times might be of interest. The point I was out to prove in these tests was how much leakage of compression was possible before it had any appreciable effect on the horse power. I made a test on a standard car on the dynamometer by drilling one 1/16" hole through a brass plug on each cylinder. This allowed the compression to escape freely and when the engine was turned by the hand no compression could be felt. | Revs. | Standard. | H.P with 1/16" hole in brass plug. | Difference. | |---|---|---|---| | 750 | 31.1 | 28 | 3.1 | | 1000 | 40.1 | 38.3 | 2.8 | | 1250 | 46.2 | 44.2 | 2.0 | | 1500 | 50.3 | 49.3 | 1.0 | | 1750 | 51.7 | 51.7 | not measurable | The result of this test is what one would expect, that is, the loss in power due to leakage only is in | ||