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 modifications involving compression, Zephyr pistons, and their effect on power and fuel consumption.
| Identifier | ExFiles\Box 19\7\ Scan035 | |
| Date | 23th February 1915 guessed | |
| Wor{Arthur Wormald - General Works Manager}/EH4/L23215. 2. raising the compression 3 lbs. The range of compressions we used was limited by the skirt on the Zephyr pistons, the skirt would have come out in the counter-bore when using the low compressions if we had machined any more off the bottom. We used the new Zephyr pistons, they have stood up without giving any trouble, it might be on these pistons that they have altered the type of steel as well as strength- ening them up. The improvement in the consumption is marked, the mixture was adjusted to give the maximum power, if it had been adjusted for maximum consumption we should have used about 10% or 12% less petrol. Mr Platford finds that now all cars fitted with the same size carburetter and with cut outs that he obtains hardly any appreciable increase in power by having 24 1/2 sq. inches capacity instead of 25 1/2 sq. in. | ||