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).
Report page discussing engine detonation, turbulence, and ignition tests comparing an original aluminium head with an alternative head on a Phantom engine.
| Identifier | ExFiles\Box 42\4\ Scan051 | |
| Date | 10th December 1926 guessed | |
| contd :- -2- greater turbulence but with this first head no difference could be detected. Consequently we have continued with the smaller clearance (.058) for these tests. The performance of the original alum. head has been reported but we reporduce some of the curves here for the purpose of comparison. It will be remembered on summing up the results, we came to the conclusion that with regard to detonation, at a part- icular compression ratio, the characteristics of this engine and the standard Phantom seemed very similar as far as we could estimate from work on the test bench. It was further shewn that synchronised ignition resulted in reducing the spark advance required to obtain maximum torque, particularly so at the low speeds, and should therefore make less demand upon the ignition oil relay. In practice we think this may lessen the detonations although at the moment we have no direct evidence but information on this point will be gathered from road tests. TESTS WITH THE ALTERNATIVE HEAD HAVING THE SMALLER OPENING BETWEEN THE COMBUS- TION SPACE AND THE CYLINDER. We have no direct means of measuring the relative turbulence of the different engines but can study and compare the factors which we consider are affected by turbulence. It is some of these factors such as the tendency to detonate, the ignition advance required and self-ignition after switching off, in which we are particularly interested as being some of the troublesome points on our standard engine. Raising the compression ratio is probably one of contd :- | ||