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).
The effects of a heated pipe, fan cooling, and fuel detonation on engine performance.
| Identifier | ExFiles\Box 75\2\ scan0253 | |
| Date | 19th March 1921 | |
| contd. -2- may be that the effect of these has been to reduce rather than increase the flow of gas in the 1" pipe. Taking them out would prove this point and would reproduce the pipe as at present fitted on Springfield cars. We have found that the cooling effect of the fan draft on the front end of the manifold is very marked even in hot weather, causing a difference of 20° or 30°F.{Mr Friese} temperature between thermometers mounted at either end of the pipe. This was proved by stopping the fan, upon which the temperature became equal. It may be that Mr. Hives is trying the temper-ature of the 1" pipe, disconnected from the manifold, had the fan blowing over it, which we believe would cause a certain drop in temperature, and might also cool the oil reservoir which Mr. Hives fixed on the centre of the pipe. We are anxiously waiting for a final design of a heated pipewhich will produce a really consistent improvement, and shall adopt it as soon as it is possible to get it on the cars. We shall first, however, need to assure ourselves by trial with American gasoline that it will not produce the serious troubles which we encountered with the early pipe heated at the Tee, and which we put down to pre-ignition due to lack of the cooling effect of the inlet gas on the battery plugs. During Mr. Platford's visit we have been able to observe the difference in tendency to detonate between different gasolines. This difference is apparently not shown by dis-tillation tests, Gulf, which is a bad detonator, showing no worse on the distillation curve than Socony, which is fairly good. From what we can learn, the detonating tendency appears to depend on the particular series of hydrocarbons to which the heavy ends belong, since if they have a low self-ignition temperature the gas detonates worse than one in which the self-ignition temperature of the heavy ends is high. SUMMARIZING. 1. The 1" heated pipe has produced good results in a number of cases. Mr. Hives appears to think that probably we were lucky with this device only in the one case. 2. We know that at least in one case the pin in the throttle was fitted on a customers' car and did not give the customer complete satisfaction, but that after the heaetd pipe was added, the running of the engine was improved sufficiently to satisfy him. 3. We think the only complete trial of the heated pipe would be under American winter conditions and with American fuel. 4. We think the heated throttle should be tried out in the same way. contd:- | ||