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).
Methods for testing and improving engine induction pipe hot-spots.
| Identifier | ExFiles\Box 50\3\ Scan056 | |
| Date | 20th April 1921 | |
| OY. from Hs. {Lord Ernest Hives - Chair} X4305 Hs {Lord Ernest Hives - Chair} 3/LG20.4.21. We have found that the most simple and quick test to show the efficiency of a hot spot is to use an ordinary spirit blow lamp. On the test bench, for instance, we have tried a blow lamp in all different positions along the induction pipe. We protect the induction pipe, where we do not want the heat, by means of asbestos sheets or paste. We can, by this means, get a really good hot spot in any position. We have carried out tests with this arrangement on the road. We have taken a car out and had it misfiring badly and have been able to overcome it by using the blow lamp on the induction pipe. I thought this information might be useful to you in carrying out tests. For instance, if you have complaints on a standard car you could rig up, by means of a blow lamp, a hot spot in a very few minutes and see the effect. Our tests show that the most effective place for the hot-spot on our engine is just above the carburetter but, of course, there are practical reasons why this cannot be done. As we pointed out previously to you, none of our tests confirm that there is any danger of pre-ignition by getting too much heat. We can see no reason why it should be so. We have had an engine running with a coke fire made round the induction pipe and heated by means of a big brazing lamp. The whole thing looked red-hot; we lost considerable power; we increased the tendency for detonation but there were no signs of pre-ignition. You have now had an opportunity of examining R's scheme of hot-spot. What are your criticisms? I am in favour of the corrugated form of hot-spot. We are experimentally rigging up a 40/50 engine with the induction pipe and exhaust system reversed and carrying the induction pipe between the cylinders, arranging the carburetter the other way round and using a butterfly type throttle and are getting a really good hot spot of the corrugated type and blowing straight through it. The chief criticism we have against your arrangement with the 1" pipe through the induction pipe, is that it does not get hot enough - it can, however, with very little modification be made to get much hotter. Are you completely satisfied with that scheme(?) if not, why not? We should like to know from you the date on which you expect 4.EX Car to leave U.S.A. I sincerely hope that you have been able to get on to it some very good-class of American units. When I was at Springfield a Traveller brought round Contd. | ||