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).
Results of tests conducted on hot-spot induction pipes to improve engine torque and consumption.
| Identifier | ExFiles\Box 50\3\ Scan094 | |
| Date | 2nd June 1921 | |
| X4305 To R. {Sir Henry Royce} from Hs. {Lord Ernest Hives - Chair} c. to CJ. c. to BN. {W.O. Bentley / Mr Barrington} c. to E. {Mr Elliott - Chief Engineer} c. to Da. {Bernard Day - Chassis Design} c. to BY. {R.W. Bailey - Chief Engineer} c. to EWT. for R.R. Inc. attention of OY. Hs {Lord Ernest Hives - Chair} 8/LG2.6.21. X.4305 - HOT-SPOT INDUCTION PIPES. We have completed the tests with the hot-spot fitted close to the throttle. We found that the most easy way to apply this was to use one of the old-induction pipes in which there was a right-angle bend above the throttle. On that pipe there is room to get an exhaust jacket round the bend. We used an exhaust pipe 1.25" diameter leading to the hot spot and another pipe 1.125" diameter leading from it and returning to the front silencer. We first ran this engine with the exhaust disconnected from the hot spot. We were running with Mex petrol 20% paraffin added. With this fuel and the water in the engine at 40°C, the engine would not give a steady torque at 500 revs., full power - it was either popping due to weakness or missing fire due to richness. We increased the water temperature in the engine to 80°C still having no exhaust to the hot spot, we then got an even torque at 500 revs. full power over a range of 18 pts. up to 24 pts. per hr. on the consumption. We then connected up the hot spot - with this connected we could run the engine with the water at 40°C and maintain an even torque from 13 1/2 to 32 pts. per hr. This is the best range we have been able to get on any pipe. Undoubtedly, the right position for the hot spot is at the throttle or immediately above it. Contd:- | ||