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 three tests on various induction pipe configurations.
| Identifier | ExFiles\Box 124\3\ scan0258 | |
| Date | 4th December 1934 | |
| -2- Induction Pipes. Test No. 1. 1.375 bore pipe, balanced (no centre restriction) with 2 SpectreCodename for Phantom III Carburetters placed in the corresponding positions of the SpectreCodename for Phantom III arrangement between cylinders 1 & 2 and 4 & 5, using the same degree of water hot spot as on the standard Bentley pipe. Result. Slow running very poor, actually worse than that of the standard Bentley. By fitting the standard Bentley restriction in the centre of the pipe (EB.318) and thus preventing the gas from surging from one end of the pipe to the other, slow running was improved, being now about as good as Bentley. Varying sizes of holes in plain plates were tried in the centre of the pipe, but the bush type of restriction (EB.318) was found to be the best. Test No. 2. Single carb. (20/25 horizontal) fitted to the centre of the pipe (no restriction). Result. Same as the first result in test No. 1, gas surging in the pipe etc. No noticeable improvement by applying extra heat. Test No. 3. Induction pipe and carbs. as Test No. 1, but with the complete length of main pipe water heated and centre restriction EB.318. Result. Slight improvement, but uneven and unreliable below 350 r.p.m. NOTE - Maximum power loss = 5 B.H.P. at top speeds. | ||