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).
Tests for distribution and power outputs using the Spectre Induction System on a Bentley engine.
| Identifier | ExFiles\Box 93\2\ scan0010 | |
| Date | 15th May 1934 | |
| SpectreCodename for Phantom III. Distribution and Power Outputs. Tests have been carried out to determine whether any effect is noticed when running two S.U. carburettors in the staggered positions of the SpectreCodename for Phantom III Induction System. These tests were carried out on a Bentley engine, fitted with a standard 20/25 HP. camshaft. The size of the Induction pipe used was 1.375" bore, with two 1.250" (throttle) S.U. carburettors. Test No. 1. Carbs. fitted up in the standard Bentley position, between cylinders 2 and 3, 4 and 5, show a distinct improvement in distribution over the standard Bentley system, with a slight increase in power at top speeds. This test was repeated on a similar engine, fitted with a standard Bentley camshaft, EB.316, and still a slight increase was shown at the peak, though power fell off very slightly at 4500 R.P.M. Test No. 2. Carbs. between cylinders 1 and 2, 4 and 5, distribution quite good. Centre cylinders slightly weaker at top speeds. At 500 R.P.M. full throttle, slight signs of gas singing in the pipe from end to end. This effect is only noticeable at this speed, running open exhaust, and an improvement should result from the better hot spotting of the proper SpectreCodename for Phantom III induction system. It should be pointed out that the 1.375" bore pipe has no balance restriction in the centre. When the restriction is removed from the standard Bentley induction pipe, gas singing is much more noticeable, and considerable ramming effect is lost. | ||