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).
Various power loss experiments conducted on a Bentley engine.
| Identifier | ExFiles\Box 3\6\ 06-page289 | |
| Date | 29th October 1934 | |
| x4553 29.10.34. Various Power Loss Experiments on Bentley. The object of these experiments was to find what losses we might expect through induction restrictions with our latest engines giving a higher output than the present standard engines. The unit these tests were carried out upon was one giving a higher output than the engines we expect to standardise shortly, the compression ratio being 7.4: 1. In order to again verify that the larger inlet did give improved power output we compared the 1.450 dia. valve against the 1.500 dia. valve both with and without the air silencer. The cylinder head fitted to the unit had originally 1.450 dia. valves and we at first intended to vary the size from 1.400 dia., the present standard, up to the proposed 1.500 dia., but there was such a definite increase in power by using the 1.500 dia. valve over the 1.450 dia., that we did not think it necessary to try the 1.400 dia. valves. The 1.500 dia. valve is definitely better both with and without the air silencer as shown on curves B.V.53 and 54. The gain with the air silencer fitted is not quite so great at speeds above 4000 r.p.m. as the gain at these speeds with the air silencer removed, so that we centred our attention on the air silencer in order to find what power loss we should expect and where the loss occurred. Curves B.V.55 & 56 show the power losses with the complete air silencer and with two different sizes of intake "Bends". The larger bend as can be seen from the curves does not increase the power over that given by the standard bend at high speeds, and this holds good with both the air silencer fitted and with the air silencer removed. The larger bend, however, gives a slightly increased power output over the standard bend at 2500 r.p.m. and this is probably due to better "Ramming" effect with the larger bend. | ||