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).
Comparison of performance between original and modified Spectre exhaust manifolds.
| Identifier | ExFiles\Box 93\1\ scan0013 | |
| Date | 7th February 1935 | |
| X323 To Sg.{Arthur F. Sidgreaves - MD} c. to By.{R.W. Bailey - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}22/KW.7.2.35. SpectreCodename for Phantom III Exhaust. Comparisons have been taken between the original exhaust manifolds to Lec.3793 and Lec.4184, which gives an improved sweep of the branches from the ports into the main pipe. There is very little difference between them, Lec.3793 losing 4 B.H.P. and Lec.4184, 3 B.H.P. from the open exhaust figure of 190 B.H.P. at 3750 R.P.M. the condition of open exhaust being a short separate pipe from each port. Below 3000 R.P.M., there is no measurable difference and no power loss to the open exhaust figure and actually at 2000 R.P.M. the manifolds are the better by 2-3 lbs/sq.M.E.P. These curves are shewn on B.P.10, being taken on No. 1 unit which has all whitemetal bearings, E.85255 camshaft and E.84546 semi-split pistons. Hs{Lord Ernest Hives - Chair}/L.H.Swindall. | ||