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).
The performance testing of various exhaust manifolds for a 20 HP engine.
| Identifier | ExFiles\Box 6\7\ 07-page029 | |
| Date | 1st February 1928 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/ACL. c. to BJ. WOR.{Arthur Wormald - General Works Manager} STOCKFORDS. E.{Mr Elliott - Chief Engineer} c. to GA. BY.{R.W. Bailey - Chief Engineer} V5230 Hs{Lord Ernest Hives - Chair}/ACL1/L024. 2. 28. 20 HP. EXHAUST MANIFOLDS. In our previous report on the power output with the various exhaust manifolds on the 20 HP. we find that one of our diagrams was wrongly numbered. The best manifold tested was the three branch type as shewn in our sketch which we called Sch.935 but is actually Sch.934. Appended to the curves giving the power output with these manifolds is a print shewing the form of manifold with their correct scheme numbers which correspond with the power curves. We have noted the sketch of the Mercedes (memo. Rl/M31.1.28) exhaust pipe and should expect this scheme to be good for power. For some considerable time we have been running a 20 HP. with an exhaust scheme similar to Sch.934 and this car gives a very good road performance although it cannot all be credited to the exhaust manifold as this engine has the cyl. head with the larger valves which we used for our test bed investigations. The power output with the complete silencing system including swan neck and fish tail amounted to an increase of 3 1/2 HP. or 7 1/2% at 2750 r.p.m. over the standard manifold. This is not a particularly great increase because with low loss manifolds more of the work is transferred to the silencer. We have also observed that manifolds which give low power loss run appreciably cooler | ||