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 effects of a restricted exhaust baffle on engine performance and cooling system temperature.
| Identifier | ExFiles\Box 24\5\ Scan034 | |
| Date | 30th April 1925 | |
| R.R. 493a (50m) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -2- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}/LG30.4.25. 25 m.p.h. was maintained by varying the throttle opening. It was noted that, due to the fall in power occasioned by back pressure when the exhaust baffle was closed, a much greater throttle opening was required when climbing in this condition than with an un-restricted exhaust. The results shewed that the finishing temperature of the water system with the baffle fully closed was 7º higher than that with the baffle open. In these tests it will be observed that the load and engine speed were kept constant, the throttle opening a varied. (C) A further test was carried out to estimate the effect of a fully closed exhaust baffle on the car under average touring conditions. It was found that for a road speed of 40 - 45 m.p.h. the restricted exhaust caused a rise of 7 to 10ºC in the average temperature of the cooling system. It will be noted that all these preliminary tests were carried out to estimate the effect of extreme conditions, that is, the exhaust baffle fully closed with considerable throttle openings, a state of affairs which should never be approached on a normal car. A final road test was conducted in exactly the same manner, only in this case the exhaust baffle was coupled to the accelerator pedal instead of being fully closed. To ensure the worst normal conditions, the exhaust baffle was set to open from 0º to 65º for the full accelerator travel. This was considered to be the worst setting likely to be found on a car. contd :- | ||