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).
Engine pumping losses, exhaust valve performance, and results from motoring tests under various conditions.
| Identifier | WestWitteringFiles\L\July1924-September1924\ Scan43 | |
| Date | 1st September 1924 | |
| B.R. 403A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} -3- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/RM{William Robotham - Chief Engineer}/LG5.9.24. EXPERIMENTAL REPORT. be a probability of the air being mixed with exhaust gas. Owing to pumping losses, it was found impossible to get any power out of the engine with a higher scavenging pressure, otherwise this would appear to offer possibilities. The exhaust valve is of generous dimensions being 2.375" dia. but with a small lift, only .300". Its opening period is 174°. Its cam is peculiar in shape. Undoubtedly the valve, spring and cam would require re-designing for high speed work. From the excessive fuel consumption, which is over 1 pt/I.H.P.hr., one would be inclined to say that the exhaust valve closed rather too late, allowing mixture to be blown out. We did not obtain better results upon reducing the period by altering the tappet clearance, this, of course, inevitably reduced the lift and also delayed the opening of the valve. MOTORING TESTS. It was observed that at 500 r.p.m. the frictional and pumping losses of this engine amounted to 39 lbs/sq.in. M.E.P. An analysis was made of these losses by motoring the engine under the following conditions:- (a) As run at 500 r.p.m., scavenging 3 lbs/sq.in. (b) Same condition scavenging air pipe 'H' removed. (c) All valve caps and plugs removed. (d) Rotary valve bodily removed. The water jacket temperature was maintained at 80°c, if the temperature of the jacket was reduced at all, the motoring losses at once increased, confirming that the contd :- | ||