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).
Performance analysis comparing the standard and cast aluminum expansion box silencer systems for the Phantom II.
| Identifier | WestWitteringFiles\U\January1930-April1930\ Scan037 | |
| Date | 13th January 1930 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/ACL. c. to EG. Wor.{Arthur Wormald - General Works Manager} c. to DS. E.{Mr Elliott - Chief Engineer} c. to EV.{Ivan Evernden - coachwork} X7230 X7771 PHANTOM II SILENCERS - COMPARISON OF STD. SYSTEM WITH CAST ALUM. EXPN. BOX SYSTEM. We have made an analysis of the losses of the Std. silencer system also the new system having the cast alum. expansion box and cast front end to the silencer. The analysis took the form of running the engine first with the complete system - cut out open and shut - then removing the swan neck, then the silencer and finally running with open exhaust. These results are plotted on prints V.{VIENNA} 765 and V.{VIENNA} 766. With cut-out closed the power output is the same as with each silencer system, giving a maximum of 110 B.H.P. at 2500 r.p.m. The present Std. system however shews an advantage over the cast alum system when run with cut-out open but the gain is only about 2% which considering the usual small amount of time the car is used with open cut-out and the actual small loss there would be no appreciable difference on the road. The reason why the cut-out open figures are slightly inferior with the cast alum system is apparently due to the smaller intermediate pipe between the front expansion box and the silencer. The pipe is 2 1/4" dia., instead of 2 3/8" inside which is used on the Std. system. This makes no difference with cut-out shut. The cast alum system was tested with a 2 1/4" dia. down | ||