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).
Test report comparing the power output and noise of a new single downpipe exhaust system for the Phantom model against the standard system.
| Identifier | WestWitteringFiles\R\2October1927-November-1927\ 153 | |
| Date | 11th November 1927 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/ACL. c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} ORIGINAL Hs{Lord Ernest Hives - Chair}/ACL1/LG21.11.27. PHANTOM - SINGLE DOWNPIPE EXHAUST SYSTEM. X7830 Tests have been carried out on the test bench with the new single down pipe exhaust system LeC.2432/6/7 in order to compare it for power output with the standard system. The complete silencing system was employed in each case i.e. front silencer, rear silencer and fishtail - and tests were made with cutout both open and closed. As the test was made at full throttle the valve in the hotspot was shut, consequently preventing exhaust circulation through the hotspot. Appended are curves giving a comparison of the two systems. We find the new single down pipe system gives 9.75 HP. less than the standard at a speed of 2500 r.p.m. with the cutout open and 9.5 HP. less with the cutout closed. The new system is definitely noisy on the car compared with the std. possessing rather a metallic note. We think this may be due to the gases impinging on the bottom of the front silencer after passing the venturi. We have also experienced trouble with the hot spot valve sticking in the open position. With this hot spot valve fixed in the full open position - permitting full circulation of the exhaust through the hot spot - the maximum power was reduced by about 2.5 HP. Provided this were the only loss we see no reason, at the moment, contd :- | ||