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 power tests concerning induction pipe depression with different carburettor setups.
| Identifier | WestWitteringFiles\Q\2April1927-June1927\ 3 | |
| Date | 21th April 1927 guessed | |
| contd :- -3- INCREASED POWER WITH LOWER INDUCTION PIPE DEPRESSION. Referring to the first set of results taken which are given on Print No.1. we have the power output with the std. cylinder head for the different induction pipe depressions given with the different carburetters. The full line curves are the power and corresponding induction pipe depression given with the standard RR. carburetter. A note on the induction pipe depression shewn here is necessary. Previous tests on the standard engine fitted with exhaust pipes and hot spot, the maximum induction pipe depression was 2.7 in.Hg. while in this case with open exhaust and no hot spot the depression was 3.5 in.Hg. This can be explained by the charge in the former case at a certain depression gaining heat from the 'hot spot' and consequently increasing in pressure thereby giving a lower depression than when running without a hot spot. The lower depression in the former case does not however mean any greater volumetric efficiency than with the higher depression. The other two curves shew the power improvement with one and two Zenith carburetters respectively. The reason for the curve with the single Zenith falling below the curve with the standard RR. at 1300 r.p.m. is due to the mixture becoming excessively rich. At speeds above 1750 r.p.m. the mixture was correct for maximum power. These carburetters were proportioned for feeding three cyls. which would account for the better metering when the two were employed. contd. | ||