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).
Experiments to increase engine power by modifying carburettor and intake dimensions.
| Identifier | WestWitteringFiles\R\2October1927-November-1927\ 81 | |
| Date | 11th November 1927 guessed | |
| contd :- -2- For the next experiment the choke was completely removed and a bell mouth entry added to the intake side as shewn in the adjoining sketch. The depression in the uptake pipe was unaltered shewing that in this case the limiting factor was the dia. of the uptake pipe. The experiment proved that in order to get a depression as low as one inch at this speed we should have to increase the dia. of the uptake pipe. A larger carburetter was next used having a 2.5" in dia. throttle and the choke 2.062" dia. the free choke area was therefore 2.95 sq.in. or 60% of the throttle dia. area. The uptake pipe was also increased to 2.5 in. dia. With the above mentioned dimentions a depression of 1.00 in. above the throttle and 1.70 in. at the choke resulted at 3000 r.p.m. The power output was 120.4 B.HP. or 68 lbs/sq.in. B.M.E.P. Considering the low depression the power results are considerably below that we hoped to obtain. We find however that with the std. 4.1 to 1 compression ratio - which was used for all these tests - this is the highest power we have recorded at this speed. Double valve springs were fitted for these tests to ensure the valves did not bounce at the high speeds. The previous highest power recorded at 3000 RPM was 116 B.HP. with two Claudel (Eagle Vlll ) carbs. contd :- Text from diagrams: Sketch 1: 1.6 DIA Sketch 2: 2" DIA, .7" DIA, 3.750 DIA | ||