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).
Analysis of the causes of unequal fuel distribution in a six-cylinder engine, discussing torque and running issues at low speeds.
| Identifier | ExFiles\Box 32\5\ Scan209 | |
| Date | 16th February 1923 guessed | |
| contd:- -2- at low speeds. Torque very uneven up to 1000 r.p.m. and very slight variation of mixture strength gave erratic running. When heater was in action distribution was better but left hand cylinders were still rich. ANALYSIS OF ACTIONS CAUSING UNEQUAL DISTRIBUTION TO THE SIX CYLINDERS. There are probably only two primary causes :- 1. Inertia effect of the heavy fuel. 2. Interference of cylinders - both inlet and exhaust. Case (1) is greatly increased if fuel is very incompletely vapourised. For complete evaporation of petrol - approx. Hexane - it must be supplied with its latent heat which is roughly 144 B Th U's per lb. at N.T.P. If no external heat is supplied the L.H. lowers the temp. thus lowering the vapour pressure, consequently the fuel is precipitated. These heavy drops of fuel possess consider-able more inertia than the air. Case (2) will have little effect on distribution in the Marmon standard induction pipe. The firing order is 1 - 5 - 3 - 6 - 2 - 4 and it will be seen that owing to the formation of the pipe very little interference is likely to take place. Dealing again with case (1) :- The air supply may be taken as proportional to the √Si, where si is the instantaneous suction on carburetter contd:- | ||