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).
Report page detailing the performance, modifications, and issues with a converted Vauxhall Ten engine featuring an Aspin rotary valve head.
| Identifier | ExFiles\Box 134\1\ scan0198 | |
| Date | 14th February 1944 guessed | |
| -2- The converted Vauxhall Ten engine, although designed by Aspin so far as the cylinder head was concerned, was also influenced by Alex Taub in that he was insistent that Aspin should attempt to use the conical surface of the rotor to take the thrust in place of the ball or roller bearings which Aspin had previously employed. Incidentally it is interesting to note that a similar arrangement is used in the latest Aspin Commercial vehicle engine. In our case it was by no means an unqualified success, as friction in the rotors resulted in a very low mechanical efficiency and also gave us trouble with the drive. There was a direct oil feed to each rotor and springs were used to maintain contact between rotor and head during the parts of the cycle where the pressure in the cylinder was sub-atmospheric. As received the converted Vauxhall engine had a compression ratio of 12.2 to 1 but owing to heavy detonation on pool petrol this was reduced to a figure of 9.6 to 1. The rotors were not water cooled. At the lower compression the engine just about managed to cope with 69 Octane petrol although there was considerable detonation at full throttle at speeds around 1600 R.P.M. At lower and higher speeds the engine ran reasonably well. Corrected figures for I.M.E.P. and B.M.E.P. at about 2,000 R.P.M., were 134 lbs/sq.in. and 100 lbs/sq.in. respectively. These compare unfavourably with figures of 140/145 lbs/sq.in. and 115/120 lbs/sq.in. which we normally expect from a Vauxhall Ten engine. The specific fuel consumption, which was adversely affected by the low mechanical efficiency, was about 0.7 lbs/B.H.P. hour. An air consumption curve was taken which was much the same as that obtained from a normal engine up to 3,000 R.P.M. but showed signs of exceeding our normal curve at higher speeds. I think that this engine was returned to Aspin for further investigation; anyhow we did no further work on it here and we soon became involved in the Churchill and other projects which kept us fully occupied. Early in 1940 we were also busy with Producer Gas and it was thought that an engine of the Aspin type might give good results on this fuel and might show a greater tolerance to impurities in the gas than does an ordinary poppet valve engine. For this investigation we used the single cylinder gas engine mentioned under heading No.3 above which had a compression ratio of 13.6 to 1. As a matter of interest we ran it on pool petrol but found that detonation made it impossible to approach full throttle. Auto-ignition was apt to occur after switching off. The rotor was fitted with a ball thrust race and the friction in the engine was reasonable but nevertheless we experienced a failure in the rotor drive. It is possible that this was partly due to the tarry deposits from the gas. A check run was made on undiluted benzole on which the engine could be P.T.O. | ||