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 on Induction Pipe LeC.3637 and a 1 5/8' S.U. Carburetter for a 25 HP Type Cylinder Head.
| Identifier | ExFiles\Box 103\4\ scan0111 | |
| Date | 7th March 1934 | |
| X5050 7.3.34. Tests on Induction Pipe LeC.3637 and 1 5/8" S.U. Carburetter for 25 HP Type Cylinder Head. We have recently completed our tests on the above Induction Pipe with results as below. The conditions under which we have tried this pipe are :- (1) As shown on LeC.3637 with water hot spot. (2) As shown on LeC.3637 with adjustable amount of hot spotting. (3) With pipe turned over from end to end and 1 1/2" long distance pieces between pipe and cylinder head so that level of pipe was above level of ports in head instead of below. (4) Throttle valve opening away from carburetter. (5) Throttle valve opening towards carburetter. Under all the above conditions the distribution was very poor and maximum power was obtained with the throttle partially closed and with very rich mixtures. The attached power curve No. 1 shows the best results obtained with this pipe and refer to conditions (1) and (5) above. Tests were also made with a 1 3/8" S.U. carburetter on this pipe but it was found to be of insufficient capacity for the engine. The piston of the carburettor reached the top of its stroke at 2750 r.p.m. full throttle and the petrol flow into the float chamber was inadequate for speeds above 3500 r.p.m. As the standard 25 HP. induction system gives good distribution a standard 25 HP+ pipe was modified as shown on Hs.{Lord Ernest Hives - Chair}1329 to take a 1 5/8 S.U. carburetter directly on the pipe. This pipe was tried under the same conditions as pipe LeC.3637 except that exhaust heating of the hot spot was not used. | ||