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).
Summary of experiment results on the 'Japan' engine, focusing on twin carburetters and a long duration camshaft.
| Identifier | ExFiles\Box 6\7\ 07-page092 | |
| Date | 23th August 1931 | |
| -4- The Very appreciable gain possible with twin carburetters and 112° long duration camshaft. The results of our experiments on 'Japan' can be summarised as follows :- (1) Twin carburetters give a very definite gain in power over the whole speed range. The max. B.M.E.P. occurs at a useful speed of about 35 M.P.H. Max. B.M.E.P. 119 lbs/sq.in. with 5.25/1 compression ratio and 100 lbs/sq.in. at 3000 R.P.M. (open exhaust). (2) Long duration cams with 112° between cams give excellent results with the twin induction system. This is the best differing camshaft which has for inlet cam the old std. exhaust cam and longer duration exhaust cam. (3) The small bore 1.25" dia. induction system gives excellent distribution and is better for power than the larger sizes tried. (4) The small patch hot spot appears very effective. No 'loading up' evident. Engine very responsive to throttle. So far we have not experimented with the metering of the carburetter but now we are working to obtain economical metering and good general running operation. We propose to transfer the engine to a chassis and make the carburetter the best we can for road work. We shall then be able to compare the performance of this engine with the std. chassis also make consumption tests to determine the best economy we can expect from twin static carburetters. HA/ACL. | ||