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).
Road test results for a Continental 25 HP car comparing performance with different engine configurations and components.
| Identifier | ExFiles\Box 179\2\ img177 | |
| Date | 22th January 1932 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/ c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to S. Da.{Bernard Day - Chassis Design} c. to By.{R.W. Bailey - Chief Engineer} ORIGINAL Hs.{Lord Ernest Hives - Chair}2/W.22.1.32. CONTINENTAL 25 HP. CAR. X5120 We have now carried out a number of road tests on the 25 HP. with the throttle edge slow running and the 50% larger chokes. On the whole the difference in performance is disappointing. This is because the larger chokes give the most increase in M.E.P. above 50 M.P.H. whereas the major part of acceleration and hill climbing is done between 40 and 50 R.P.H. We have also had on the road a 'China' fitted with J.1 head and slightly longer duration camshaft. The J.1 head enables us to use appreciably high compression ratio than China without detonation. Actually, at 6.35 C.R. it is possible to accelerate from 10 M.P.H. at full throttle on Shell Mex fuel without 'pinking' when the head is clean. For the preliminary road tests we used a pair of S.U's. as on the 40/50. These give the same power as curve A.{Mr Adams} on Rm.{William Robotham - Chief Engineer}64. The carburetters to LeC.2924 as will be seen, give good power, but we have not yet got them to snap open satisfactorily with the 1.00" chokes. However, we are working on them. The performance of the 25 HP. with this head is outstanding. Referring to Curve RM.{William Robotham - Chief Engineer}64. Power increase over standard unit - Road Speed. Proposed Japan Continental Car. Inc. in Power over 18-G4. 40 M.P.H. 20% 50 M.P.H. 22% 60 M.P.H. 26% 80 M.P.H. 65% The three features of the J.1 head which produce this result are - (1) Useful compression ratio say .5 higher than China. (2) Two carbs. can be used which give 5% improvement in M.E.P. over a single carb. just where it is most wanted i.e. between 30 and 50 M.P.H. (See Rm.{William Robotham - Chief Engineer}P.45). (3) No loss of depression going through the block. We have only just been able to take full advantage of this with the various low depn. carbs. that we are using. | ||