Technical memo outlining required improvements for 25HP and 45HP car models.
| Identifier | ExFiles\Box 5a\1\ 01-page213 | |
| Date | 7th September 1931 | |
| HS. {Lord Ernest Hives - Chair} FROM E. {Mr Elliott - Chief Engineer} C. to SG. {Arthur F. Sidgreaves - MD} WDR. BY. {R.W. Bailey - Chief Engineer} X 5870 R3/MS.9.31. Sent off 7.9.31. CAR WORK. X.3993. X.5770. X.7770. A few things we must have quickly: (1) 25HP. & 45HP. BALANCE WEIGHTS. Balanced crankshafts partly at least preferably hardened. Present stock forgings waiting for WW. (2) 25HP. & 45HP. PROPELLER SHAFTS. HS. {Lord Ernest Hives - Chair} says my J. {Mr Johnson W.M.} 1. still suffers from the propeller shaft being too small in dia. therefore we want these of sufficiently large dia. I understand P. 2. is quite satisfactory, and the larger one already on 'China(Experimental Engine)'. (3) 25HP. & 45HP. RADIATOR COOLING. The deated tubes and non-spilling valve are very good moves. Means of allowing air to escape from under the bonnet must be carried out effectively, even to using the most effective louvres, but I hope our standard will be '31' type shutters even if 4 or 5 per side are needed. This is important and urgent. I want what is our standard on the 25HP. Continental tourer that I am to use, but sincerely hope for shutters because of noise and cold weather. I am definitely against the smaller fan dia. tubes because it means greater heat under the bonnet, and small benefit for the great cost and weight. MOTTO: Let air freely in and out. (4) 25HP. & 45HP. PERFORMANCE. I have given our views in another memo. I am just a little afraid of loss of silence etc from the higher valve lift, but this high lift seems very effective for high rev: performance, and we have suggested slight modifications to cams and rockers as a compromise. We seem to have got to the limit of valve timing, including overlap. Perhaps the inlet could close a little later and exhaust open a little later, but the cam length of 47 and 61 div: seems about right. E thinks we should go to greater acceleration than we have on 25HP. cams. We have on some cam forms this last 2 yrs. - .0045 [Diagram text] 6.5 I 50 E 50 15º of overlap (5) CARBURETTERS. The S.U. horizontal is nearly good, but lacks a few virtues that we think are necessary, and it would not be diplomatic to use this unless we are obliged. It will be | ||
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).