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).
Analysis of an engine's smoothness, crankshaft, and connecting rod dimensions compared to competitors.
| Identifier | ExFiles\Box 173\2\ img086 | |
| Date | 23th February 1934 | |
| -2- However, in actual practice it was indistinguishable in smoothness from the 8 cyl. up to 60 M.P.H. Above that speed roughness could definitely be felt on the gear lever as on our own cars, but there was otherwise little evidence of it in the driving seat until 4000 R.P.M. had been attained. The master crankshaft period seemed to begin at about 3400 R.P.M. allowing for speedo error etc., but the valves floated before this. The intake and exhaust silencer was probably not quite so good as on the eight and the fan was noisy, but the impressive feature was the uncanny smoothness at speeds up to 60 M.P.H. The engine had a three bearing crankshaft. Naturally this interested me a great deal; the car sells at the same price as the Ford and Chevrolet over here: in other words, you can get one for about £130. I want to emphasise that my only interest in this automobile is in the power unit and gearbox, the rest of the car is just like the one at Derby. Analysing where the result is achieved - (1) Is it built in the Engine. Mechanically, one can see no reason why the engine should be particularly smooth. It has a three bearing crankshaft of quite normal dimensions except - Journal Bearings. Dia. Length. No. 1 2-11/32 1 1/4 No. 2 2-3/8 1 1/2 No. 3 2-13/32 2 3/4 Con. Rod. Dia. Length. 1-15/16 1 3/8 It is short between the bearings. Its overall length is 27.9", wt. 73.25 lbs. Its connecting rod is steel, certainly well pared down with a centre length of 6-3/16". The piston is exceptionally light, weighing 9.6 ozs. They have had to cut the skirt length I believe to miss the crankshaft, which is one reason it weighs so little, but it gives | ||