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).
Comparison of oil consumption and blow-by between cylinder blocks machined whilst on the crankcase versus those machined in the normal manner.
| Identifier | ExFiles\Box 132\4\ scan0104 | |
| Date | 19th October 1937 | |
| -12- Rm{William Robotham - Chief Engineer}/mths.{Reg Matthews}B/H.W.19.10.37. of a cylinder block machined whilst bolted to crankcase by means of a 'dummy' cylinder head and in which the distortion was thereby cut down to a minimum. Curve (2) shows the figures obtained with a standard block produced in the normal manner. There are two possible reasons for the fact that the block machined on the crankcase is worse than the standard block. (1) As shown on Fig. X the blow-by is much worse than with the standard block. (2) By having a true bore, piston clearance on the skirt is changed & modified bedding may become necessary. Ring Flutter. Fig. X shows a curve of variation in blow-by with engine speed, curve (1) shows the blow-by with cylinder block machined on crankcase, as this curve shows, blow-by above 4000 r.p.m is considerably more than with the block machined in the normal manner (curve (2)). FIG. IX BENTLEY OIL CONSUMPTION TESTS. AEROLITE PISTONS. MOTORINE 'C' OIL. PRESS 30 LB/SQ INCH ① CYLINDER BLOCK MACHINED ON CRANKCASE. ② NORMALLY MACHINED BLOCK. OIL CONSUMPTION (PTS/HR) HRS: RUN. MTHS{Reg Matthews} 19.3.37 FIG. X BLOW-BY CURVES. AEROLITE PISTONS STANDARD RINGS ① CYLINDER BLOCK MACHINED ON CRANKCASE. ② NORMALLY MACHINED BLOCK. FULL THROTTLE. BLOW-BY (CU FT. / MIN) R.P.M. MTHS{Reg Matthews} 19.3.37 | ||