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).
Further tests conducted on a Peregrine engine to reduce heat transfer to the oil.
| Identifier | ExFiles\Box 131\1\ scan0113 | |
| Date | 16th June 1933 | |
| X 4693. To Sg.{Arthur F. Sidgreaves - MD} from Hs{Lord Ernest Hives - Chair}/An. c. E.{Mr Elliott - Chief Engineer} Wor.{Arthur Wormald - General Works Manager} c. Ey. Da.{Bernard Day - Chassis Design} HEAT TO THE OIL. We have carried out further tests on Peregrine with a view to reducing the heat given to the oil. There are, as we have previously pointed out, certain difficulties in measuring heat to the oil on the test bed. The figure actually obtained is the B.T.U's given to the oil less those dissipated by the bottom half and the engine. It is therefore clear that unless the inlet oil temperature is considered in conjunction with the B.T.U's figure given, the latter does not mean anything. As an example, Curve 4 indicates that if the oil inlet temperature was 110ºC. at 3500 r.p.m. the whole of the heat given to the oil would be dissipated by radiation and convection. Therefore for comparisons, an arbitrary figure of 80ºC was used for the oil inlet temperature and was kept constant for all tests. In every case all the oil circulated by the pump was ultimately drawn into a small tank underneath the engine, and therefrom into the system again. None of the figures given are intended to indicate the difference between the ribbed and plain sump, in still air the margin between the two is probably less than the experimental error in taking readings. We think that the main facts emerging from this series of tests are :- (1) That passing a large quantity of oil round the tappet cover and so into the crankcase is responsible for an increase of about 30 B.T.U's/min. or 12%, heat to the oil at 4500 r.p.m. or a road speed of about 75 m.p.h. Since the temperature of the cylinder block is the same as the water temperature which was maintained at 80ºC - i.e. the inlet oil temperature - the oil going into the tappet cover cannot pick up heat from the cylinder block. We think that the 30 B.T.U's therefore are mainly caused by the increased quantity of oil being thrown on to the pistons by the crankshaft. (2) The bottom half is a better cooler in still air when it is empty than when it contains one gallon of oil. This in a way is obvious because when there is a gallon of oil in the sump it must have a stagnant layer preventing the hottest oil from reaching the aluminium. | ||