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).
Overheating of engine oil in the Peregrine engine and the need for an oil cooler.
| Identifier | ExFiles\Box 131\1\ scan0090 | |
| Date | 29th March 1933 | |
| X4693. To Sg.{Arthur F. Sidgreaves - MD} from E.{Mr Elliott - Chief Engineer} c. Wor.{Arthur Wormald - General Works Manager} Hs.{Lord Ernest Hives - Chair} PN.{Mr Northey} By.{R.W. Bailey - Chief Engineer} E.4/HP.29.3.33. re Overheating of Engine Oil - Peregrine. Replying to your memo Sg.{Arthur F. Sidgreaves - MD}20/E.27.3.33, the Experimental department are still carrying out investigations comparing the heat to oil on the Bensport and Peregrine engines. It has been definitely established as regards Peregrine that when running at the maximum speed the heat to oil is sufficiently great to necessitate the use of an efficient oil cooler of some sort. The ribbed oil sump has not sufficient cooling capacity to deal with the quantity of heat to be dissipated. We have issued instructions experimentally for an air cooled oil cooler incorporated in the radiator behind the shutters. The oil cooler takes the place of a part of the matrix of the radiator which we have cut away, and which can be easily spared since the radiator is definitely too large. The question will naturally be asked why an oil cooler is necessary on Peregrine and not on Bensport. As soon as another J.1. engine is available the figures for heat to oil on Bensport will be taken, but at the moment we know that the peripheral speed of the main bearings on the Peregrine is definitely higher than on the Bensport since the crank journals are the same diameter. Two thirds of the heat to oil, we know, arises from heat generated in the bearings, big ends, etc. the remaining third being derived from splash on the pistons. We also know that any increase in engine speed increases the heat to oil more than in direct proportion. The Bensport engine also has more capacity for dissipating heat from the crankcase than has Peregrine. We think we have got to face the fact that the more we increase the speeds of our chassis engines the greater will be the necessity for oil cooling. Daimler's have fitted a cooler for some time now to most of their models, incorporated on one side of the radiator, and we can well understand that | ||