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).
The effects of raised exhaust valve guides on valve head temperatures in a B.80 unit.
| Identifier | ExFiles\Box 124\1\ scan0073 | |
| Date | 21th April 1939 | |
| -2- On the B.80 unit we have tried the effect of the raised exhaust valve guide bosses to PD.266, whereby the effective water cooling round the guide is raised by .250 nearer the valve head. So far as registered by the optical pyrometer as checked on two units, one with the lower guides and one with the higher guides, the valve head temperatures are very little different. To illustrate this we give the average figures taken at several speeds. TEMP. OF VALVE HEAD. R.P.M. Raised Guide. Low Guide. 3500 755° 740° 3750 760° 755° 4500 755° 770° Although the above two units had different camshafts, previous comparisons on similar shafts on the B.60 engine show that there is no power loss to the raised guide through restriction in the ports. Comparison of detonations show no difference between the raised guide and the lowered guide. Our conclusions from these tests are that whilst we cannot show any definite advantages of the raised guide there certainly are no disadvantages, and from a logical point of view there must be some cooling from the raised guides and that we should adhere to this feature. The optical pyrometer to register valve temperature is, we think, too dependent upon the operator and if we can find an alternative way of measuring the valve head temperature the tests will be repeated. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||