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).
Investigation into cylinder stud and gasket failures on a supercharged Peregrine engine for the 'Bensport' project.
| Identifier | ExFiles\Box 86\1\ scan0007 | |
| Date | 22th September 1932 | |
| 8219 To R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} c.c. Mr. Nor. Mr. Ev.{Ivan Evernden - coachwork} Mr. AHG. re Bensport. We find we are unable to maintain a good joint with a metal gasket on the supercharged Peregrine fitted with .25 dia. cylinder studs. As soon as we begin to get any boost on the engine the joint develops copious external leaks, and the gasket finally fails by burning. This is in spite of the studs being tightened down to the stretching point. It will be remembered that for the later Peregrine engines we have increased the stud size to 9/32" to overcome stretching in normal tightening, but we are confident that this move will not be sufficient to meet the requirements of Bensport. We have, therefore, made another investigation to see if .312 studs could be used without lengthening the engine and believe it can be done safely if the stud thread is buried sufficiently in the stud bosses between the cylinder bores. There are one or two small difficulties in connection with the head passages but these can be overcome. Unless we hear to the contrary therefore we are putting through instructions for the .312 studs which give us 50% increase in cross sectional area over the .25. The following figures compare Bensport and Kestrel cylinder studs, but do not take into account the different character of the cylinder head joint which would demand proportionately more stud power from the Bensport:- Engine. | Pressure area. sq.ins. | Area of stud section. sq. ins. | No.of studs per cyl: | Ratio-pressure area to stud area. | Ref --- | --- | --- | --- | --- | --- Kestrel | 20.629. | .1418 (stud waist) | 4 | 36.4. | A.{Mr Adams} | ||