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).
Testing an annealed Goshawk cylinder head for cracks under severe boiling conditions.
| Identifier | ExFiles\Box 24\4\ Scan063 | |
| Date | 11th July 1922 | |
| To R.{Sir Henry Royce} from HS.{Lord Ernest Hives - Chair} c. to CJ. c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} X.1751. X766 HS{Lord Ernest Hives - Chair}6/LG 11.7.22 GOSHAWK CYLINDER HEAD X.4225. X.1751. X766 We have tested an annealed Goshawk cylinder head. The effect of the annealing was to reduce the brinell from 200/210 to 150/160. This head was fitted to an engine and the car was run under boiling conditions until it was obviously short of water. In one case it was run 36 miles boiling and in another it was run 33 miles boiling. We found on examination that there were cracks across the exhaust valve seatings but there were no cracks to cause external water leaks. It would appear that although the annealing may have affected an improvement in preventing the external leaks, it is no definite cure against cracks on the exhaust valve seatings. Our tests, of course, are very severe - it means that at the final stages the engine is practically run without water but it is only when nearly the whole of the water is used up that it is possible for the average driver to notice any signs in the running which would tell him that the engine was overheated. Undoubtedly, what saves the 40/50 in a number of cases is that as soon as there is any loss of water or even when it boils, the engine commences to detonate badly and so make it obvious to the driver that something exceptional is happening. We have carried out one test with the cylinder head fitted with three water outlets and larger diameter top pipe instead of the standard arrangement. We have not been able to measure any contd:- | ||