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).
Lack of expected performance from a new 20HP turbulent head and requesting further investigation.
| Identifier | WestWitteringFiles\T\March1929-December1929\ Scan092 | |
| Date | 22th April 1929 | |
| SECRET. ORIGINAL SG{Arthur F. Sidgreaves - MD}: FROM R.{Sir Henry Royce} NR1/M22.4.29. REC'D AT WW. 25.4.29. C. to HCR. HS.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} E.{Mr Elliott - Chief Engineer} PN.{Mr Northey} C. EE. 20HP. TURBULENT HEAD ETC. X5050 X5770 +790 I am somewhat surprised that no definite improvement was found between London trials car and G.4. One can only think there is some quite remarkable advantage in both power and smoothness between a well run in chassis (really engine) and a somewhat raw one (i.e. the production twenty's do better HP. after being in use some time.) We do not expect much from the head alone. It was only thought to have the advantage of being less liable to detonations, and so possibly enable an increase in compression ratio. We have not I believe increased the compression, but rather left the engine safer from detonations. We have with the new head such an improved inlet and exhaust system that unless we have done something wrongly we expected the engine to fill up better, have better distribution, and that more HP. would be obtained. Also we should get two other improvements - i.e. good cold distribution (starting away quickly cold), and also no explosions in the exhaust. Moreover I have before me memo. HS{Lord Ernest Hives - Chair}/ACL/28.3.29., a report giving - @ 2500 revs. an increase of over 11 HP. in 48 - really 26%. It cannot be possible that this has no effect, and it is difficult to believe it can be masked by the difference of a free running engine. Moreover I cannot believe that Mr. Hives and Mr. Platford would leave Derby with a car that gave no more HP. on the test bed or dynamometer than the present standard twenty's. Perhaps in addition to the free running in, the body was different, either heavier or greater windage, or the engine revs. were so high that the valves were jumping. Will E.{Mr Elliott - Chief Engineer} telephone HS.{Lord Ernest Hives - Chair} this message and wire me some results. We cannot also understand a rougher engine unless mechanically tight, or more power, because the compression ratio is the same. R.{Sir Henry Royce} | ||