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).
Pros and cons of a push rod engine for the Bensport car compared to an overhead camshaft engine.
| Identifier | ExFiles\Box 3\4\ 04-page028 | |
| Date | 8th April 1932 | |
| Sheet 2. The push rod engine was considered at W.W. for the Bensport and discarded because:- (a) For any given size of valve it does not give maximum performance. (b) The sparking plug position and cooling is not so good. (c) The maximum speed of the engine is more restricted by the point at which the valve gear commences to float. For continental road and track racing the central plug overhead camshaft engine is without doubt a necessity, but the question arises does not the push rod engine do practically all we want for Bensport, and possibly save us from forced participation in racing. It has already been demonstrated on both the 20/25 and P.II. that the push rod engine can be made to develop very high output. The question of sparking plug position is not so acute on a small cylinder as regards detonation. It is thought we could reach a maximum speed of 5000 with push rods since the 20/25 will run up to 4200, and one or two other engines such as the Talbot achieve very high speeds with pushrods. The Peregrine is geared to 17.5 m.p.h. at 1000. With less overall car weight, and the supercharger boost the Bensport might be geared up to 20 m.p.h. at 1000 in which case 5000 max engine speed would be sufficient. Besides being a simpler engine to build the push rod engine offers the maximum degree of interchangeability with Peregrine with corresponding advantages as regards production and at the time is all the while improving the breed of Peregrine. CONTINUED - | ||