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).
Technical comparison between Jaguar and Bentley components, including exhaust, frame, and engine performance.
| Identifier | ExFiles\Box 126\5\ scan0088 | |
| Date | 15th September 1938 | |
| -4- (1) The Duplex Exhaust System. The Jaguar has proved that a Duplex Exhaust System can be fitted without excessive cost or weight, and our own figures show that they have reduced the horse-power loss to the silencer very considerably by this expedient, and, at the same time, got a very quiet system. The information will be applied to our future Bentley sports car range. (2) We were told that it was possible to make a box section frame without a cruciform member which would be as stiff for the weight as our Bentley III frame. An analysis of the Jaguar frame has shown that this is not so, and that the Jaguar type of construction is 89% heavier for the same stiffness than our B.III design. It is also more expensive to produce. (3) Very short engine length for the displacement. We find that there is no mystery about the design of this short engine. In reducing its length they have cut down their bearing areas and also their power output. The actual measured power output of the engine is not quite so good as our 3½-litre Bentley. The fact that the Jaguar on the road gives a slightly better pick-up than the 3½-litre Bentley is explained by the fact that (a) it loses less power to the silencers; (b) it has a lower gear ratio; (c) the car is lighter. (4) We have repeated the Brookland tests, and these show that they sacrifice a certain amount of top speed by their lower axle ratio - Average 3½-litre Bentley lap speed = 87 " " Jaguar " " = 84 They must of necessity also sacrifice a certain amount of durability for the same reason. The engine is remarkably smooth, but how much of this is due to cast iron and how much to short length we shall not know until we have tested our own cast iron unit. | ||