WONDERS OF ENGINE

Sun (Auckland), Volume IV, Issue 1078, 16 September 1930, Page 6

WONDERS OF ENGINE

ROLLS-ROYCE AERO Further and still more remarkable figures are now available relating to the Rolls-Royce Schneider Trophy engine with which fresh atttacks on the world’s speed record will be made very shortly. Per brake horse power developed the weight of this engine is 12oz. only, as compared with between Sib. and 101 b. for the average motorcar engine. Whereas the normal engine gives 38 b.h.p. a 100 cubic inches of cylinder capacity (or with a supercharger just over 40 b.h.p.), the RollsRoyce gives 90. In its standard form tills engine is designed to give 825 b.h.p., but ti c Schneider Trophy version delivers 1,900 b.h.p.! These factors contribute tp this:-—• (1) Alteration to almost everything , except the actual figures for the bore and stroke, which are Gin. and til in. respectively. (2) The fitting of a supercharge - the rotor of which does 32,500 r.p.m at full throttle. (3) The fitting of a form of airscoop, the effect of- which at neatly six air-miles a minute is very considerable indeed. Of these modifications probably the last; mentioned will be of most inter est to the enthusiastic owner-driver who has dften considered the possibilities of an air scoop, or. perhaps, has even tried fitting one in Ms younger days. The difiiculty is that on a car the direction and strength of the wind, relative to the air intake, is constantly varying. But in the case of aircraft the wind pressure is practically constant in. whatever direction one may be flying, and speeds are so much higher. Thus an air-scoop begins to have an appreciable super-chargine effect rr even 120 m.p.h.—and the Rolls-Royce 1 engined 5.6 has already accomplished three times that speed.