TAPPET VALVE v. SLEEVE VALVE.

Press, Volume LXVII, Issue 14204, 18 November 1911, Page 9

TAPPET VALVE v. SLEEVE VALVE.

Much has boon said about the wonderful advantages of tho slocvo valvo engine* over tho tappet valve engine, lieecntly tho now (1912) 25-30 ! Sunbeam Car, with tappet valve engine, has accomplished a feat which no sleeve valve engine has ever attempted. Starting at 7.16 a.m. on September Ist, on Ikooklands track, tho car ran for twelvo hours, covering 907 miles, making an average speed, including atops to change drivers and wheels every two hours, of more than soventytivo miles per hour. Tho most extraordinary feature ol this trial was the amazing regularity of running. Quite 75 per cent, of the Inps were accomplished without 3sec difference in time, lap after lap being recorded approximately at 2min Bsee. Tho fastest lap was covered in 2min l-13th see. corresponding to a speed < £ approximately eighty miles an hour. In a test of this nature tho brunt of the work falls on tho engine; its small size, in view of the high speed attained by the car, indicates a very high engine speed. In fart, seventyfive njilcs an hour demanded an engine speed of ISOO revolutions per minute. The trial was not intended to be n test of human endurance, but of the capabilities of tho car to withstand hard work, and it was hard work to ■ keep an engine with a 90 m.m. boro land 100 m.m. stroke running for twelve hours pulling hard without n stop, at ISUO revolutions per minute: hut for tho uncommonly clever design and splendid construction it would have been impossible. It was at the end of the trinl that one could appreciate the roundness of the design. Taking the car at a whole, with tho exception of tho exhaust pipes, there was not a squaro inch of tho surface upon which one could not place one's hand. Tho / cylinders and bearings were at just that I temperature that makes the heart of j tho engineer rejoice and gives him tho I sntif-.faction of knowing 'that everything is working smoothly, efficiently, and up to his ideals. Also, that he "is justified in sticking to the tappet valve engine, which has proved its efficiency beyond nil doubr. J. S. Hawkes, LtdJ, Sole Agents for Sunbeam Cars, Royal Garage, Gloucester street, Christchurch. 7