New Sound on the Circuits A Lotus 23 powered by Ariel Arrow - Six of them! by JOHN BOLSTER To the mechanically minded, the tendency to use only a few makes of engine in racing must somewhat reduce the interest nowadays. The new Rotorvic will therefore be of considerable interest. This car designed by R.V. Marchant and driven by Bill Hill, has a Lotus 23 sports-racing chassis, modified to take the unusual engine. This consists of no fewer than six Ariel Arrows, making in effect a 12-cylinder two-stroke engine of 1482cc. The air-cooled power units are inclined outwards at 45 deg., giving an angle between the cylinders of 90 degrees. Each engine has a straight-toothed pinion on its mainshaft which engages with a similar pinion on a shaft which runs down the centre of the engine. These gears are enclosed in housings and the shaft has a flywheel on its end, which carries the single dry plate clutch and drives the ignition system by toothed belts. The transmission is via a Hewland five-speed gearbox. Lubricated on the petroil system, the engines are at present cooled by air collected in large scoops, though a Porsche-type fan may be an eventual solution. The whole assembly is installed in a most workmanlike manner, a starter ring being arranged on the flywheel as push starting on the grid is now forbidden. The car is in its early stages of development but already shows promise. The exhausts are arranged to collect three cylinders apiece into four separate megaphones, and the shape of these ducts will be the subject of elaborate experiments. Though eventually 10,000 rpm will be exceeded, at present the machinery does its best work at 7500 rpm. Seen in action at Snetterton, the Rotovic travelled at a good speed and made a splendid sound. Apart from the fierce note of the 12 two-stroke cylinders, there is little mechanical noise, in spite of all those pinions. It is difficult to tell if one or two cylinders are "out," but an ingenious system of thermocouples will indicate by lamps on the instrument panel if any of the exhaust branches are not maintaining working temperature. Listen for a new sound on the circuits!