OILING FOR HIGH SPEED

NZ Truth, Issue 1199, 22 November 1928, Page 20

OILING FOR HIGH SPEED

Problems In Lubrication For Gar Owners

T ÜBRICATION of engines running" at high speeds, as m racing 1 , is a problem m itself. Not only must a really good oil be chosen, but its provision insufficient. quantity at the points of greatest heat and pressure is just as important.

IN most / modern cars, and many motor- cycles, the oil is supplied under pressure !to the big-end bearings, being sprayed thence by centrifugal action to the other parts. In all engines such parts as bearings and piston' 'tire cooled mainly by transfer of heat to the oil, and to get rid of this heat the sump should have a good area exposed to the air for cooling. Further, the sump should be kept as clean as possible to facilitate cooling. In a few car engines the oil is circulated through a special radiator and efficient oil cooling is achieved m motor- cycles using' the dry sump system by constantly changing the oil. On many motor-cycles oil mist is relied upon for lubricating the timing gear, but where really high speeds are to be attempted, a direct supply of oil may be available to

secure thorough cooling of the cams and bearings. ; Overhead valve gear is best totally enclosed and oiled by mist from the crank-case, but adequate lubrication of the valve stems can be secured only by the use of upper cylinder lubrication \yith some special high flash-point oil such as Firezone, which also materially aids m maintaining compression and lubricating the piston. As regards the main oil supply, pure castor oil is unsuitable both by reason of its gummy consistency when partly burnt and the acidity which develops. Both these faults are overcome by blending it with- about 10 per cent, of other oils. ' Though it may not possess quite the resistance to heat and pressure, of compounded castor oil, really high-grade mineral oil is quite suitable for most racing engines.