49 49 72______________________________________ note that the minimum average tension and unit pressure reduced the drag to such an extent that the friction between the piston and the cylinder did not measurably exceed the weight of the 5 inch piston a light unmeasurable pressure to overcome static friction resulted in the piston sliding by gravity through the cylinder comparative operational tests of the old and new types of oil rings together with regular compression rings in operating engines showed that oil consumption and blow by of combustion gases were approximately the same improvements in fuel economy of between 2 and 5 with the new rings were noted in additon to the immediate improvement in fuel consumption produced with the new rings other advantages of the new rings will be apparent the reduction in piston drag and friction will produce less heat so a smaller coolant pump and radiator may be used the reduction in drag will permit the use of a smaller and lighter starter all of these reduce the weight of the engine and will permit associated reductions in the weight of the car body note that reduction in the dimensions t and te reduce the depth of the grooves 18 so that the weight of the pistons may be reduced by enlarging their inner diameters behind the oil rings this.