The purpose of the present research is to determine the method of injection, injection pressure, starting period of injection and compression ratio, favourable in the manifoldinjection engine, and also to investigate the anti-knock characteristics and to compare them with those in the carburetor system. With the manifold-injection engine, the direction and the shape of the fuel spray, injection pressure, and the start of injection have not too serious effect on performance as in the cylinder injection engine. Especially, when the spray is directed against the air-flow, very low injection pressure (even 10 atm) can be applied. The start of injection of 90-120°after TDC on the suction stroke is optimum. Manifold-injection is superior to carburetion with respect to anti-knock characteristics. In the manifold-injection engine, slightly later spark is favourable than in the carburetor engine.
