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When the power or specific fuel consumption is estimated in design process, thermodynamic consideration for the estimation is generally insufficient. Hence, a theory that can estimate these performances accurately is investigated in this paper. As a result of investigation, it is clear that the effect of pumping loss in wide-opene throttle valve operation has to be excluded from the mechanical loss which is measured in the motoring test. It also becomes clear that a new coefficient called pumping loss coefficient ηP has to be considered for the negative work for pumping. From the foregoing, theoretical formulas for estimating the net power Pe and net specific fuel consumption be. which are formed with various efficiencies and coefficients are as follows: It is verified that the estimation from these formulas agree well with the experimental test values using stoichiometric mixture ratio.

In the stratified charge engine with an auxiliary chamber, the time required for combustion in the main chamber is considered to depend upon the characteristics of the turbulent jet-flame propagating in it. This study has been conducted to explore the controllability of the time required for combustion by changing the characteristics of the turbulent jet-flame. Experiments were performed by using a constant volume combustion chamber which was divided into a primary and a secondary chamber by an orifice plate. The characteristics of the turbulent jet-flame were changed by changing fuel, mixture strength and hole size of the orifice plate. The experimental results indicate that the time τ required for combustion in the secondary chamber mainly depends upon the jet-flame velocity VF (propagation velocity of the leading front of the jet-flame) and the mixture strength Φ.

The major features of the stratified charge engine with an auxiliary chamber are: (1) the mixture in the combustion chamber has concentration gradient due to the auxiliary chamber and (2) turbulent flame is injected into the main chamber. The objective of this research is to examine those effects upon the combustion characteristics and the burned gas composition. The characteristics of flame propagation were examined by using a series of schlieren photographs. A summary of the major conclusion of this research is given below: (1) The mixtures supplied in the main and the auxiliary chambers burn without mixing with each other. (2) The concentrations of HC and CO decrease as the closer the mixture in the auxiliary chamber approaches stoichiometry and the leaner the mixture in the main chamber.

To evaluate and optimize multi-cylinder engine performance (output, fuel economy, exhaust gas emission, vibration, etc.), it is necessary to clarify the quantities of air and fuel distributed to each cylinder according to the engine speed and the carburetor throttle opening, and to clarify the correlation between the above characteristics and the engine performance. From this point of view, some "survey" fuel with a known quantity was supplied to the position just in front of the intake valve of each cylinder of a provided test engine to obtain the distributed quantities in each cylinder from the changes of air-fuel ratio at that time, and the accuracy of this method was studied accordingly.

An important advantage of the 2-stroke cycle gasoline engine is that its emission of NOx is very low. Experimental models of this engine showed that its percentage of exhaust gas contaminants could be made sufficiently low to meet the specified 1976 standard. Proper control of gas flow into the cylinder produced smooth combustion at idling. Thus, in the experimental model described in this paper, the usual draw-backs of the conventional engine (vibration, noise, knocking) have been eliminated so that vibration, power output, and fuel consumption are comparable to those found in a 4-stroke engine, without using an exhaust treatment system.