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In order to reduce particulate and NOx emission from the direct injection diesel engine, most researchers have been expecting the utilization of higher injection pressure and injection rate for improvement of diesel combustion. In the case of pump-line-nozzle system, the injection pipe line is very important with regard to the high injection pressure. Namely, the pipe line must be able to resist not only high pressure but also cavitation erosion. In this paper, the effect of high injection pressure, injection rate and sharp cutting at the end of fuel injection are discussed along with cavitation phenomena on the injection pipe line. And durability tests on the pipe line system under high injection pressure using a test rig are also described. Regarding durability tests, several measures have been taken for the injection pipe. As a result, the authors have found that the best solution for the injection pipe is a composite pipe made with SUS and steel.

Experiments on a large number of soluble fuel additives were systematically conducted for diesel soot reduction. It was found that Ca and Ba were the most effective soot suppressors. The main determinants of soot reduction were: the metal mol-content of the fuel, the excess air factor, and the gas turbulence in the combustion chamber. The soot reduction ratio was expressed by an exponential function of the metal mol-content in the fuel, depending on the metal but independent of the metal compound. A rise in excess air factor or gas turbulence increased the value of a coefficient in the function, resulting in larger reductions in soot with the fuel additives. High-speed soot sampling from the cylinder showed that with the metal additive, the soot concentration in the combustion chamber was substantially reduced during the whole period of combustion. It is thought that the additive acts as a catalyst not only to improve soot oxidation but also to suppress soot formation.

Hino Motors, Ltd. has added to its line of charge-cooled engines for heavy duty trucks a higher power version which is called EP100-II. To meet the recent customers' demands for rapid transportation with better fuel economy, this engine was developed on the uprating program for the original EP100 which was introduced in 1981 as the first Japanese turbo-charged and air to air chrge-cooled engine. EP100-II has the same displacement as the original EP100, 8.8 liters, and is an in-line six cylinder engine with 228kW (310PS)/2,100rpm (JIS) output that provides the world's utmost level specific output of 25.8 kW (35.1PS)/ liter. Also this engine achieved a maximum BMEP of 16.8 bar/1,300 rpm and best BSFC of 199 gr/kWh at 1,500 rpm. This paper describes the advanced technology for increasing horsepower and improving fuel consumption such as the so-called multi harmonized inertia charging system, the electronically controlled waste gate valve of turbocharger.

A current unmodified and modified engines with different amounts of thermal insulation have been used to generate data from which changes in bsfc, cooling loss, emissions, exhaust loss were determined. Since legislative requirement exists for allowable emission of NOx, fuel injection timing and other controllable factors were adjusted to maintain constant NOx emission except a test of influence on NOx emission according to the rate of heat insulation (adiabaticity). The effect of higher combustion temperature on the combustion phenomena is discussed.

The purpose of the investigation presented here was to develop a high quality SAE 10W-30 engine lubricating oil to meet the heavy duty operating conditions of trucks. The operation of their engines is predicted to become more severe in future because of the trend toward higher power output, nore severe regulation of exhaust emissions and noise as well as the increasing demand for better fuel economy. To meet these demands, an improvement of the wear resistance of engine lubricating oil was considered to be the most important aspect for the development of high performance diesel engines in the future. The engine test developed was able to evaluate various experimental oils by observing wear resistance of the valve train which is considered to be one of the most severe tri-bological conditions. The best oils were determined by optimum selection of the amount and type of detergent, ashless dispersant and zinc dithiophosphate.

Fuel injection timing retardation for reducing exhaust emission of direct injection diesel engines prolongs the period to complete cold starting. Engine speed at this period varies through some accelerating and faltering stages. The speed variation and relating combustion characteristics was investigated through the measurement of cylinder pressure for each cylinder as well as the dynamic fuel injection timing and instantaneous engine speed. An improvement of cold start was shown by application of afterheat of a sheathed type glow plug and an electronic fuel injection timing control device.