1. Overview
l Power (Kw / l):
reflect the level of quality is mainly to see the engine power and economy, that is to have a good engine power, good acceleration and lower fuel consumption.
Factors affecting engine power and fuel consumption, many of them have the greatest factor affecting the displacement, the compression ratio, valve means. But this is only refers terms. DETAILED comparison to the engine, due to differences in the use, design, materials and manufacturing processes, often resulting in significant differences.
There are some large displacement engine power is not necessarily smaller than the displacement of the engine power, for example, to compare the displacement, 2.0 liter engine car A maximum power of 97 kilowatts, car B is 2.2 liter engine maximum power may be only 79 kilowatts. Similarly, some of the same car emissions, the same 2.0-liter engine but the output power is not the same. Therefore, it creates a measure called “or power.” Engine crankshaft output-based indicators, said an effective indicator, this index represents the level of overall engine performance. Effective indicators include effective power, effective torque, or power and the like. Generally thought, power and torque of these two indicators will reflect the merits of the engine, it is not. Power and torque than the larger the engine, the better, truly reflect the engine’s power indicator is the power emitted per liter of cylinder capacity, that is, “or power.”
2, specific measures
l represents the power cylinder capacity utilization of the unit, or power unit said that the greater cylinder capacity power emitted. Then, when the engine power is constant, the greater the weight efficiency or power of the engine is higher, relatively smaller engine, the more it saves material. Quality engine design and manufacture of high and low rise reflected power. Since power is the product of L (N) is mainly determined by the size of the cylinder mean effective pressure (P) and speed (n), i.e., N= (P) × (n). L will increase the power and start from the cylinder pressure increase speed, so the specific measures to improve the power it liter are:
(1) increase the amount of inflator. This is the first condition of the four-stroke engine to increase the heat, because the fuel required for combustion air, fuel and air, the latter is more difficult to charge into the cylinder, it is necessary to improve the ventilation conditions, to reduce the intake resistance increases the cross-sectional area of the valve channel, some 4-valve engine to use form. When the multi-valve structure disposed difficulties, first of all to meet the needs of the intake valve, regardless of how to form a valve arrangement, the number of intake valves is greater than or equal to the number of exhaust gates.
(2) increasing the rotational speed to increase the amount of inflator unit time. Now car engines are generally high engine speed, rpm 5000 rpm or more.
(3) improve the quality of mixed gas and combustion processes. Electronically controlled fuel injection system, the highest possible quality in all conditions of the gas mixture from the optimum nature, place mixing air and fuel from the injectors to move the throttle valve, the fuel-air mixture directly inhaled, improving the uniformity of air-fuel mixture.
(4) to increase the engine output to increase the mechanical efficiency of effective work, mainly to reduce mechanical losses reduce the friction between the parts, the parts related to the processing accuracy, surface quality, the quality of lubrication, temperature control and reducing accessories.
here noted that the multi-valve structure and the maximum difference between 2-valve design is complicated multi-valve gas distribution structure, increasing valves, catheters, camshaft rocker arms, but also some special an increase in the camshaft, i.e., double overhead camshaft (DOHC), these additional devices necessarily increases mechanical loss. Therefore, some manufacturers still pragmatic 2-valve design employed in small and medium automobile engine. These four points are related to each other, for example each cycle of the engine rotational speed the higher the inflator to reduce the problems caused by the more prominent, it is necessary to adopt measures increased passage sectional area of the valve, increase the diameter of the intake valve head or multi-feed valve forms. However, the form of multi-valve will involve problems to the mechanical efficiency of the engine. Things in the world are always contradictions coexist, factory engineers how to adjust the balance, try to improve handling of contradictions, is reflected in the performance of the various engine.
and through the south field Alto GLOW liter capacity belonging to a class of the smallest, are only about 33; 40 Santana 1.8; high-end cars are generally more than 50; Mitsubishi car ten generations can evo reached 148, even up to the Porsche 9ff DraXster 242.5. The relatively low off-road vehicles, Land Rover newly found that only 34.43, up a relatively high power BMW X5 sport utility vehicle is only 53.4