Both reciprocating engines and rotary engines rely on the expansion pressure generated by the combustion of air-fuel mixture to obtain the rotating force. The mechanism difference between the two engines lies in the way of using expansion pressure. In the reciprocating engine, the expansion pressure generated by the piston top surface pushes the piston downward, and the mechanical force is transferred to the connecting rod to drive the crankshaft to rotate.
For a rotary engine, the expansion pressure acts on the side face of the rotor, thus pushing one of the three faces of the triangular rotor to the center of the eccentric shaft (see PG in the figure). This motion consists of two independent forces, one is the centripetal force pointing to the center of the output shaft (see Pb in the figure) and the other is the tangential force (ft) that makes the output shaft rotate.
The inner space (or runner room) of the shell is always divided into three working rooms. During the movement of the rotor, the volumes of these three working chambers are constantly changing, and four processes of air intake, compression, combustion and exhaust are successively completed in the swing cylinder. Each process is carried out in different positions of the swing cylinder, which is obviously different from the reciprocating engine. The four processes of reciprocating engine are carried out in one cylinder.
The displacement of rotary engine is usually expressed by the unit working room volume and the number of rotors. For example, a twin-rotor engine with model 13B has a displacement of "654cc ×2".
The rotor engine uses the rotor to rotate in a triangle in an eccentric way in a special eyebrow combustion chamber. Because of its high combustion efficiency, light weight and compact appearance, it is very suitable for sports cars that need instantaneous explosive power. The RX-8 released by Mazda in 2003 further revolutionized the rotary engine (RENESIS). The twin-rotor engine with 654 cc × 2 can output 250 PS maximum horsepower at 8500 rpm and 2 16 N.m maximum torque at 5500 rpm. At the same time, it shows lower fuel consumption and exhaust emissions than the RX-7 rotary engine, and successfully developed a brand-new four-door and four-seat pure new sports car Mazda RX-8!
In 1990s, RX-7 FD3S, represented by rotary, has been standing in the car world for 10 years. This small sports car, which emphasizes violence and driving nervousness, is very popular among Japanese young people. It can be seen in Fair Running and Forward Shanka, and there has always been a loyal group of "Seven" in China, but the difference is the local Rx-. However, the rotary engine is very easy to modify and the effect is very high, so there is not much difference at all.
The 13B-REW heart of FD3S, with the support of a twin-rotor engine with a total displacement of 1.3 liter and a Hitachi twin-turbine connected with the exhaust side, has created a powerful horsepower of more than 255 horses, which many people must find incredible, but in fact, its design is very simple, with few parts and small volume, so the RX-7 is not only super powerful. The rotary engine is powered by the rotation of the rotor, so there is no valve mechanism with high-speed characteristics, and there will be a large overlap angle in the expansion stroke, which is equivalent to the dense output of a six-cylinder reciprocating engine. Due to the low-speed torque difference (short allowable explosion time) and insufficient volume of the rotary engine, 13B-REW is equipped with sequential double turbine assistance, the first one is started at 1000 rpm to increase the reactivity, and the second one is intervened at 4 100 rpm to enhance the last stage endurance.
It is estimated that the original 13B engine has more than 350 horsepower. As long as the computer is modified and the supercharging value is increased, at least 60 horsepower can be supercharged with the straight-through filter element and exhaust pipe. So this car changed two HKS mushroom heads at first, a 95 Φ exhaust pipe (front throat 75 Φ)+computer, using HKS. It is worth mentioning that the rain palace computer exchanged by Redom ROM can still change the action timing of the second turbine, thus enhancing the acceleration of the middle section, so it is actually quite effective; In addition, it also installed two Blitz pressure relief valves to deepen the responsiveness of the turbine, and replaced the original flat intercooler with a large-capacity Trust type with aluminum reinforced pipes, and moved forward to the front of the water tank, so that the important suction temperature can also be greatly reduced.
Because the structure is too simple, there is almost nothing to change about the rotary engine. Many foreign high-horsepower games are to directly change a large turbine above No.6, and then set the ultra-high supercharging value, and you can get an amazing output of about 500 horses. In fact, because rotary has no valve, this is a local hot spot. As long as there is enough fuel injection, it can bear a lot of pressure, but it will also sacrifice the torque at low speed, so it still maintains the previous sequence of twin turbines, but obtains higher vital capacity from the engine part.
The transformation of rotary engine body is mainly the processing of inlet and outlet. In the initial stage, the casting surfaces of the intake port and the manifold are polished smoothly to reduce the suction resistance, and by the way, the external interface area of the side shell is enlarged, so that the timing can be changed and the overlap angle can be increased, that is, the reciprocating engine is converted into a large-angle camshaft. The further treatment method is to enlarge the diameter of the air inlet on the inner surface of the side shell, or connect the air inlet to the rotor shell, which is a considerable modification; The final outer ring reconstruction is to seal the four air inlets originally located in the side shell, and then open a large air inlet equivalent to the exhaust port on the rotor shell, so that a large amount of air can be directly and smoothly sucked from the rotor shell, which is more efficient than the side air inlet indirectly introduced into the combustion chamber in the high-speed range. Therefore, most racing engines without turbines adopt this method.
When rotary improves its horsepower through body modification, it must lose low-speed torque in exchange for high-speed horsepower, so tuner only adopts the first mode of grinding and slightly increasing the air port, which can increase a lot of power under the setting of Hi-boost, and the estimated output should be 350 to 370 horsepower. On the other hand, after such modification, the computer must be further modified, especially the combustion chamber of the rotor will move, and the flame propagation mode must be very poor during explosion, so the ignition timing must be accurate enough. This part of the serial e-manage programmable computer rewrites the data, hoping to play the horsepower more stably.