What are the advantages of horizontally opposed engines?
The layout of the engine compartment is relatively complicated due to the difficulty in manufacturing technology requirements and the high manufacturing cost of the horizontally opposed engine and the shape of the cylinder block of the horizontally opposed engine. It is rarely used in current models, only Subaru and Porsche are using horizontally opposed engines. The advantages of the horizontally opposed engine: The pistons of the horizontally opposed engine are evenly distributed on both sides of the crankshaft and move about 180 degrees in the horizontal direction. The torque generated by the lateral movement of the piston cancels out bilaterally symmetrically and has a good balance. When the vehicle is running, the vertical and vertical runout (vibration) of the vehicle is greatly reduced, so that the adhesion of the vehicle is large, the grip is strong, and the vehicle runs relatively smoothly. The overall height of the engine is low and the length is shortened, so that the center of gravity of the vehicle is lower than that of the vehicle with a vertical engine and a V-type engine. At the same time, this horizontal piston layout reduces the balancing weight required in the crankshaft, which helps to increase the engine speed. In addition, the cylinder layout of the horizontally opposed engine is a symmetrical stable structure, and the power loss during operation is also minimal, which is also the reason for fuel saving. Disadvantages: Because the position of the exhaust pipe must be directly below, and both rows of cylinders have exhaust pipes, and there is a crankcase in the middle, it is difficult to lay out the exhaust pipes. In addition, the large lateral size of the engine makes the cabin space compact, which also causes trouble for the forward rotation mechanism. In addition, the opposed engine will affect the layout of the double overhead camshaft / four-valve. If it is to be achieved, it must have a longer timing belt or timing chain drive, so it is too complicated compared with the inline engine. In addition, due to the particularity of the horizontally opposed engine, in the lubrication system, the oil will sink under the influence of gravity. For example, above the contact surface of the piston and the cylinder wall, the lubrication will be slightly insufficient, and the oil below will be excessive. Working in a high-temperature environment, the engine seals face greater challenges in the face of oil leakage.