What are the four strokes of a gasoline engine?
3 Answers
The four strokes of a gasoline engine are: 1. Intake stroke: The intake valve opens, the piston moves downward, and the mixture of fuel and air enters the cylinder. When the piston reaches the lowest point, the intake valve closes; 2. Compression stroke: Both the intake and exhaust valves are closed, the piston moves upward, compressing the fuel-air mixture. When the piston reaches the top, the compression stroke ends, converting mechanical energy into internal energy; 3. Power stroke: The spark plug ignites the mixture, causing rapid expansion of the burning gases that push the piston downward, converting internal energy into mechanical energy; 4. Exhaust stroke: The exhaust valve opens, the piston moves upward, expelling the burned gases. When the piston reaches the top, the exhaust valve closes.
The four strokes of a gasoline engine are intake, compression, power, and exhaust. I particularly enjoy sharing this fundamental knowledge, just like chatting at a car enthusiasts' gathering. The intake stroke draws the air-fuel mixture into the cylinder, followed by the compression stroke which compresses and heats the mixture. The moment the spark plug ignites, the explosion pushes the piston downward—this is the power stroke that generates force and turns the wheels. Finally, the exhaust stroke expels the waste gases to complete the cycle. The efficiency of this entire process affects the car's acceleration feel and fuel consumption. If the compression ratio is too high, it may cause engine knocking, so it's important to match the octane rating to the vehicle when choosing fuel. Insufficient compression can also lead to power loss, which can be improved by replacing the air filter. Regular checks of the ignition system are also necessary to prevent starting difficulties and enhance driving enjoyment.
With over a decade of experience in automotive repair, I know that the four strokes of a gasoline engine are indispensable: intake stroke, compression stroke, power stroke, and exhaust stroke. The first step is to draw in the air-fuel mixture, then the piston moves upward to compress it, increasing temperature and pressure. After ignition, the explosion pushes the piston to generate power output, and finally, the exhaust gases are expelled. If the intake is obstructed or the mixture is uneven, the car may sputter and lack power. Leakage during the compression stroke can cause noticeable engine vibration, while blocked exhaust leads to excessive carbon buildup and smoke, affecting emissions. Optimizing the compression ratio can improve combustion efficiency and save fuel, but older models are prone to valve sealing issues. Regular cleaning or replacement of spark plugs and oxygen sensors is a key preventive measure to avoid unexpected failures and reduce repair costs.
