Review on Motor Vehicles

This year my knowledge of motor vehicles has significantly increased. Some parts I didn't even know existed in vehicles that I now know about to an extent. So far this year we have learned about compression testing Engine theory we have also learned about what each tool is and how to properly use it. And that lubrication is huge in vehicles because without the lubrication of the engine there is a possibility of your engine seizing up or exploding. We have also learned that if you don't put engines back together properly due to lack of knowledge or just putting the wrong bolt somewhere that can royally screw your day. Each part of the engine has to be precise with the measurements if you're even off my a .0001 mm you could mess your engine up.

First I am gonna start off with air and fuel enter the engine through the carburetor. The job of the carburetor is to supply a mixture of air and fuel that will combust. During the intake stroke. The intake valve in between the carburetor and combustion chamber opens. This allows pressure to force the air-fuel mixture into the cylinder bore as the piston moves downward. Just after the piston moves to the bottom of its travel from the bottom dead center, the cylinder bore contains the maximum air-fuel mixture possible.

The intake valve closes and the piston goes back up the cylinder bore. This is called the compression stroke The air-fuel mixture is pressed between the piston and cylinder head. The third step in the 4 cycles is When the piston reaches the top of its travel called top dead center, it will be at its perfect point to light the fuel to get increased power to your power equipment.

A high voltage is created in the ignition coil. In the spark plugs, this high voltage is to be exerted into the combustion chamber. The heat produced by the spark ignites the gases creating rapidly exploding, superheated gases that force the piston back down the cylinder bore. This is the power stroke. When the piston reaches BDC again the exhaust valve opens. As the piston travels back up the cylinder bore, it pushes the spent combustion gases through the exhaust valve and out of the exhaust systems. As the piston returns to TDC, the exhaust valve closes and the intake valve opens and the process repeats itself. Ever time the cycle repeats itself the cycle requires two full rotations of the crankshaft, while the engine only creates power during one of the strokes.

To keep the machine running it needs the small engine flywheel. The power stroke creates momentum that pushes the flywheel keeps its momentum and the crankshaft turning during the 4 strokes. Those are the 4 basic steps to the 4 stroke cycle engine that I have learned this year so far. But there is so much more to learn like the lubrication systems such as the difference between the lubrication system for 2 stroke engines and 4 stroke engines.

To start off I am gonna talk about the 2 stroke engine components and what it is called which is called a mist lubrication system which is mainly only used for 2 stroke engines. In the 2 stroke engine, the inlet and exhaust ports are opened and closed when the piston moves. There are no poppet valves whereas a four-stroke has poppet valves. The difference in induction method occurs in two different ways first is the air-fuel mixture is pulled into the crankcase as the pistons move down. It is then moved from the crankcase to above the piston.

During compression, the mixture of air-fuel is forced into a small space as the piston is moving up. During start up the spark plugs ignite the mixture that is created by the pistons there for starting the vehicle. During the power stroke, the power created by compression creates the force that pushes the piston down and forces the crankshaft to turn moving all the rest of the components in an engine.

During exhaust, the gases that left over from the piston after reaching BDC is expelled. If you are driving a normal everyday driver around town about 50 mph you are creating roughly around 4000 controlled explosions per minute in the engine as the spark plugs ignite the air-fuel mixture to send the vehicle down the road. These controlled explosions create a huge amount of heat in the engine if not control the engine will destroy itself but that is why there is a cooling component throughout the engine.

The cooling system has changed very little over the years all the way back to the Model T. But the systems have become way more reliable and efficient. The aspect of cooling systems is still the same a liquid coolant is still released through the engine cooling everything that is heated and is circulated out towards the radiator then the liquid is cooled by the air that comes from the grill of the vehicle. The cooling system today must keep the engine at the same temperature whether the outside air temperature is 100 degrees Fahrenheit or 20 below zero. If the engine temperature is too low fuel economy will suffer and emissions will rise. If the temperature is allowed to get too hot for too long, the engine will self-destruct.