AIR FUEL RATIO

A Good Mixture of Air and Fuel
So that gasoline can be burned completely, gasoline must be vaporized with air that will be burned using spark plug.car use in changeable conditions, and fuel requirements fluctuate. some conditions are:

1. when the air temperature changes from high to low
2. when road conditions change from land to rise and heavy load
3. when the engine running from idle speed to acceleration

Air Fuel Ratio
 is the ratio between air masses with a mixture of fuel, if too much or too little result will not be perfect for combustion engines. at least 14.7 parts air to 1 part gasoline to burn, this is a mix of theoretical, but in a various of conditions needed changing mixture to increase engine power.

Air Fuel Ratio in Driving Conditions

•  Starting

wall at this point intake manifold and cylinder head still cold, so that the fuel injector spray stick at intake manyfold and cylinder,air fuel ratio too lean,and engine difficult to running,so that need to increase air fuel ratio to be rich mixture,so that to easy engine running.

• Warming up

the coolant temperature, evaporation of gasoline is higher, resulting in a process not a good start, as a result require a rich fuel mixture, this condition occurs when the engine running after starting

• Acceleration 

when stepped on the gas pedal, the fuel supply is reduced due to the difference in pressure, resulting in reduced fuel mixture, so that the fuel mixture richer in need.

• Constan Driving 

These conditions fuel mixture close to the theoretical ratio

• Carry Heavy Load   

 At present a richer mixture is needed to lower combustion temperature, and keep all the intakes used in the combustion

• Deceleration

because the current engine output is not needed, disconnect the fuel in the exhaust gas to cleanrest

description above is about the conditions air fuel ratio on the car ,find another article about the engine, electrical and chassis on this blog

BASIC OF GASOLINE ENGINE FOUR STROKE

Basic principle of four stroke engine :

1. Intake Stroke 
2. Compression Stroke
3. Combustion Stroke
4. Exhaust Stroke

This engine continually repeating the procedure, so the machine can work perfectly anyconditions, to be high performance, engine need a good air fuel ratio, high compresion, and good cobustion.

1. Intake Stroke On the intake or induction stroke of the piston , the piston descends from the top of the cylinder to the bottom of the cylinder,at this time position of intake valve open, and exhaust valve close, reducing the pressure inside the cylinder. A mixture of  fuel  and air  is forced by atmospheric (or greater) pressure into the cylinder through the intake port. The intake valve  then close, a
2. Compresion  Stroke With both intake and exhaust valves closed, the piston returns to the top of the cylinder compressing the fuel-air mixture. This is known as the compression stroke.
3. Power Stroke While the piston is close to Top Dead Center, the compressed air–fuel mixture is ignited, usually by a spark plug (for a gasoline or Otto cycle engine) or by the heat and pressure of compression (for a diesel cycle or compression ignition engine). The resulting massive pressure from the combustion of the compressed fuel-air mixture drives the piston back down toward bottom dead center with tremendous force. This is known as the power stroke, which is the main source of the engine’s torque and power.
4. Exhaust Stroke During the exhaust stroke, the piston once again returns to top dead center while the exhaust valve is open. This action evacuates the products of combustion from the cylinder by pushing the spent fuel-air mixture through the exhaust valve.