Suck Squeeze Bang Blow

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(Things your dad should have taught you)

This is all about the internal combustion engine. This is the first basic thing you need to know about engines to get a sense for what they are doing, why compression is important, why plug firing order is important, etc etc…

Now I started out learning this from my dad, when he would help us take apart and fix various types of engines on various types of vehicles. Cars, dirt bikes, three wheelers, lawn mowers…

From there, with the basics down, I chose to go into the automotive class in High School. Ya, thats where where people who weren’t going to be white collar folk later on in life went, as if they were too lazy for ‘real’ classes… True enough, a lot of guys who took it – and yes, it was basically just guys – but it shouldn’t be looked at like that. The basic troubleshooting skills and knowledge of how an engine works can save you a lot of money later in life as often the things that go wrong with engines are fairly simple fixes or part replacements. I think auto class should be mandatory for people. People these days don’t know how to do much either cause their dad didn’t show them, or they didn’t think it was a worthy sorta class in school (fyi, I took typing and sewing in school too and yes, they are definitely handy skills to have. Well.. for my job now typing paid off HUGE, that should be mandatory now).

Anyways, on with explanation and this is something you’ll likely never forget. From here you can start understanding why other components on an engine are required.

Here is the explanation I stole from this site:
Edmunds – a car site

INTAKE (SUCK) The intake stroke begins with the piston near the top of its travel. As the piston begins its descent, the exhaust valve closes fully, the intake valve opens and the volume of the combustion chamber begins to increase, creating a vacuum (thus the term SUCK for this cycle). As the piston descends, an air/fuel mixture is drawn from the fuel injectors into the cylinder through the intake manifold. The intake stroke ends with the intake valve closed just after the piston has begun its upstroke.

COMPRESSION (SQUEEZE) As the piston ascends, the air/fuel mixture is forced into the small chamber machined into the cylinder head. This compresses the mixture (SQUEEZE) until it occupies 1/8th to 1/11th of the volume that it did at the time the piston began its ascent. This compression raises the temperature of the mixture and increases its pressure, increasing the force generated during the ignition cycle.

IGNITION (BANG) The air/fuel mixture is ignited (BANG) by the spark plug just before the piston reaches the top of its stroke so that a large portion of the fuel will have burned by the time the piston begins ascending again. The heat produced by combustion increases the pressure in the cylinder, pushing the piston down with great force. This is the cycle that actually creates power in an engine.

EXHAUST (BLOW) As the piston approaches the bottom of its stroke, the exhaust valve begins opening and the pressure in the cylinder begins to force the gasses out around the valve. The ascent of the piston then forces nearly all the rest of the unburned gasses from the cylinder (BLOW). The cycle begins again as the exhaust valve closes, the intake valve opens and the piston begins descending and bringing a fresh charge of air and fuel into the combustion chamber.

Remember that this is a basic explanation of how the internal combustion engine works. Variations from this diagram include multiple valve and/or spark plug configurations for increased efficiency and domed pistons for higher compression ratios, to name just a few. But the basic process of SUCK-SQUEEZE-BANG-BLOW is the same for all four-stroke engines.

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