Life in the Eyes of John

A blog on life, love, people, cars, and everything I can think about...

Wednesday, March 17, 2004

Suck, Squish, Bang, Blow

Horsepower. Torque. Top speed. Acceleration. Where do they come from?

The engine.

A common part of modern-day, petrol- or diesel-powered transportation is the four-stroke engine. Thanks to the four strokes, we have power turning the wheels of cars, jeeps, buses, and every other vehicle.

So first of all, some basics. In the internal combustion engine, a piston is contained in a cylinder. Think of it as a can (piston) in a tube (cylinder).

The piston is then linked to the crankshaft. The crankshaft is a vital component that transfers the power from the pistons to the wheels. While the pistons go in an up-and-down motion, the crankshaft is spun.

Sealing the top of the cylinder are the valves. Think of the valves as your nose; you breathe in air, then exhale carbon dioxide. The valves, on the other hand, make the engine "inhale" a gas-air mixture through the intake valves, and "exhale" exhaust gases produced by burning the mixture through the exhaust valves.

To put all these things in motion, we will remember only four words: suck, squish, bang, and blow.

So here it goes:

1. Suck (Intake Stroke) - The intake valves open to take into the cylinder a mixture of air and gas from the fuel system. The piston is pulled down by the crankshaft, effectively "sucking" the air-gas mix.

2. Squish (Compression Stroke) - All valves are sealed, and the crankshaft pushes the piston up, compressing the air-gas mix.

3. Bang (Power Stroke) - With the valves closed, either through a spark from the spark plug (petrol engines) or through sheer compression (diesel engines), the air-gas mix is burned. The burning converts the air-gas mix into exhaust gases. As a result of the burn, gases expand in the cylinder, which in turn pushes the piston down and turns the crankshaft.

4. Blow (Exhaust Stroke) - With the exhaust valves are opened and the crankshaft pushing the piston upward, the exhaust gases are pushed out of the cylinder, readying the system to "suck" again.

So that is how power is generated through internal combustion engines.

There will be a quiz.

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