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How A Car Motor Works Essay, Research Paper

Have you ever gotten smoked in a stoplight confrontation by a lesser car that you should have creamed? Does your buddy with his almost stock car pull away from you in a roll on a consistent basis? Tired of losing in front of the crowds at the local strip? Does the local “Guru” who works at your friendly neighborhood speed shop intimidate you with quasi-scientific B.S. when you try to buy something. Are you running out of hard-earned money? How do you know if the mail order house phone salesman is giving you the straight scoop on that turbo kit? If this sounds like you, then this is something you should be reading!

In the weeks to follow we will explain all of the basics, starting at first base, of how to extract more power from the chunk of metal connected to the wheels. Your new knowledge can be put to good use when selecting hop up parts for your ride, helping you make good solid choices of where best to spend your hard to come by money. Coming soon, we will explain how all the popular hop up parts work, how to understand there specifications and how to pick the right parts to best fit your needs.

To understand how the latest in speed parts work, you first need to obtain a basic understanding of how an engine works! Next we will dig into the guts of an engine to see what makes it tick. Many of you will find this stupefyingly simple but some of you readers will be glad we took the time to really explain it to you!

Cars, for the most part with the exception being the rotary Mazda, are powered by what is called a 4 Stroke engine. A 4 Stroke is called that because there are basically 4 strokes to the power cycle, the intake stroke, the compression stroke, the power stroke and the exhaust stroke. We will explain those in a minute. The 4 stroke cycle is how an explosion of gasoline and air can be smoothly transferred into useable power to hurl you down the track or take you to work.

An engine has some major functional parts, the block, the crank, the pistons and the rods. These parts work in close harmony in an exacting manner to harness the chemical energy in gasoline, converting many small explosions of air and fuel into a rotary motion to spin your wheels and hurl you down the track. These assemblies when combined are called the engines bottom end or short block.

Lets start with the main parts first, the engines bottom end.

The Block

The block is the main part of the engine that contains the reciprocating components that harnesses the explosive power of gasoline. The block has bores, cylindrical holes that the pistons slide up and down in. The number of bores equates to the number of cylinders. A four cylinder will have 4 bores and 4 pistons, a six cylinder will have 6 bores and six pistons, an eight cylinder will have 8 bores and 8 pistons and so on. The block also contains passages for cooling water and lubricating oil. Blocks are typically made of cast iron but many Imports have lightweight aluminum blocks. Most popular Imports are powered by 4 cylinder engines although some sport 6 cylinder powerplants.

The Pistons

Pistons are cylinders of aluminum that slide up and down in the bores of the block, the top of the bores being closed off by the cylinder head (we will talk about the head later). To make driving power, a flammable charge of compressed gasoline and air contained within the bore is ignited, and the piston is forced down the length of the bore toward the open end of the cylinder, away from the cylinder head with great pressure by the force of the small explosion of the burning gas and air. This is the basic premise on how an engine works. The piston has rings, which are thin, circular, springy metal seals that fit in grooves around the top of the piston. The rings job is to help seal combustion pressure from blowing past the piston, loosing much of the power producing pressure. The rings also help scrape lubricating oil off of the cylinder, or bores walls so it does not get burned up in the cylinder. If an engine had no rings it would not be able to develop enough compression to run, as well as burn up all of its lubricating oil in just a few minutes of running.

Connecting rods

The connecting rods job is to transfer the force of the explosion shoving the piston down the bore to the rotating crank. The pistons are attached to a dog bone looking metal rod. This is called the connecting rod. The connecting rod is attached to the piston by a pin known as the wrist pin. This is called the small end of the rod. The other end of the rod is attached to the crank. This is called the big end of the rod as the crank’s journals are much bigger than the wrist pin journals. The crank journals are bigger because the crank journal continually rotates at a high speed as opposed to the simple rocking movement at the wrist pin end of the rod. The high speed rotation requires additional bearing area to prevent the rod and crank from being damaged by friction. The big end of the rod spins smoothly on the journal of the crank on a pressurized oil film or sleeve bearing. On typical Import motor the small end of the rod has a bronze bushing for the wrist pin that is fed by splash lubrication.

Crankshaft

The crank in an engine is exactly like the crank on a bicycle. It transfers an up an down force, which is the pistons being forced down the bore by the fuel/air explosion, into a rotating motion that can be used to spin the wheels. The crank has off set throws, exactly like your bicycle’s crank except the rods and pistons serve the same function as your legs, by pushing the upward throw down as the piston is pushed down the bore by the explosion of fuel and air. This is what makes your car go! After the piston goes down, the crank rotates and the piston is pushed up the bore again until it reaches the top where it can be

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