This collection of articles consists of four parts. They will help to explain the origins of Engine Tuning, explanations of the engine tuning process and how, the now popular car tuning and performance development industry works.
This article is Part 1 of 4 and gives an initial understanding of Power Torque and Volumetric efficiency.
Before we can fully understand the engine tuning process we must first look at Power Torque and Volumetric efficiency. Power is defined as the rate of doing work, and has units of Kilowatts (kW - named after James Watt) used widely in Europe or horsepower in the old Imperial units, used here in the UK and in America.
To see what power actually is, we look at the experiment that James Watt carried out in order to give a quantifiable standard for how much work could be carried out in a set amount of time. He wanted to know the rate at which work horses could raise coal from a coal mine.
To do this he measured the mass of coal brought up the mine shaft, the distance that the coal was raised, and divided this by the length of time that it took to do this. He found that the horses would lift 33000 pounds 1 foot in one minute (or 1 pound 33000 feet in one minute), this unit of power became known as the "Horsepower."
In metric terms, the Watt is defined as the power to do one Joule of work per second. One horsepower is equivalent to about 746 Watts, or 0.745699872 kW. Now, we need to understand that power and torque are closely related and that by adding time to a force will give you power. Torque is basically the rotational equivalent of a force and is really the potential to do work and power is the rate of doing work. So, with a combustion engine, power is the torque multiplied by the radial velocity (speed) which is a measurement of time.
