Maximizing Engine Power

Four-Stroke Engine

The Four-Stroke Engine

When it comes to carrying out performance modifications on a car, there are generally two areas that you can focus on: the engine and the chassis, which includes the body and the suspension. The reason for this division is because engine modification will produce more power while modifications to the chassis and body will affect how the extra power gets applied to the road and translated into higher straight-line and cornering speeds.

We discuss modifications to the chassis, including suspension tuning and weight reduction in our chassis and suspension section. In this section we will focus more on engine modifications where the basic aim is to increase the amount of air that we can get into the combustion chamber. However, before we can start talking about engine tuning and increasing engine power and torque, we first need to have a basic understanding of how an internal combustion engine produces power. Therefore, over the next few pages of this section, we'll discuss the various basic concepts and principles of the internal combustion engines and the common terms used to discuss engine modifications, such as volumetric efficiency, engine displacement and air density as all of these influence engine power and performance. We also have a glossary of car modification terms that you can check for the meaning of some of the terms we use on this site. Once we have a clear understanding of how a four-stroke engine produces power, we can move on and start make our P.L.A.N.s to increase engine performance.

Although there are two types of internal combustion engines, namely the two-stroke engine and the four-stroke engine, we're only interested in car performance and since the two-stroke engine is not used on cars, we won't be discussing that engine here. Instead we'll focus out attentions solely on the four-stroke engine because is all about car tuning and because cars use the four-stroke engine and not the two-stroke engine. If you're looking for information about the two-stroke engine, you could try How Stuff Works or Wikipedia.

The rotary engine

The Wankel Rotary Engine

There are also numerous derivatives of the four-stroke engine – diesel engines, petrol engines, four cylinder engines, straight sixes, boxer engines, rotary or wankel engines, turbocharged engines, supercharged engines, etc. With the marked exception of the rotary engine, all four-stroke engines have a common basic design – they all consist of individual cylinders with pistons that are connected to a flywheel by a crankshaft, and they all make use of what is known as the Otto Cycle. This makes it fairly easy to discuss basic engine power concepts as we don't need to concern ourselves with V's and straights, boxers and horizontally opposed engines. Instead our discussion can and will be all about the four-stroke internal combustion engine. In addition, the diesel engine has had a resurgence in recent years and has become more of a performance engine, especially the turbo-diesel engine. A lot of what we discuss here can be applied to modern diesel engines but there are some aspects of engine modification that are specific to diesel engines; for this reason we'll discuss diesel engines and diesel engine modifications on their own.

So let us begin by looking at the four strokes of the four-stroke internal combustion engine otherwise known as the Otto cycle. You can skip this section if you're already familiar with the Otto cycle and head on over to basic engine power or engine building, but this section does tie into most of what we discuss on If you're interested in modifying diesel engines, hop on over to our section on diesel engines to find out how to apply our discussions to diesel engines.