The engine component responsible for providing air for combustion. A typical air intake comprises an air box, which contains the air filter, and an intake tube, which delivers the clean air to your combustion chamber.
In an air intake system, the intake tube connects the factory air box or performance filter to the mouth of the throttle body. Intake tube designs can vary greatly. Stock models typically feature a number of bends and a smaller tube size. These design characteristics of stock intake tubes help the intake system fit in the engine compartment and reduce intake noise. Performance intake tubes look drastically different. The tube diameter is usually much larger than a stock part, and bends/turns in the tube's shape are minimized to improve airflow. Materials and particular design characteristics vary by model, as manufacturers do what they can to maximize performance.
The ratio of air to fuel used during the combustion cycle of your engine. Mixtures heavy on fuel are called “rich,” mixtures light in fuel are “lean.” Engines come with a pre-set programming of air to fuel ratios, known as a fuel map. Your engine senses the amount of air entering the combustion chamber and responds with the corresponding amount of fuel based on the correct ratio.
This type of bending is the least restrictive and will give you the most performance because the pipe's diameter remains the same throughout the bent areas. To keep a pipe's size uniform, a flexible rod called a mandrel is inserted inside the pipe before it is bent. With the mandrel inside, the pipe can be bent without crushing in on itself. This is critical, as a crushed pipe will diminish airflow.
These pre-established points are married to a specific RPM threshold at which your automatic transmission throws to the next gear. Performance modules and programmers most often change these shift points to get you into high gear faster than factory settings, which are both more powerful and more efficient than lower gears.