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.
A thin, loosely-woven cotton cloth material used in cloth air filters. These filters average 5 layers of cotton gauze per filter held in a pleated shape by wire mesh. The loose weave allows superior airflow when compared to restrictive paper filters. And, the fibrous nature of gauze material allows strands to grab passing dirt particles in high volumes.
Refers to the process by which plastics (including polyurethane) are molded into the correct shape. The material is heated into a liquid form, and then pressed into the desired shape mold. Injection molding is key when making a performance air filter, as the exact shaping helps create the air-tight seal with the air box.
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.
Pleated material is folded to use more cloth in an otherwise confined space. In clothing, pleats allow extra material for free movement and looseness. Performance cloth air filters employ a pleated design for using as much dirt-trapping surface area as possible. This pleated design not only retains more dirt, but it also allows more places for air flow.
A plastic material that bonds many long molecules together with urethane, making the blend incredibly flexible. Polyurethane also boasts great durability for long life. Performance air filters rely on polyurethane for the injection-molded filter border to form a tight seal, preventing leakage.
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