Introduction: Here at Treadstone one of our main goals is to educate our customers to provide them with the knowledge to safely boost any vehicle they desire. This is why we have decided to introduce “the basics,” which will be a series of blogs that will present information in a simple to understand format with liberal use of lamens terms. Today we will cover the topic of MAF Pipes, how they function, their importance and the different variation. First a few definitions, MAF stands for Mass Air Flow, typically this was the only way modern engines monitor the air entering your engines. Today’s modern engine use an array of different sensors to closely monitors air going into the engine but the MAF sensor remains an important part of the performance equation. How They Work? There are two of the most common types of mass airflow sensors, the vane meter and the hot wire. Neither of these sensor designs measure air mass directly, but in conjunction with other additional sensors and inputs, the ECU can determine the mass flowrate of intake air. Both of these sensors output a 0.0–5.0 volt signal that is proportional to the air mass flow rate, and both sensors have an intake air temperature sensor incorporated into their housings. This allows the computer to access its array of equations to determine the actual rate of flow entering your engine. Their Importance! So what does all of this mean? All of this equates to a simple setup, since the factory ECU was embedded with predetermined set of equation and parameters, when those parameters are changed without a recalibration to the ECU the end result is an undesired one. i.e.: if the factory air intake was setup for a 2.5” inside diameter pipe and a customer replaces it with a larger 3.0” diameter pipe. The incoming air velocity slows down due to the larger area in the tube, the MAF will then send a lower voltage and read less air going into the engine then there actually is, and the end result would be a leaner air/fuel ratio that may cause per-ignition/detonation, melted pistons, or worse destroyed engine. Larger diameter pipe will cause the engine to run lean without recalibration of the ECU! On naturally aspirated engine, some manufactures will increase the size slightly on cold air intakes, without retuning, because a N/A car makes more power when it runs leaner. But, care must be taking on forced induction engines, because running leaner can have a much more catastrophic effect! Conclusion When changing or upgrading a component on a modern internal combustion engine the proper step must be made to insure the change is done safely. The most important rule to remember is, tuning is king!