Everything we do is in an effort to maximize this mass of air. Its job is to move air in and out of the cylinders. Why does this matter?ĭespite all its many complexities, moving parts and that a great chemical and thermal event is what generates the power we’re after – the engine is essentially just a large air pump. In the end the “fuller” cylinder will have a greater mass of oxygen molecules present. A cylinder with 500 grams of air in it is said to me 'more full' than one with 400 grams. The measure we are looking for here is air density. A 0.5 Liter cylinder will always have 0.5 liters of air in it. And, in the pure volumetric sense, that is correct. Seemingly, that would suggest that the cylinder is always full. As most of us will know from basic science, gas will expand to fill its container. Volumetric efficiency (VE) is typically defined as 'the actual amount of air being pumped by the engine as compared to its theoretical maximum.'īasically, VE is a measure of how 'full' the cylinders are. This can actually be a quite tricky subject, mostly due to confusion and differing opinions among many people. While the concept in relatively simple, there are many misconceptions amount new tuners and mistakes made when first tackling this concept. This is a critical component of most OEM and Aftermarket speed-density based fuel calculations. The basis of any good engine map starts with an accurate Volumetric Efficiency table.

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