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You've heard the hype and the claims, but does anyone know for sure whether cold air induction kits actually offer any benefits over the stock air box?

We decided to find out with a quick test of the Moroso High Flow Air Induction system. The kit, consisting of a conical K&N filter and a molded tube, positions the filter in the fenderwell, eliminating the stock air box and panel filter. Many companies make similar so-called "fenderrwell" or "cold air" induction kits.

Cold-air vs. Ram-air
An important distinction must be made clear between the terms "cold air induction" and "ram air induction".

A cold-air kit simply implies that the air is drawn in from outside the engine compartment (i.e. the filter is not sucking up the heated air around the engine.)

A ram-air induction, on the other hand, implies that the air is being forced into the air cleaner assembly when the car is in motion. This is typically is achieved by placing a scoop or tube facing the front of the vehicle.

In a ram air system the engine benefits from a slight increase in air pressure, like a natural supercharger. A cold air system does not have this effect.

We know that ram-air systems do work. We tested such a system on a carbed 302 and got impressive gains.

The question in this article is whether or not there is any benefit from simple putting a filter in the fender.