Off-Road and Racing Off-Road
An air filter element becomes an insurance policy when used in off-road applications. Competitors will sacrifice a high-tech engine for a chance to win a race - but to win, they must finish. If the engine ingests too much dirt and debris, it may die an ugly death before the vehicle can cross the finish line.
You might think this would be the perfect application for an inexpensive, throw-away paper filter. But remember, in competition a little extra horsepower can mean the difference between coming in first or finishing second. The air filter now becomes an important part of the performance package. That's why most off-road competitors choose K&N filters. The reason? K&N filters offer maximum air flow without sacrificing filtration quality - even when they become packed with dirt. The fact is, dirt buildup on the boundary layer actually enhances the filtration process because it adds to the filtering medium.
Remember, on average a K&N filter will flow 50 percent more air compared to an equivalent paper filter. That means if all other conditions remain the same, a K&N filter will flow half again as much air as a paper filter at any point during the race.
Let's consider some hard numbers. If a paper filter, brand X, flows 700 cfm of air at a measurable degree of restriction, a K&N exact replacement filter will flow 1050 cfm at that same level of restriction. Keep in mind, this is an example using average flow numbers. Exact variables differ from filter to filter.
If both filters are run in the same off-road race, lets assume each collects exactly the same amount of dirt and that by the halfway point in a 24 hour race, the efficiency of both filters has dropped 50 percent. The paper filter is now flowing 350 cfm of air and the K&N is allowing 525 cfm of air to pass through. As impressive as these figures are, our example is seriously flawed because flow bench tests have proven a K&N filter will provide closer to 100 percent of the required air flow long after the efficiency of a paper filter has dropped to 50 percent. In other words, due to its characteristics, the efficiency of a K&N replacement filter drops at a slower rate when compared to a paper element, i.e. another way of putting it: a K&N filter will last longer under the same conditions.
Using our hypothetical 24-hour off-road race to further the point, a
properly sized K&N filter will see the racer through to the end with cfm to spare. The
equivalent paper filter, on the other hand, will need to be replaced with a fresh element
to ensure the engine has an adequate supply of air to complete the course.
Question: Do you have time for these sort of changes during your races?