How K&N Validates Horsepower Gains from Intake Systems

K&N intakes typically add an average of 15-25 additional horsepower over a stock system. Because vehicle makes, models, and engine sizes vary widely, along with vehicle condition, power gains also vary across applications and individual vehicles. However, each K&N intake system undergoes a rigorous testing protocol to help ensure that the design will deliver an increase in horsepower, torque, and airflow.

K&N's horsepower/torque testing is performed on wheel-based dynamometers, which measure actual brake horsepower and torque at the wheel(s) receiving power from the drive train, and help provide a power estimate that is likely to more closely reflect real-world conditions than an engine-based dynamometer.

K&N’s standard horsepower/torque testing is designed to measure relative power differences on a vehicle with and without K&N products installed, and SAE (Society of Automotive Engineers) correction factors are utilized to help ensure accuracy. The SAE correction factor standardizes temperature to 77-degrees Farenheit, pressure to 29.23 Hg, and 0-percent humidity.The laboratory also works to maintain that other controllable factors are held constant, including testing on the same vehicle before and after intake installation.

K&N has noticed that SAE corrected horsepower values can vary from day to day even when testing the same vehicle, due to the manner in which the vehicle's on-board computer adjusts for varying climate conditions. For example, if a vehicle is tested at sea level on a sunny and warm day, the dyno will apply a SAE correction factor to adjust the conditions to a standard temperature and pressure (STP) and the vehicle's on-board computer will also apply a set of operating parameters. If that same vehicle is tested at a high altitude on a rainy and cold day, the dyno will again adjust to standard temperature and pressure, while the vehicle may adjust to a different correction factor than it did on the sea level test. In other words, it is very possible to manipulate the results of a dyno test by testing a vehicle under different temperature and pressure conditions.

Due to the high sensitivity of horsepower testing equipment, changing even one or two factors can dramatically alter the results. For this reason, K&N engineers always test products on the same vehicle on the same day. In looking at dyno charts for some intake competitors, consumers have noted that the vehicles used before and after testing are frequently different, and that competitor tests are often performed on different days—sometimes even weeks apart. While the horsepower gains on such charts might look impressive initially, it begs the question as to how accurate those results will be when applied to a real-world application.

K&N’s intake systems are tested on the dynamometer for five runs with the original stock intake system, and five runs with the K&N intake kit installed. Engineers then exclude the highest and lowest numbers from the runs with the modified system, and select the run with the best average horsepower gain from the remaining runs. While many competitors calculate horsepower gains based on averages, K&N publishes results straight from the dyno.

The ambient temperature and atmospheric pressure at the time of the run is printed on the chart, along with the correction factor, which is used by the dyno to calculate the horsepower and torque relative to standard conditions. This correction factor helps to ensure that our power gain measurements are as accurate as possible, and that the gains shown are not affected by changes in environmental conditions.

K&N’s horsepower increase estimate is representative of the gain that similar vehicles should realize. Due to the uniqueness of each vehicle, there are occasions when a vehicle will experience a much larger or much smaller power gain than other identical model vehicles. However, customers can feel confident that K&N engineers purposefully select vehicles that will be representative of real-world power gains in most similar vehicles. K&N has been trusted in the automotive industry for over 50 years, and millions of customers rely on our reputation for integrity and transparency. 

If you notice horsepower claims from other manufacturers that seem too good to be true, we encourage you to do your own research. Check the dynamometer reports for vehicles, dates tested, and whether or not correction factors are used. Whether you choose to purchase from K&N or a competitor, we hope that you are able to do so with confidence.