K&N High-Flow Air Intake System Adds Horsepower to 2008 - 2015 Harley Twin Cams

K&N RK-3947B intake for Harley-Davidson motorcycles

Most Harley riders would love a bolt-on solution that adds a little extra acceleration when passing slower traffic up a hill or going around a truck. K&N has the answer for many 2008 – 2015 Harley-Davidson FLT and FLH riders with its RK3947B high-flow air intake system, which adds over seven horsepower with a simple installation.

The Twin Cam motorcycle engines have been manufactured by Harley-Davidson since 1998. Although these engines differ from the Evolution engine, which has been evolved from the series of single camshaft, overhead valve motors that were first released in 1936, they share a number of characteristics. Both engines feature two cylinders in a traditional Harley-Davidson 45° V-twin configuration, both are air-cooled (although some touring models use liquid cooling for the cylinder heads) and activate valves via push-rods.

When Electronic Fuel Injection (EFI) first became available in 2001, it opened up a world of opportunities for upgrading and customizing the performance of the Twin Cam engine.

In order to get the most out of your EFI system, you need an air filter system that flows better than stock. The K&N RK3947B high-flow air intake system has been developed to add horsepower and acceleration to your Harley through an increase of up to 50% more air flow, which the EFI system can turn into more power.>

K&N RK-3947B intake installed on Harley-Davidson motorcycles

The K&N high-flow air intake system eliminates the stock OE air cleaner assembly and replaces it with a complete intake assembly. The sturdy, custom aluminum backing plate mounts directly to the throttle body via an aluminum integrated, internal-run breather system. Inside the intake system is an oversized K&N air filter feeding a dyno tuned velocity stack specific to the Twin Cam which directs airflow to the engine. A black powder coated aluminum cover with a subtle K&N logo finishes off the package.

And the performance benefits of the K&N RK3947B intake system isn’t just advertising copy. In fact, K&N dyno tests show an estimated 7.03 horsepower increase on an otherwise stock 2015 Harley Street Glide.

The key to improved airflow through K&N air filters is that they’re manufactured from several layers of pre-oiled cotton filter media, rather than restrictive paper often found in many replacement filters. K&N filters also provides outstanding microfiltration, removing the most damaging particles to your engine, to ensure a long engine life for your Harley. K&N conducts its own in-house ISO 5011 air filter efficiency testing, which follows International Standard Organization procedures to verify that each K&N air filter meets these standards.

The only maintenance required for a K&N Harley intake kit is a service you can do yourself in no time at all. Once a year, depending on riding conditions, with just the K&N air filter cleaning kit you can easily renew your air filter, and prepare it for another year of riding. Your one K&N air filter is designed to last for the lifetime of your bike, which K&N guarantees will perform for up to 1,000,000 miles or 10 years without requiring replacement. For full details visit the K&N Million Mile Limited Warranty.

To find additional K&N upgrades for cars, trucks, scooters, motorcycles, motorhomes, or just about anything powered by an engine, use the K&N search by vehicle tool. Find an authorized K&N dealer nearby using the K&N dealer search.

The Harley RK3947B fits the following bikes:

K&N RK-3947B intake parts included

Not legal for sale or use on any pollution controlled motor vehicle in California or states adopting California emission procedures. See knfilters.com for CARB status on each part for a specific vehicle.