1. Our '09 F-150 has Ford's...
1. Our '09 F-150 has Ford's three-valve 5.4-liter V-8, factory rated at 310 horsepower and 365 pound-feet of torque. Much of the engine compartment is filled with the air box (bottom) and the resonator chambers on the intake tube, both of which get streamlined with the K&N Intake Kit.
If we've learned anything from recent history, it's that there aren't a lot of people interested in buying new pickups or full-size SUVs. Although that's bad news for Ford, Chevy, Toyota, and others, companies that make products to improve efficiency and fuel economy are doing quite well.
There are plenty of simple ways to improve the fuel economy of your truck, but some of the easiest have to do with improving efficiency. In fact, one of the simplest ways to improve any big V-8 is to make it a better breather. Substantial gains can be made by swapping out the (in most cases) restrictive factory air intake setup, with its multiple resonator-chambered tubing and low-flow paper filter, and substitute a higher air flow, reuseable air filter, like those offered by K&N, AEM, aFe, Bully Dog, and others. We like the idea of saving money on air filters as well as the promise of more power so we decided to take a closer look. For this scientific endeavor we enlisted our 2009 Motor Trend Truck of the Year long-termer Ford F-150 and asked the tech guys at K&N to give us exact before-and-after dyno numbers. We'd be doing some further road testing on our own.
At this point, it's worth noting that all new truck manufacturers do a pretty good job tuning their engines with equal emphasis on power and quietness. However, with so much attention to reduced interior cabin noise by new vehicle buyers, powertrain engineers work long and hard at getting as much noise reduction from the engine as possible. The results on the intake side of the engine have resulted in numerous, bulb-like chambers typically branch off the main intake runner from the filter box, designed specifically to isolate and cancel various sounds generated by the rushing and sucking air as it channels through the filter and toward the combustion chamber.
2. The factory paper filter...
2. The factory paper filter is as large as a college textbook. Air is sucked from the driver-side fenderwell, through the paper filter, and then drawn into the throttle body. Our filter (changed just 2000 miles ago) is quite dirty, making it difficult for our pickup to get big gulps of air when needed. We would have shelled out about $15 at the local autoparts store for a new one pretty quick.
We found, once the K&N High-Flow Intake kit was installed, the engine noise levels were slightly louder and more pronounced during hard and moderate accelerations; however, idle and cruising speeds showed no noticeable changes. As a side note, our guess is that many enthusiasts may like the more throaty and raspy noise the engine makes when pushed a bit, as it gives the impression there may be more under the hood that one might suspect. We didn't find the throatier sound unpleasant at all, and appreciated the tone difference when we pulled up alongside another '09 F-150.
Additionally, we found a slightly quicker throttle response after installing the kit; we assume a direct result of the reduced restriction and smoothed air running from filter to combustion chamber.