Gas Mileage Improvement

by Steve on June 23, 2006

Subtitle: Why isn’t this simple upgrade standard equipment?

Driving a big SUV is decidedly not PC nor is it “green” or easy on the wallet. But when your life requires hauling and towing capacities greater than the size and weight of most hybrid vehicles, you don’t have many options. The old neighborhood adage, “Everyone is your friend when you own a truck” has never been more true. After all, why own one when you can borrow one? Well, you borrow it and it damn well better come home with at least as much fuel as it left with. These days bringing it home empty is more than just bad manners, it’s $75.

But I digress, back to my point. The standard engine for the entire line of GM trucks for the last six years has been the 5.3 liter V-8. GM engineers have fiddled and tweaked that motor to the point where the ’06 trucks get about 19-20 mpg on the highway. My 2001 Yukon XL only yielded 16 mpg highway until a few weeks ago. I installed an Air Raid high flow air filter system. The first two tanks after the install didn’t indicate any noticeable improvement and I sadly thought I had wasted $200. What I didn’t realize is that it takes a while for the computer to adjust various parameters to compensate for the increased airflow. On the third tank I was convinced I was looking at a sticking gas gauge sending unit: it was still showing over half a tank remaining while the trip odometer was at 250 miles plus. I always back up the fuel gauge by resetting the trip odometer when I fill up. Old aviator thing I guess, wanting redundant indications of fuel remaining. Normally I’m showing about an eighth of a tank remaining when the odometer reads about 350 miles. So I dropped the fuel gauge out of my scan – must be unreliable – and watched the miles per tank. I filled up at about 350 miles but it didn’t take as much fuel as usual. The gauge was correct. The ECU had recalibrated for the airflow and my highway mileage had increased to 19 mpg.

An increase of 3 mpg for an investment of $200, figure an average of $3/gal, resultant savings of $.03/mile and the payback is about 6666 miles. The Air Raid system simply replaces the restrictive plastic OEM filter box and disposable paper filter with a much more open filter shield and a reusable K&N type fabric filter. Some assembly required and you must periodically remove the filter, clean it, and re-install it but if you can work a screwdriver and socket ratchet you can install and maintain this filter. The only down side to this modification is a higher noise level in the cabin when you really put your foot in it. That wide open air box doesn’t muffle the noise as well coming back out of the intake at full throttle, gives it a deeper growl out of the hole. It’s not nearly as noticeable as the “sport exhaust” that Dodge is selling on some of their trucks, the factory version of the popular NASCAR mod: dual exhaust with high flow (reads “loud”) non-mufflers. The trucks that beg the question: “Why?” I can accept a little muffled growling from under the hood for a 19% gain in fuel efficiency.

Politicians keep calling for higher mpg ratings to be imposed on Detroit and Motown keeps countering with complaints about technical limitations and various other reasons why they can’t make it happen. I’d have to say that’s a load of BS: I just improved my highway mileage by 19% by swapping out the filter system. No changes that adversely affect emissions. Simply let the beast breathe better. The next test will involve an aftermarket throttle body spacer that is supposed to further improve airflow and increase mileage.

Hello, Detroit. Anybody listening? If I can improve gas mileage using commercially available parts why are you not incorporating such simple improvements into your designs? Get with the program.

Disclaimer: Your mileage may vary depending on vehicle type, condition of engine, driving habits, tire pressure, hair color, and any prescription meds you are currently taking (among other things – the possibilities are endless).

Second disclaimer: This is not a paid endorsement and the author’s results were unscientifically obtained during actual highway driving. No warranties or guarantees are implied or stated. Product contains materials known to be fatal to Norwegian lab rats domiciled in the state of California at elevations greater than five thousand feet and forced to survive on consumption of said material at a rate of ten times their body weight per day.


Curtis July 20, 2006 at 5:39

I did the pretty much the same thing with my 02 Sonoma. I paid 275 to install a K@N cold air intake system. Not only did I gain an additional three to four miles per gallon, but my torque and low end acceleration noticeably improved. The engine picked up a bit of a deep steady growl, (That I personally like) but other then that there were no adverse effects whatsoever.

Seriously, the car companies are cheaper then your old man. One of the first things I learned when I started working on my vehicles is to never buy OEM (Factory standard/replacement) parts. Always buy a grade or two above. It will cost a little more, but the jump in quality is rediculous.

Ed December 7, 2007 at 14:05

I had tried the K&N filter setup as well. However, I then consulted with another after market vendor of automotive maintenance products who pointed out to me that there will be a trade-off by going the route of an air filter with essentially larger pore openings. An air filter’s purpose is to protect the engine from airborne particulates that can and will cause engine damage. By allowing larger openings, larger parts of trash enter the engine, leading to premature engine failure. Makes sense to me, so you have to weigh gas efficiency now followed by engine repair sooner. A moot point if you don’t keep your vehicle very long! Just my opinion…

Danny December 11, 2007 at 21:20

I had a K&N system on my 98 Chevrolet with the 5.7 and had 223K miles when I finally traded for an 07 Chevrolet truck that I have yet to add one to. As long as you keep the K&N systems oiled and cleaned they clean better than the cheap paper filters.

weber January 9, 2008 at 3:59

I have not got a k&n cai yet. but i have look in to in. ed i would not worry about the trash getting in to the motor go to their website and watch and read. mite help easy your mind.

i cant figure out which way to go. just the filter ar the hole system.

Jeremy January 23, 2008 at 16:30

I have both the cold air intake and the throttle body spacer and while it did improve my mileage it has two drawbacks. First is the spacer creates a high pitched whistling sound. Second, the obvious factor that the new filter lets more air, but also lets more trash in. Like it was said before if you’re only keeping your car for a few years, and not driving it for 10 years then it would be ok.

K Lindley March 9, 2008 at 22:16

In response to Ed’s comment posted Dec. 7, 2007, I have no scientific data, but I can tell you my own experience. I purchased a 2000 Ford F150 4×4 to use in my job as a procurement forester. I installed a K&N air filter shortley after my purchase. When I traded it off after 7 years and 280,000 miles, many of which were in extremely dusty off road conditions, the motor was still running good, with very little oil consumption. I’m no spokesman for any filter manufacturer, and I’m sure other people’s results will vary, however, I’m personally not worried about the extra airflow resulting in more trash in the engine. That is assuming the filter is properly maintained. P.S. All disclaimers listed in Steve’s comment above apply.

G Leavell June 19, 2008 at 13:01

I have a 2001 F150 Supercrew with 4.6L, 2-wheel drive.

I installed a K&N CAI on it. I keep a log of mileage and the CAI system gave me around .5 mpg improvement in the city and about 1 mpg improvement on the highway driving.

I ran it for about 10k miles before I removed it and put the truck back to stock configuration.

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