For those that have used K&N-style drop-in panel filters (probably not many ppl here since CAIs are the cat's meow), have you experienced genuine gains in gas mileage?

 

I saw 1-2 mpg improvements around town. Got a peak of 28.8 mpg on the highway (I may have been drafting behind an SUV too) but typically saw 26.5 before I upgraded to the CAI.

 

Was this with your CAI or drop-in replacement filter? I'm asking about the ones that replace the paper panel filter.

 

Hey there.
I can say I haven't noticed any real gain [or loss] in MPGs since adding my K&N drop-in.
On the otherhand, she feels more responsive & I'd swear the ehhaust note is a tad sweeter too.

 

I didn't see any extra power that I could feel, but the engine did respond a little better, and the gas milage did go up as I said. I put a K&N on the CAI too (the Granatelli filter was really cheap looking/feeling) but didn't see any difference there (except I know it does a superior filtering job).

 

I installed the Fram AirHog I purchased a few weeks ago. I'm going to keep an eye on the gas mileage. If I don't like it, I can always go back to my stock paper panel filter. I just don't see the need to go to a CAI and custom tune at this point. There's more than enough power for use on the street, but netting 20+ mpg is just icing on the cake.

 

What's the real scoop on the drop in K&Ns and Airhog filters? Does the computer recognize the less restrictive element without a tune? I had K&Ns on my 89 and I could really feel a slight Midrange gain and fuel mileage was up about 1 mpg. Just wondered what guys are getting on the 05-08s with this setup.
Thanks

 

There was a pretty exhaustive study done on K&N vs paper filters, and the conclusion was, as I recall, that the K&N provides almost zero benefit, except being that being a less effective filter when it's over/under oiled. Personally, I think that they are a complete waste of money. Zero mileage benefit, and close to zero power benefit.

 

The simple answer: no the computer doesn't recognize a less restrictive filter.

The more complicated one: the MAF in the mustang uses a hotwire, basically a temperature-sensitive resistive fillament that's heated by the current induced by placing a voltage across it. As air flows over the hotwire, it produces a cooling effect by conductive transfer which drops the resistance of the wire, ergo less voltage is required to maintain the temperature. The faster the air flows over the wire, the more profound the effect. One wire can't measure the mass of air flowing through the entire section of the intake tube, but you know the voltage required to maintain the temperature, and you know based on the characteristics of the sensor itself, what the velocity of the incoming air is. And if you know the cross-sectional area of the intake where the hotwire is, you can figure out the mass of air is actually flowing through (simplistically speaking, if the air is moving in at X feet/min through an area of Y sq. feet, multiply the two together and you get cu. feet/min a.k.a cfm). The engineers figured all this out and mapped the intake velocity (thus flow) directly to the voltage of the MAF. They also figured out how long the fuel injectors need to be open to deliver a specific amount of fuel, and the amount of time they're open is controlled by the duty cycle of the voltage signal sent to the injector. The air/fuel tables don't actually contain any real flow numbers (whether air or fuel), they contain values for MAF voltage mapped to specific duty cycles.

The less restrictive filter obviously doesn't change the cross-section of the intake or the MAF sensor, thus it doesn't change any of the knowns of the equation, just the variable which is uh...variable anyway (by allowing the air to flow in faster). The only reason you would need to re-tune the computer for the MAF would be if you changed one of the two knowns of the equation, either the response of the hotwire (the correlation of velocity to output voltage) or the cross-sectional area of the tube. If you either change the MAF (with a non-O.E. compatible sensor) or (usually) get a bigger diameter intake tube, then you would need to re-calibrate. That clear things up?

And no, in around town driving the high-flow filter doesn't make that much of a difference in gas milage. But everyone knows that a dirty, i.e. very restrictive filter, kills gas milage. A K&N maintains an overall higher flow than a paper filter much longer and overall will save you gas in the long run. It does a much better job filtering and it's reusable. They cost $50, and a $10 cleaning kit will last up to 5 uses (being optimistic here), depending on how big the filter is. So the $60 filter and cleaning kit could potentially last you 250,000 miles (5x 50000 miles, K&N says you can go up that far without cleaning). Or, you could spend about $15 every 15000 miles, so you would spend a total of $250 over the same span. $60 versus $250...

 

I find it odd that someone that buys a Mustang GT worries about a couple mpg? If you bought a car that requires that much attention to operating costs, I'd suggest you bought the wrong car.

Pull your air filter.
Drive the GT out from under it.
Drive a Focus under it.
Install.

Better MPG for sure. Simple.

 

Like we haven't heard that one before...

You can't blame people for wanting to save money. Nickels and dimes add up.

I can't speak for the rest of these guys but I care about fuel economy mainly because I hate stopping. I take a lot of road trips in the stang and if I can stop as little as possible I can get there with less aggrivation. And with more in my wallet...probably to be spent later on mods.

 

My dealer wanted $29.99 to replace the stock filter with another OEM paper filter. I found the AirHog online for $15 and was just wondering if there was any noticable difference. I always like learning how something works. Thanks Shaun!

 

try an airhog and get money back. its a win win, if ya dont like it, sell it and make money twice.

http://forums.bradbarnett.net/showthread.php?t=74710

 

Those things are what sold me. The dealer charging me $30. Went to Autozone and they were charging me $30 for the same OEM paper filter, but Autozone also had the K&N for $40. So...$30 for every air filter change or $40 once with $10 changes there after and less frequently than the paper.

I didn't see any gains on MPG, but 90% of my driving now is city and that's only 15 miles a day.

 

RockAuto is selling the Airhog for about $13 shipped.

 

No

 

Yeah - what he said.

 

Nope sure can't. But those nickels and dimes could be dollars and tens had they bought the right car... assuming mpg is a concern. Seriously, someone buys a muscle car and then wants to talk about mpg's? Maybe the budget was a little too tight in the first place?

 

Nope. It's called getting the most out of the car. If you get a 35 mpg Focus or a 88 mpg VW BlueMotion 1, you sacrifice performance. People want performance and fuel economy.

 

Yeah but you can't have both. Peformance and fuel economy don't mix.