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Cold air intake or just K&N for better fuel economy?


rltrbill

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I know this is a pretty old thread but I wanted to get on here and find out if anyone was using a cold air intake. I just wanted to reply to the notion that more air into the engine means more fuel used. That notion is pretty ridiculous. Any time you make an internal combustion engine "breathe" easier, you increase it's efficiency. A fuel injected car will operate at a set fuel mixture point. That is true. It is the downstroke of the piston in the engine that draws air into the motor. When you make it easier for the engine to do that, (with a higher flowing filter) you reduce the amount of energy wasted on drawing that air in. That is why a turbo or supercharger increase power while adding efficiency. They remove that drag on an engine. The same holds true for exhaust. The freer flowing the exhaust, the less waste of energy pushing the spent fumes out. I just wanted to find out if anyone replaced the air intake tube from the filter box to the throttle body.

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I know this is a pretty old thread but I wanted to get on here and find out if anyone was using a cold air intake. I just wanted to reply to the notion that more air into the engine means more fuel used. That notion is pretty ridiculous. Any time you make an internal combustion engine "breathe" easier, you increase it's efficiency. A fuel injected car will operate at a set fuel mixture point. That is true. It is the downstroke of the piston in the engine that draws air into the motor. When you make it easier for the engine to do that, (with a higher flowing filter) you reduce the amount of energy wasted on drawing that air in. That is why a turbo or supercharger increase power while adding efficiency. They remove that drag on an engine. The same holds true for exhaust. The freer flowing the exhaust, the less waste of energy pushing the spent fumes out. I just wanted to find out if anyone replaced the air intake tube from the filter box to the throttle body.

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More air into the engine always requires more fuel - no way around that.

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"Breathing easier" is also a myth. The only thing that matters is the volume of air and the density (oxygen content). A freer flowing intake, filter and exhaust simply allows MORE air to enter and exit the engine. An engine is nothing more than an air pump - the more air you can get in and out the more power you can make.

Ā 

There is no "drag" on the engine based on the intake or exhaust. It's strictly the oxygen content of the air that gets pulled in when the valves open.

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Akirby is a direct vendor for AEM and K&N air filters. For more information just PM him and he will help you out. ROFLMAO

Ā 

More air into the engine always requires more fuel - no way around that.

Ā 

"Breathing easier" is also a myth. The only thing that matters is the volume of air and the density (oxygen content). A freer flowing intake, filter and exhaust simply allows MORE air to enter and exit the engine. An engine is nothing more than an air pump - the more air you can get in and out the more power you can make.

Ā 

There is no "drag" on the engine based on the intake or exhaust. It's strictly the oxygen content of the air that gets pulled in when the valves open.

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I agree that an engine is just an air pump. All I was stating is that a less restrictive system allows that pump to operate more efficiently. My point is just that reducing the amount of negative pressure created by the engine when drawing in air takes some of the load off the engine. An engine will always use a certain amount of air and fuel to achieve a certain RPM, the harder an engine has to work to reach that RPM determines the amount of air and fuel needed. I've used K&N filters in my explorer and my Hemi Ram. I did notice improved throttle response and slight gains in mileage. I drive 60 miles a day, back and forth to school. Even the slightest gain would be to my advantage. I do also consider my driving habits. I get about 20 mpg which isn't bad but I'm always looking for that little extra. Thanks for the info though. I'll keep that in mind.

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You're overstating how hard the engine has to "work" to pull in air. When you remove intake or exhaust restrictions you simply allow more air into the engine and that's where the extra power comes from. Not from reduced load. And that difference only shows up at WOT or close to it.

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You can put a cloth diaper in the airbox and still get better mpg - somebody actually did that test.

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But I'm not going to continue to argue about it. Believe whatever you want to believe.

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As for the K&N providing better fuel economy, if that were true then K&N would have hard data posted all over their website to support it just like they have dyno runs showing hp gains. They don't. Draw your own conclusions.

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  • 3 months later...

I have a 2010 and cut the air box off and put a k&n cone filter in its place. They make one with the exact ID needed to fit snugly around the factory tube. I think it's 3.25 inches, I don't remember, it's been awhile. I used a hose clamp to secure it on and zip tied it to the batt cable. I at some point will be making a heat shield from some sheet metal to block the engine heat and make some caps for the air silencer thing. I can't say I noticed any difference and really wasn't paying attention because I know it improved air flow and that's all I was going after. I also recently got a sprint booster for the throttle response delay and having felt the difference that makes, I will not be returning it. It does nothing for performance but still a must have for the way I drive. Haven't messed with the exhaust yet but will be very soon.

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Make sure to use some insulation on the heat shield, preferably on both sides, but definitely on the inside (towards the filter). The heat shield should ideally seal to the hood when the hood is closed, so you can experiment with weatherstripping for that.

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How about videos/pics of your setup as it progresses? Would be cool!

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My input and I used K&N filters for 10 years. I switched to the AEM dry filter to get away from the oil and cleaning routine. Can not say there was any noticeable difference between either brand. The benefit however is I do not have to buy a recharge kit for the AEM and thus the AEM becomes even cheaper to use and own. I also do not like cleaning them so I purchased the Filter Minder and installed it on my air box to let me know when I ACTUALLY need to clean the AEM air filter. Installed the filter minder in December 2015 and have since put about 20,000 miles on the AEM filter and the filter minder is still in the green. I am monitoring it for when it will actually need clean when it pops to the yellow or red. To your point no noticeable fuel savings and no noticeable power increase. Purely a way for me to reduce maintenance time. IMO

Yeah akirby. Give some criticism. I'm all for it. And please if anybody would like to give me advice or their opinion I'd like to know it. Thanks

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So what's with the idiom? Are you saying my efforts to improve airflow are pointless as it will have no effect on performance? Because I have a hard time believing it doesnt. I didn't say it improved performance because I have no evidence to prove it but it should be obvious it did. And when I say performance I'm referring to HP gain and nothing to do with mpg. Thanks for replying!

Edited by wilso00000
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And I will look into an aem air filter. When I got the k&n I didn't bother researching other brands, mainly because I assumed they were the best and I already had the cleaner stuff. The airbox had to go tho, surely you have seen the size of the opening for air to come in. It's small, and while it may be cooler air than my current set up, it won't be when I'm done. And I most definitely will be putting some insulation on the inside of the heat shield as well as some weather stripping for against the hood. My next step tho is to get rid of the center muffler and I will be sure and use my little db meter to log the difference as well as some video footage. I know, there's another thread for that

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That by reducing the air restriction would increase air flow to allow whatever air the engine wants to get to it? I've tried to do some research into this and haven't come up with anything that would lead me to believe that leaving the air box intact is better than removing it and putting a cone filter in its place from purely an air flow point of view. Is there some magic to forcing the engine to suck air in instead of readily supplying it with as much air as it could want? Enlighten me a little, that's why there are forums, right? At least I'm not saying that my mpg increased due to the weight removed from the airbox which it did by .008 mpg actually. Yeah that was a joke. Seriously, am I missing something here? I do realize that the air flow might have been optimal before my airbox extraction, which one would think was the case, but I don't think it is. Why else would anybody claim to increase HP by changing it up with a cold air intake which incidentally removes the airbox? Unless other factors are involved that they fail to discuss?

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Ok - let's get the mpg thing out of the way since that's the biggest source of debate around here. You are correct that the air filter doesn't affect fuel economy one way or the other - less restrictive or more restrictive - on a modern fuel injected closed loop engine. The engine controls monitor and adjust the fuel to match the airflow and maintain the proper A/F ratio. More air - more fuel. Less air - less fuel. Actually I should say oxygen, not air. Denser/colder air adds more oxygen and requires more fuel.

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A higher flowing filter will absolutely add more power - but usually only a few hp (maybe 10-15 under ideal conditions) and then it's only at WOT. You'll get the same power below WOT with a paper filter just by opening the throttle a bit more.

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That's the science.

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