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K & n high flow air intake

8K views 35 replies 15 participants last post by  Part Deux 
#1 ·
Just installed the K&N HIGH FLOW AIR INTAKE took a 2300 mile trip found no more power, did not sound better or even different so would not recommend spending the $250 for this upgrade.
 
#4 ·
Unfortunately more air in the system with no more ability to combust the fuel more efficiently will net you a lighter wallet only. The engine has a volumetric limit and more air won't help. Combusting the fuel more efficiently in the cylinders however WILL give you more power.

If you want more power and really make a difference get some ACES IV and put it in your fuel. You will get more power, torque, and throttle response because it will help utilize more of the potential energy in the fuel as work and less as wasted heat!

http://www.chargerforums.com/forums/showthread.php?t=240618

Regards,
Brian
BND Automotive LLC:driving:
440-821-9040
www.bndautomotive.com
 
#10 ·
Unfortunately more air in the system with no more ability to combust the fuel more efficiently will net you a lighter wallet only. The engine has a volumetric limit and more air won't help.
you fail to address the restriction part in your comments. less restrictive systems WILL be a performance benefit without to need for any fancy fuel additives.
 
#5 ·
Appreciate the post was considering cold air intake. I had great luck with just the K & N air filters on a 2004 Durango and 2006 Grand Prix. Namely the GP was supercharged and paper filter clogged every 6K miles, so in the long run it saved money.

Any experiece with K & N air filter in Hemi?
 
#6 ·
Based on oil analysis, K&N tend to let in too much silicon and sodium from the road.

We always recommend the green filter as it is denim materials and while the flow is really good, it catches so much more! :beerchug:

www.greenfilterusa.com

Regards,
Brian
BND Automotive LLC:driving:
440-821-9040
www.bndautomotive.com
 
#7 ·
I feel you on this but if you want to add mods on your car it's sort of a basic must have.
 
#16 ·
I hear what you are saying and used to agree, but not so much anymore after reading independent evidence. Now, I believe the most basic and important upgrade is the Catch Can. The amount of oil picked up by mine is proof to me.:beerchug:
 
#8 ·
K&N has been dyno proven to decrease HP.
 
#9 ·
I was looking at the K&N intake when I couldn't find many listed first the 2014s. This is my 2nd Charger, put AFE2s on both, and happy with the choice.
 
#13 ·
I did K&N and tune at the same time. I don't have any issues but I regret putting the K&N on only because of how it gets bashed here.
 
#14 ·
Years ago I swapped in a K&N air filter on my Cummins powered Ram, I had been doing oil sampling since it was brand new. The first oil change after the swap and the 3 following showed a 3x increase in silicon (basically dirt). I went back to a paper element and the next oil change was back to pre K&N levels. I only lost .4psi of boost and since I'm running near 30psi already that .4 is negligible. Since I'll be running that truck till it falls apart I'll take the less dirt in engine route. Just my .02 cents
 
#15 · (Edited)
That is EXACTLY what we have been seeing with the K&N with people that run in dusty and dirty areas! Way too much silicon and sodium in the oil....especially in Arizona and places where they use salt on the road for winter use. Recommend a green filter from www.greenfilterusa.com Not affiliated in any way but really have seen a difference with that filter based on analysis.:beerchug:

Regards,
Brian
BND Automotive LLC:driving:
440-821-9040
www.bndautomotive.com


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#18 ·
That is EXACTLY what we have been seeing with the K&N with people that run in dusty and dirty areas! Way too much silicon and sodium in the oil...

Something has been bothering me all day....

I get what has been said about the K&N filter element being trash and I usually take what Brian says and run with it. So I notice that the green filters offer replacements for after market intakes already installed. Lets say I got one and put it on my K&N intake. Now it will keep the silicone and sodium out and everything stays clean.

Now will that also fix the performance issue that every has with K&N? Or is it the intake design of K&N thats the problem? They all pull air from the same place in the engine bay but it looks like the intake diameter is different.
 
#19 · (Edited)
The Green Filter will deal with the silicon dioxide and the sodium much much better while flowing the same or more than the K&N. It is the gauze design of the K&N that lets too much contaminants in.

However, without directed air....a venturi effect....the air becomes lazy and doesn't flow in fast like it should regardless of what filter is on the end of the CAI.

A good way to understand it is this.......if your engine needs 650 cubic feet per minute lets stay.......and you put on a "Performance" filter and CAI etc and you get 750 or 850 cubic feet per minute capability.....so what, the engine can only use 650 because it needs only 650. Inhaling all the air your lungs can possibly hold while then holding your breath and someone sais hey, you can breath in more air....doesn't matter, you can't!

Same reason that putting on a 90 mm or 100 mm or 120 mm throttle body on a stock car will not change anything but a lighter wallet. Same reason that you don't have 10" exhaust pipes.....less scavenge and lazy air.

Hopefully that addresses the statement more fully.:beerchug:

Regards,
Brian
BND Automotive LLC :driving:
440-821-9040
www.bndautomotive.com
 
#20 ·
A good way to understand it is this.......if your engine needs 650 cubic feet per second lets stay.......and you put on a "Performance" filter and CAI etc and you get 750 or 850 cubic feet per minute.....so what, the engine needs 650.
Yeah I understand that and mine is tuned to take that into account. Thats why it asks if you have CAI. I assume it will put more fuel in so I actually get more power.

I guess what im trying to wrap my head around is why do people say, for example, the stock air box is better than the K&N cold air intake (I've read that here somewhere) but everybody recommends LMI. Is it because:

However, without directed air....a venturi effect....the air becomes lazy and doesn't flow in fast like it should regardless of what filter is on the end of the CAI.
Basically the power increase via cold air is due to the turbulence created by the tube itself. So hypothetically you could put a K&N element on a LMI tube and the power increase would be the same as a LMI intake on LMI tube?Again, that assumes you have increased fuel since air itself wont do anything.

Im sorry if that makes zero sense, my thoughts are a mystery to me from time to time. I guess in a nutshell what makes one CAI superior to another.
 
#23 · (Edited)
Yeah I understand that and mine is tuned to take that into account. Thats why it asks if you have CAI. I assume it will put more fuel in so I actually get more power.

I guess what im trying to wrap my head around is why do people say, for example, the stock air box is better than the K&N cold air intake (I've read that here somewhere) but everybody recommends LMI. Is it because:



Basically the power increase via cold air is due to the turbulence created by the tube itself. So hypothetically you could put a K&N element on a LMI tube and the power increase would be the same as a LMI intake on LMI tube?Again, that assumes you have increased fuel since air itself wont do anything.

Im sorry if that makes zero sense, my thoughts are a mystery to me from time to time. I guess in a nutshell what makes one CAI superior to another.
I get what you are saying here. The thing that many people miss in this whole equation is that the volumetric limit of an engine is not changed with more air and more fuel. This would suppose that there would be an ever increasing amount of power with ever increasing amounts of fuel and air....yet this is not in fact realized in practical use in an Otto Cycle engine like the Hemi, 3.5, 3.6, 5.7 or 6.4.

Where performance gains are realized is getting an engine to run as efficiently as possible. Tuners will richen up the fuel mixture and advance the timing some gaining a small amount of increased horsepower. But as stated earlier, there is a volumetric limit threshold that won't be changed with traditional gasoline and NA intakes. The law of diminishing returns is in play here.

The only reason we get more power and torque using ACES IV when introduced in gasolines is because it has within itself a detergency component that gets clean and keeps clean the combustion chamber that gain deposits over time. More efficient burn and better breathing.

Then ACES IV changes the volumetric limit by adding hydrogen to the mixture that speeds up the flame front.....acting like a chemical turbo charger having the gasses expand much faster. Remember that a oxygen/hydrocarbon reaction is 25 to 75 FPS (Feet Per Second) where as a hydrogen/hydrocarbon reaction is 5000 FPS! This does change volumetrics and with the increased air will produce more power.......like we have seen over and over again on dyno results with ACES IV and a faster flame front lower octane fuel that it is mixed into.

So a CAI by itself really doesn't introduce "cold air" like it is named for. According to Chrysler, CATIA software found that bringing in the colder air from the lower front facia area in the stock box was worth 8 hp. Not my research or results but what they claimed with CATIA. Bringing in non directional (lazy) air from under the hood hasn't seen the kind of gains that many claim. More want than receipt of HP. ;)

Regards,
Brian
BND Automotive LLC:driving:
440-821-9040
www.bndautomotive.com
 
#24 ·
Basically the power increase via cold air is due to the turbulence created by the tube itself. So hypothetically you could put a K&N element on a LMI tube and the power increase would be the same as a LMI intake on LMI tube?Again, that assumes you have increased fuel since air itself wont do anything.

Im sorry if that makes zero sense, my thoughts are a mystery to me from time to time. I guess in a nutshell what makes one CAI superior to another.
The simple answer is that essentially all of the performance of a CAI comes from the tube geometry. So the answer to your first question is 'yes', the LMI will perform just as well with the K&N filter. It's all in the tube as long as the filter isn't restrictive.

The tube geometry must effectively reduce turbulence to obtain the maximum "effective diameter" for the air flow. What that means is that the tube must be smooth and of the correct diameter such that wall turbulence is minimized and that the boundary layer at the wall face is as thin as possible. This is also true of any bends in the tube (like PD stated) so that the change in air flow direction doesn't cause an eddy to form on the inside part of the bend that reduces the effective diameter of the air flow.

The biggest challenge is that the intake isn't a static flow system, it's dynamic flow. In other words, it doesn't flow at a constant rate. This means that when throttle position changes, flow increases and decreases rapidly causing the air pressure to change dramatically. This can lead to significant turbulence at the boundary layer and along the tube bends as the varying pressure waves plow into each other and pile up. (also why long tube headers perform better at high RPM than short tube headers). This dynamic flow dramatically changes the design requirements of the tube to be able to accommodate the pressure waves and maintain a consistent effective flow diameter.

The short answer is that K&N created an improperly designed air tube and got it wrong. This improper design negatively impacts power produced by the engine when compared the stock design.
 
#29 · (Edited)
So in short, a CAI with a tube of this length:



is better than one of this length?



Weird...always though longer tubes were worse since the engine had to 'suck' in more through the longer tube lol.
Not quite. You are confusing a number of things that aren't related in the way you are suggesting.

The tube isn't like a drinking straw where you are trying to "lift" a mass of fluid. With a straw, the higher you have to lift the fluid, the more resistance there is due to head pressure (weight of the liquid wanting to flow back down).

With a CAI, there is no increased resistance to flow with length (air doesn't weigh much and you aren't trying to lift it) so tube length has virtually no impact on flow. What does have an impact is clearly shown in your pics where the Mopar tube has a severe bend that causes turbulence and reduces the effective diameter of the tube and impedes flow. The aFe tube has less severe bends and therefore maintains a larger effective diameter for air flow.

For a CAI, tube length isn't as important as having the correct geometry (long tube header work differently but for a similar reason). The advantage of a longer tube is that it gives the pressure waves more space to equalize and flow to become laminar rather than turbulent. Think of a waterfall (turbulent) that becomes flat flowing river (laminar).

This is why long tube headers work better at higher rpm. The "waterfall" becomes higher and more turbulent such that more distance is required for it to settle down and become the steady flowing river flowing out of the system (laminar). This is also why we have engines with variable length intake runners that change based on engine rpm. In the future, we may also have variable exhaust tubes so that the tube length of the exhaust manifold changes with rpm just like the intake runners.
 
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#31 · (Edited)
Not quite. You are confusing a number of things that aren't related in the way you are suggesting.

The tube isn't like a drinking straw where you are trying to "lift" a mass of fluid. With a straw, the higher you have to lift the fluid, the more resistance there is due to head pressure (weight of the liquid wanting to flow back down).

With a CAI, there is no increased resistance to flow with length (air doesn't weigh much and you aren't trying to lift it) so tube length has virtually no impact on flow. What does have an impact is clearly shown in your pics where the Mopar tube has a severe bend that causes turbulence and reduces the effective diameter of the tube and impedes flow. The aFe tube has less severe bends and therefore maintains a larger effective diameter for air flow.

For a CAI, tube length isn't as important as having the correct geometry (long tube header work differently but for a similar reason). The advantage of a longer tube is that it gives the pressure waves more space to equalize and flow to become laminar rather than turbulent. Think of a waterfall (turbulent) that becomes flat flowing river (laminar).

This is why long tube headers work better at higher rpm. The "waterfall" becomes higher and more turbulent such that more distance is required for it to settle down and become the steady flowing river flowing out of the system (laminar). This is also why we have engines with variable length intake runners that change based on engine rpm. In the future, we may also have variable exhaust tubes so that the tube length of the exhaust manifold changes with rpm just like the intake runners.
one word...... diameter. the diameter and shape plays a HUGE roll in effectiveness. i agree with you that length is not a major factor, at least not when dealing with air flow. a fender mount intake with a 3.5" tube diameter will not perform as well as a 4" version, at least in the context of the hemi cars. again, your spot on about the above pics of the 3.6 kits. the mopar version with the 120*+ bend is like a road block. lol
 
#21 ·
Look closely at the LMI design vs the K&N. The original designer of the LMI did a great job on the 90° bend into the TB. Continuously changing radius on the LMI vs the constant radius of the K&N.
 
#22 ·
Thats what I figured. So im better off putting my stock one back in, selling the K&N and buying a LMI. :shifty:
 
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