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Cold Air Intakes - Differences

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5K views 12 replies 8 participants last post by  Haav2 
#1 ·
So im wondering if theres really a difference in air intakes i mean its a tube with a filter i could see maybe a higher quality filter but does it really matter if you get a cheapo for 100$ vs a 200$ name brand?
 
#5 ·
03 gtmustang said:
No but people have there opinions about them . I do know the metal ones make the air hot, i have the K&N and have to clean my maf senser every time i clean the fliter because it sucks the oil threw it ,
The difference in performance between plastic and metal is minimal anyways!.. And ya you should clean your MAF shortly after you clean your filter because of the oil!.. I've got two filters that I switch between about every 6 months!.. Ill pull the dirty one off and put on the clean one, then about a day or two later ill lean the MAF!.. But that's just me!.. Lol
 
#7 ·
There are many aftermarket units that are just that, "a tube with a filter", and that's why they suck--here's why:

The air flow in the intake tube is not a continuous stream, but rather a series of pulses (with negative pressure heads, near ambient pressure bodies, and positive pressure tails) whose frequency is proportional to engine speed. In a straight tube at certain of these frequencies standing waves (harmonics) will develop and impede the flow of the pulses at those sympathetic frequencies, this is how a trumpet, cornet or trombone works. However in an internal combustion engine intake these waves cause power surging and "suck-outs" in the torque curve. The good news is that the shape of the tube can be designed to both minimse the standing waves, and even enhance the flow at certain frequencies, and provide for better aspiration. Intakes on many performance engines even have small closed end chambers called Helmholtz resonators grafted to them to control/alter the intake tract's resonance.

The engineers that know this--Ford, JLT, and as much as I hate to say it K&N--design accordingly. This is why the stock intake, which is a CAI and a good one, is not just a straight piece of rubber tubing.

All of the others, those that are just straight-walled pieces of tubing, do nothing to enhance the flow dynamics--that is why they can actually rob power at certain engine speeds and loads.
 
#9 ·
Is that really true CLIFFYK or are the 2012 contendor of Mustang Whoppers?
 
#10 · (Edited)
You will need to read John Heywood's Internal Combustion Engine Fundamentals and/or Charles Taylor's The Internal Combustion Engine (it's in volume 1 IIRC) to find out.

The frequency isn't even that fast. For a 4-stroke/cycle 8-cylinder engine running at 6000 rpm there are only 24000 intake events per minute, which is only 400 per second--so the intake pulse frequency is only 400 Hz.


I had the privilege of studying under Dr. Heywood in the late 60s.
 
#11 ·
cliffyk said:
There are many aftermarket units that are just that, "a tube with a filter", and that's why they suck--here's why:

The air flow in the intake tube is not a continuous stream, but rather a series of pulses (with negative pressure heads, near ambient pressure bodies, and positive pressure tails) whose frequency is proportional to engine speed. In a straight tube at certain of these frequencies standing waves (harmonics) will develop and impede the flow of the pulses at those sympathetic frequencies, this is how a trumpet, cornet or trombone works. However in an internal combustion engine intake these waves cause power surging and "suck-outs" in the torque curve. The good news is that the shape of the tube can be designed to both minimse the standing waves, and even enhance the flow at certain frequencies, and provide for better aspiration. Intakes on many performance engines even have small closed end chambers called Helmholtz resonators grafted to them to control/alter the intake tract's resonance.

The engineers that know this--Ford, JLT, and as much as I hate to say it K&N--design accordingly. This is why the stock intake, which is a CAI and a good one, is not just a straight piece of rubber tubing.

All of the others, those that are just straight-walled pieces of tubing, do nothing to enhance the flow dynamics--that is why they can actually rob power at certain engine speeds and loads.
So the diameter of the intake tube and and size of filter can affect performance. Do you think going an inch smaller on the intake tube and getting a smaller filter would benefit performance or hurt it?
 
#12 ·
Making the tube any smaller than 80 mm, the ID of the MAF, will hurt performance (try breathing through a straw). The smaller you make it the greater the hit. Using nearly any diameter of straight wall tubing will also hurt performance, the level of the impact would be dependent on a whole bunch of factors.

My point above was that the intake tract is more than just a tube connecting the MAF to the TB. That is why all of the worthwhile ones (including the stock assembly) are not just "a tube with a filter"...
 
#13 ·
cliffyk said:
Making the tube any smaller than 80 mm, the ID of the MAF, will hurt performance (try breathing through a straw). The smaller you make it the greater the hit. Using nearly any diameter of straight wall tubing will also hurt performance, the level of the impact would be dependent on a whole bunch of factors.

My point above was that the intake tract is more than just a tube connecting the MAF to the TB. That is why all of the worthwhile ones (including the stock assembly) are not just "a tube with a filter"...
Understood.
 
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