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Old 12-13-2011, 03:46 PM   #1
sketchman
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Choosing a CAI (Cold Air Intake)

Links are dead in the sticky so maybe this will help. Honestly I don't see a reason to mention the SRIs(Short Ram Intake). There is plenty of info on here about those. I assume because they are cheap or whatever, and that's fine but this is for those interested in going all the way with it.

I see a lot of people recommending the Fswerks Cool-Flow intake. So it is popular. It uses 3" steel piping from filter to MAF housing where it is abruptly downsized to 2.5" piping. It then is abruptly upsized to 3" after the MAF housing and continues on to the throttle body. It starts at about $222.00 shipped from:
Have to copy and paste - http://fswerks.com/fswerks_coolflo_air_intake.htm


The K&N 57-2559 also transitions from 3" to 2.5" at the MAF location and then back up to 3" for the throttle body inlet, BUT there is a key difference. The transitions are FAR smoother than the Cool-Flow which is better for flow. Plain and simple. Amazon has it for around the same price range as the Cool-Flow too. It's $238.40 shipped as of now.
http://www.amazon.com/57-2559-Fuel-I...3810584&sr=8-1


The 3rd and final choice I'll mention is the K&N 69-3512TP (also available in red). It is a straight 2.5" size from filter to silicone adapter where it is upsized to 2.75" at the throttle body to fit it. It is the cheapest available AFAIK when considering direct bolt-on CAI setups. Coming in at only $182.69 from Amazon shipped for free.
Link and pic.
http://www.amazon.com/69-3512TP-Typh...3811207&sr=1-1


So which is the best? It would take more words(and knowledge) than I have to explain fluid dynamics in detail, but I do understand the basics, and I will explain in simple terms 2 that relate to this mod.

1. Bernoulli's Principle(A very basic version of it anyway.) - When flowing air speeds up it's pressure decreases. When flowing air slows down it's pressure increases. When flowing air has to go from a 3" pipe to a 2.5" pipe it HAS to speed up. When going back to the 3" pipe it HAS to slow down. That process happening in the middle of your intake pipe is bad for flow.

More info here:http://en.wikipedia.org/wiki/Bernoulli's_principle

2. Smooth transition vs an abrupt transtion in pipe size - Look at how abrupt the transition is on the Cool-Flow. Then compare it to the black K&N. Not only will you still get the pressure changes with either one, but with the Cool-Flow it happens too abruptly to promote a smooth change in speed and pressure which causes turbulence. Again, not something you want in your intake pipe.

To make it even simpler. The MAF location is 2.5" and the MAF itself blocks some of that flow. Making the piping on either side of the MAF location bigger achieves nothing good for flow.

Bottom line? All 3 intakes will be better than stock, but which one makes the most sense? Yo-Yo changes in speed and pressure are bad for flow. Turbulence is bad for flow. One consistent size piping from beginning to end is best. And just so happens it's cheapest too. Win win.

Thanks to all so far that have helped with this. More to add later on, I'm sure.


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Lemme splain. No, is too much. Lemme sum up. The flow no know where I go.

Last edited by sketchman; 02-01-2012 at 04:02 PM. Reason: More info and keeping my opinion to more of a minimum. :)
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Old 12-13-2011, 06:15 PM   #2
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It's an informative post but also mostly opinionated. Ideally, if we could have all three of these dyno tested on the same vehicle back to back, that would put this to rest.

The goal of any after market intake is to create less restriction and better flow, which all of these surely do but with out proof to which is the best its not fair to say one is better than the other


Also, links to FSwerks' website never work from here. Who ever is interested should either google it or just type in fswerks.com
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Old 12-14-2011, 04:01 AM   #3
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Ideally, if we could have all three of these dyno tested on the same vehicle back to back, that would put this to rest.
That would indeed be ideal, but we don't have that unfortunately.
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Last edited by sketchman; 12-23-2011 at 07:33 PM.
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Old 12-14-2011, 10:12 AM   #4
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What is the diameter of the stock MAF tube?
From what you post the TB inlet is 3" correct?
I have an '06 ZX4 and '07 ZXW (PZE) and am looking for info.
I was looking at doing a 3" elbow and a cone filter off the MAF, but some post that the lower end of the MAF is larger than 3".
When I have gone searching I haven't found items that are listed specific for these vehicles, thus I don't want to order a bunch of stuff I end up sending back and any of the local places do not have much on the shelf to look at.
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Old 12-14-2011, 11:06 AM   #5
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Quote:
Originally Posted by sketchman View Post
That would indeed be ideal, but a VERY basic understanding of airflow plus common sense would put it to rest as well.

So maybe someone needs to address a couple basic ideas. So be it.

1. Bernoulli's Principle(A very basic version of it anyway.) - When flowing air speeds up it's pressure decreases. When flowing air slows down it's pressure increases. When flowing air has to go from a 3" pipe to a 2.5" pipe it HAS to speed up. When going back to the 3" pipe it HAS to slow down. YOU DO NOT WANT THAT PROCESS HAPPENING IN THE MIDDLE OF YOUR INTAKE PIPE. This is very simple logic.
I work with a lot of different sensors on machines. For a lot of Flow and Temp sensors they specify you need a certain amount of straight length pipe on both sides of the sensor for proper operation, I am sure that also applies here, sometimes listed as a certain length or a certain number of pipe diameters before bends or transitions.

Same principle different applications.

I wonder if the stepping of the size in the tube follows the principle they use in Air Conditioning, where the expansion on the output causes a cooling effect??
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Old 12-14-2011, 12:10 PM   #6
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First I want to say I do like the information you are providing sketchman and hopefully this discussion does stay on track (sometimes these threads go down fast)
Quote:
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When going back to the 3" pipe it HAS to slow down. YOU DO NOT WANT THAT PROCESS HAPPENING IN THE MIDDLE OF YOUR INTAKE PIPE. This is very simple logic.
Isnt this always going to happen though? The maf is more narrow than the throttle body, so doesn't this happen to some extent in all of these CAIs?. Or is it more a case of which one does this the most efficiently?

Quote:
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2. Smooth transition vs an abrupt transtion in pipe size - Look at how abrupt the transition is on the Cool-Flow. Then compare it to the black K&N. Not only will you still get the pressure changes with either one, but with the Cool-Flow it happens too abruptly to promote a smooth change in speed and pressure which causes turbulence. Put simply, the Cool-Flow's design is just too abrupt to promote smooth flow. The best design of the three is to just use one size from start to finish.
I can see how the black K&N does this transition more gradually but the silver one has no transition until it connects to the throttle body and then immediately goes to 3" (or how ever wide that opening is at the TB.) Wouldn't this cause the same issue as why you dislike the FSWerks design? How much of a noticeable difference do you think there is between these CAI's and any potential gains/losses?

From my point of view, I cant see any having much of an impact or one performing noticeably better. So it would make sense to simply buy which ever one you can find for the best deal (or personal preference)
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Old 12-14-2011, 02:53 PM   #7
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Quote:
First I want to say I do like the information you are providing sketchman
All I want to do is spread information, so that's cool of you to say.

Quote:
Originally Posted by rambleon84 View Post
Isnt this always going to happen though? The maf is more narrow than the throttle body, so doesn't this happen to some extent in all of these CAIs?. Or is it more a case of which one does this the most efficiently?
Sort of. But one transition is better than 2, and having 1 transition at the throttle body is better than having 2 right at the MAF location. The MAF itself already is in the way of flow by design. Adding more inefficiency at that point in the intake tract cannot be good.

Quote:
I can see how the black K&N does this transition more gradually but the silver one has no transition until it connects to the throttle body and then immediately goes to 3" (or how ever wide that opening is at the TB.) Wouldn't this cause the same issue as why you dislike the FSWerks design?
See above.

Quote:
How much of a noticeable difference do you think there is between these CAI's and any potential gains/losses?
I honestly don't know. I did do a little calculation based on K&N provided dyno charts for their intakes on a 2.3 vs. Fswerks dyno charts for the 2.0. I factored in the percentage difference that should be caused by the difference in displacement of the engines, and by those calcs you'd be kicking yourself if you paid more for the Cool-Flow, BUT those were just for giggles. Not real world back to back dyno runs, so.....

The difference in added HP was about 5.1 in favor of the K&N, BUT again not real world numbers. Though do think about this. 5hp doesn't seem like a lot, but when you consider the Fswerks adds 5.9hp (per their provided dyno charts) and the K&N should add 5.1hp more than that, it's a big difference percentage wise.

Binzer, I don't really know anything about the 07 and older. Never messed with them, sorry.
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Lemme splain. No, is too much. Lemme sum up. The flow no know where I go.

Last edited by sketchman; 12-15-2011 at 03:21 AM.
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Old 12-15-2011, 10:59 AM   #8
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Quote:
Originally Posted by sketchman View Post
Binzer, I don't really know anything about the 07 and older. Never messed with them, sorry.

My problem when searching is "Sorry, there are currently no items in this category for your vehicle selection. ".
My car is a 'first generation' with regular tb and cables to it, don't understand why the searches turn up 'nothing fits that car'.
I know there is one performance shop near work, not sure if he has any stuff for the 'small' cars, he was a former Drag Racer.

The K&N model that fits is a piece of flex hose(57-0595) , Airaid does not list one, only one I found is the fswerks, but I only want the tube, have rest of stuff.
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Old 12-15-2011, 03:47 PM   #9
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my question is, for us 2nd gen Duratec owners... you know those SRI's that re-use the factory intake snorkel/duct ...could we count that as like a CAI of some sort if its still doing its job... outside air going in it and straight to the filter?? i've only seen 2 that re-use it.
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Old 12-15-2011, 04:25 PM   #10
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my question is, for us 2nd gen Duratec owners... you know those SRI's that re-use the factory intake snorkel/duct ...could we count that as like a CAI of some sort if its still doing its job... outside air going in it and straight to the filter?? i've only seen 2 that re-use it.
Well the snorkel does go pretty far into the fender and exits towards the driver's side window. not sure how much air you would be able to get from it versus having larger piping and filter how the traditional CAI's do.

Here is the view of the stock intake without the front quarter panel or bumper on:

Unless you had suction on that snorkel, i dont think it would be getting much air.
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