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2002 chevy trailblazer_lt
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Discussion Starter #1
Ok before you guys go on and kill me, let me tell yuo where i'm from...even before they started selling on ebay or cheap knock off were made, i did my own using the standard 3" aluminim tubing, it was an "exact" copy of the k&n i had even put in a k&n filter....yeah it did sound great, but my temps were pretty much the same, now, there was one question that i dod not ask myself, does it suck more air ? WELL NO NO NO NO AND NO, don't beleive me ? do the math, the original tubing is 3.25 ALL THE WAY, from the intake to the filter, a k&n is 3", those ebay knock off are also 3", i recently was given an airaid, to my surprise it connects directly to the resonator, ok BUT the tube it uses is 3.5" so is the filter, there's a lot more sucking going on there, i did a few butt dyno tests and my conclusion is that there's a lot more low end, it sounds gruntier, and is by far "imho" better than the k&n or other 3" cai

now think about it, if you don't want to spen all kinds, just get the k&n flilter and holow your airbox....
 

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2003 chevy trailblazer_lt
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look at the stock tube. it is "ribbed" so it can flex. these ribs make the air path restrictive because of the turbulence they cause. since they are restrictive they make less power/torque. this also applies to the resonator it is made to make the air flow turbulent to make it quieter causing power loss. with the k&n intake the air path is a strait shot to the throttle body (allows it to suck more air because it is less restrictive)

compare these picks and see what i am talking about: Which has better air flow?



IMHO a intake that connects directly to the throttle body and has a smooth air path will give the most power/torque gains.

(BTW the math you talk about are some very hard calculations to many variables)
 

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2002 chevy trailblazer_ls
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Ya but doesnt the metal get hotter than the plastic therefore loosing the effect of the smoothness. Just from what I have been told.
 

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Ya but doesnt the metal get hotter than the plastic therefore loosing the effect of the smoothness. Just from what I have been told.
not at all. i have driven for an hour then poped the hood and grabbed the intake it wasnt hot at all. but they do sell an intake made out of Thermoplastic if you want.

 

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2004 gmc
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In the stock intake tube, it certainly appears to me that the convolutions are at a MINIMUM the same diameter as the rest of the tube, which matches the diameter of the throttle body. No cross-sectional restriction there, although you are claiming that turbulent flow compared to laminar flow causes some pressure drop?

Any amount of air can be sucked through any diameter pipe - it just develops a pressure drop from one end to the other. At WOT, where the intake manifold vacuum is at its lowest, I can see how you won't get the maximum possible airflow into the engine. But at anything less than WOT, getting the power you want just means the throttle body is open a bit wider than an infinitely wide intake tube.

Is anybody claiming that a 3" versus 3.25" versus 3.5" diameter intake tube is stealing more than maybe 1-2 HP to suck the air through the restricted or turbulent tube?

I thought the major benefit of a CAI was embodied in part of its name: "Cold".
 

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2006 chevy trailblazer_ls
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I will always believe in dyno sheets...



unless someone shows me that they have an intake that will give a better result, i will stick with my K&N :yes:

btw, if someone will claim that K&N fabricated this dyno sheet, try to sue them for false advertising or something :crazy:
 

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I will always believe in dyno sheets...
I believe that one as well. It's just I don't see how it affects folks like me who spend ZERO time at 4850 RPM attempting to get to 200 HP. (I know - you didn't say it was an desirable mod for everybody. :thumbsup: )
 

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Discussion Starter #8
I will always believe in dyno sheets...



unless someone shows me that they have an intake that will give a better result, i will stick with my K&N :yes:

btw, if someone will claim that K&N fabricated this dyno sheet, try to sue them for false advertising or something :crazy:
Who the hell drives their truck at 4800 rpms ?

I know they have a better gain, you will most likely get the same gain by just changing the filter...
 

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Discussion Starter #9
look at the stock tube. it is "ribbed" so it can flex. these ribs make the air path restrictive because of the turbulence they cause. since they are restrictive they make less power/torque. this also applies to the resonator it is made to make the air flow turbulent to make it quieter causing power loss. with the k&n intake the air path is a strait shot to the throttle body (allows it to suck more air because it is less restrictive)

compare these picks and see what i am talking about: Which has better air flow?



IMHO a intake that connects directly to the throttle body and has a smooth air path will give the most power/torque gains.

(BTW the math you talk about are some very hard calculations to many variables)

I completely agree with you on the turbulance part, but take a close look at the resonator box it's a straight path, as for the intake tube, just a cheap a cheap knock off for 9$,

I just don't see why i would spend 300$ on somethig that gets you nothing
 

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2007 chevy trailblazer_ls
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Good call pjaneiro. After paying closer attention to that dyno sheet, I think you and Roadie are right. Who drives around at 4800 rpm anyways. looking even at the lower rpms how much gain is there-2-4 hp? I think I will stick with just my filter and go with the leather seats this spring.:m2:
 

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Discussion Starter #11
not at all. i have driven for an hour then poped the hood and grabbed the intake it wasnt hot at all. but they do sell an intake made out of Thermoplastic if you want.

I am sorry i can't beleive that, my intake was made of aluminum same one as the k&n, same as all the otehr ones, those thing aren't "COLD AIR INTAKES" but more like hot sucking extra gas gussling intakes, even with the best shields, if it's not getting it's air from a direct outside path, it's also useless in my opinion, i ran my logger with all three recently, my cai, the airaid and the original, winner with the coldest air was the airaid, why ? i think it has to do with the bigger pipe and that it's made out of some sort of plastic, my cai was clearly the looser here, all aluminum , that thing soaked up the engine heat like crazy, and it was shieled by the hollowed out box, then original intake system with a drop in k&n, not as much "grunt" and the butt dyno did notice a bit less torque, but then again, it might just be because of the sound...
 

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Discussion Starter #12

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I dont know if it is just me but if you take a look at the dyno sheet there are 2 lines...

RED is with the K&N and BLUE is stock

Starting from 3500 rpm there is already an increase in HP

the "9.29" is the PEAK HP gained at the specified 4800 rpm.

please guys try to analyze the graph first before making comments about it :bonk:

 

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please guys try to analyze the graph first before making comments about it :bonk:
Please guys try not to insult the engineers before assuming we're idiots.

I thought one important part of the discussion was about intake tubes, their cross-sectional area, and turbulence caused by interior roughness.

Since the dyno chart changed both the tube and the filter from stock, there's too many variables to separate the tube effect from the filter pressure drop. An interesting chart for a discussion about tube physics would be one where that was the only changed variable. I don't think that data's been taken, but I may be wrong.

I see there's a difference even at 3500 RPM, and I can extrapolate backwards. But for me personally, I spend almost no time even at 3500 RPM, and certainly wouldn't notice 10 HP difference in the 1/2 second I might be there before a shift. Personally, I'm looking for low end torque for the trails, and good mileage for the drive to and from them. That's all. YMMV.
 

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Please guys try not to insult the engineers before assuming we're idiots.

I thought one important part of the discussion was about intake tubes, their cross-sectional area, and turbulence caused by interior roughness.

Since the dyno chart changed both the tube and the filter from stock, there's too many variables to separate the tube effect from the filter pressure drop. An interesting chart for a discussion about tube physics would be one where that was the only changed variable. I don't think that data's been taken, but I may be wrong.

I see there's a difference even at 3500 RPM, and I can extrapolate backwards. But for me personally, I spend almost no time even at 3500 RPM, and certainly wouldn't notice 10 HP difference in the 1/2 second I might be there before a shift. Personally, I'm looking for low end torque for the trails, and good mileage for the drive to and from them. That's all. YMMV.
If proving a point is insulting then I'm sorry.

1. The OP mentioned about "butt dyno" and such that is why i provided a dyno sheet.

2. After provision of the dyno sheet, a couple made a comment about who will drive their TB in 4800 rpm

Soooo... i mentioned that the HP gain is not just in 4800 rpm and above. it starts from 3500 (based from the graph)

Btw, i have a Bachelors Degree under my belt too so we are both professionals. nobody is calling anyone an idiot :yes:

Anyhow, i hope someone will provide a dyno of an intake with the K&N filter only for comparison purposes. As far as complete K&N CAI is concerned, there is in fact a HP gain even with the heat absorption.

Maybe a full CAI will be most useful for highway driving where you need some "extra" HP and torque for passing and the high air flow will help lessen the heat soak from the engine bay. IMHO
 

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... mentioned about "butt dyno" and such that is why i provided a dyno sheet....
Agreed. As we used to say: In God we trust - all others bring data. I still can't believe they're selling those punched aluminum disk intake airflow swirly tornado gadgets. :dielaugh: :hissy: :hopeless

 

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Discussion Starter #17 (Edited)
I dont know if it is just me but if you take a look at the dyno sheet there are 2 lines...

RED is with the K&N and BLUE is stock

Starting from 3500 rpm there is already an increase in HP

the "9.29" is the PEAK HP gained at the specified 4800 rpm.

please guys try to analyze the graph first before making comments about it :bonk:

3500 rpms....ok i'll bite, are you running 22" overall wheels on a 4.56 gear ratio ?


most of us stay in the 1700-2000 rpms, I am not saying they don't work, i'm just saying that in the "real" world they add nothing, use the 300$ on a tune or something else that will actually give you back what you spent...

Also if you look closely again, the k&n runs hotter, 81.85 for stock and 86.74
 

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Discussion Starter #18
Agreed. As we used to say: In God we trust - all others bring data. I still can't believe they're selling those punched aluminum disk intake airflow swirly tornado gadgets. :dielaugh: :hissy: :hopeless

Sorry to say, but those really do work....i know a guy that saw a guy buy one and his hyunday pony made 49mpg and was doing 0-60 in 2,9 seconds...

Now if someone had two front fenders to spare, i'll gladly think of a way of adding scoops on the sides like some other have done, we just need to move that washer fluid tank somewhere else.....in the back maybe ?

i was thinking of those hoods, wich look hot btw, but i am unsure if they really do a difference
 

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3500 rpms....ok i'll bite, are you running 22" overall wheels on a 4.56 gear ratio ?


most of us stay in the 1700-2000 rpms, I am not saying they don't work, i'm just saying that in the "real" world they add nothing, use the 300$ on a tune or something else that will actually give you back what you spent...

Also if you look closely again, the k&n runs hotter, 81.85 for stock and 86.74
that is the outside air temp. and i hit 3500 all the time when accelerating.
 

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most of us stay in the 1700-2000 rpms, I am not saying they don't work, i'm just saying that in the "real" world they add nothing, use the 300$ on a tune or something else that will actually give you back what you spent...

Also if you look closely again, the k&n runs hotter, 81.85 for stock and 86.74
my friend, did you just contradict yourself in that statement? because if they work, that means they add something right? :undecided

well, i guess we just have to agree to disagree. :yes:

sorry man, but i will never agree that replacing the filter alone and hollowing out the airbox will yield better results unless i see a dyno sheet. maybe i'm used to my line of work that anything that has no research and documentation to back it up is considered "hearsay"


that is the outside air temp. and i hit 3500 all the time when accelerating.
right and me too.:D
 
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