# how does cold air intake work?



## fondoo (May 2, 2002)

can anyone give me some feedback on how an cold air intake works? how does it increase your horsepower? i cant find any information on it. all i can find is people selling them.


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## James (Apr 29, 2002)

cold air makes more power than hot air because it is denser. there's a way to figure power per degree change but all you have to know is the basic.


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## morepower2 (Apr 19, 2002)

fondoo said:


> *can anyone give me some feedback on how an cold air intake works? how does it increase your horsepower? i cant find any information on it. all i can find is people selling them. *


Cold air is denser hence it can produce more power due to more o2 in it per given volume.

The best of the CAI's like AEM are tuned in length to resonate at a given RPM and use that effect to increase power as well.

Mike


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## fondoo (May 2, 2002)

is it suppose to sound that unusually loud? i'm just curious


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## James (Apr 29, 2002)

fondoo said:


> *is it suppose to sound that unusually loud? i'm just curious *


it will sound louder than the stock airbox if that's what you're asking... it makes a hissing sound too because of the k&n


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## Guest (May 22, 2002)

*You went over the poor kids head!*

The extension relocates the filter away from the engine bay away from the heat and in to the bumper. The air is always cooler there and at speed is readily availible. I dont know if you have noticed how hot the sentra and 200 engine bay gets but if you ever hit traffic in the rain you will see what i mean, steam just rises right off the hood. With about 65$ you can make one that is just as good as some of the ones selling. All you need is a 3" 90 deg. manderal bent U pipe. Some 2* 3" inch rubber sleaves and 4*hose clamps. 1*3/4" rubber plug opening. and a saw and a drill. You take and slide the battery tword the engine as far as you can twords the engine in the tray. Cut the U bend in half at the center of the raidiuse connect it to the mass air opening with the rubber sleave and mark where you want the hole to drop down the rest of the extension and filter. It should be right arround the back Right hand side of the batterey. There is already the stock airbox hole that is there that is small. you can either cutt a hole out or bend the edges down to open it up. Take the bumper of and measure the length and cutt the rest of the U pipe to length. Tesfit everthin and measure twice. Now for the o2 sensor u will need to find a spot on the bottom of the 3" extension that is close to the sensor (should be right at the start of the bend before the pipeing drops into the fender. Dill your hole 1/2" put the plug in and slide the sensor into place. Clamp everything down and you are ready to go... I actully had mine painted to match the car and through a NISMO sticker on it to dress it up.. i will see if i can dig up a pic....


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## James (Apr 29, 2002)

*Re: You went over the poor kids head!*



syndicate-bro said:


> *I dont know if you have noticed how hot the sentra and 200 engine bay gets but if you ever hit traffic in the rain you will see what i mean, steam just rises right off the hood. *


we haven't been getting that much rain down here in CA...


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## psteng19 (May 4, 2002)

My question is WHY does the intake make the noise it makes?


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## James (Apr 29, 2002)

psteng19 said:


> *My question is WHY does the intake make the noise it makes? *


well because the resonance in the big metal tube, it's like a big instrument... also because the holes in the filter make the air 'vibrate' b/c of the resistance, it's like the old blowing into the top of a bottle effect... except a lot higher pitch. not that noticeable tho.


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## Guest (May 24, 2002)

*Idle adjustment.*

on the top of the throttle body there is a black plastic cap. pop that cap off and you can use a screwdriver to adjust the air flow to minimalize the hissing sound, it takes some tinkering to find out how your car will like the adjustment. Some cars idles will bounce. you need to find the happy medium, the hissing will not completely go away because the filter is alowing alot more air throung and it isnt confined in an air box..


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## James (Apr 29, 2002)

what speed did you adjust yours to before the hissing stopped? I'd like to but I've grown fond of the hissing...


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## Guest (May 24, 2002)

*I adjust it when i do the timing at the track.*

It depend on the weather and how the car is running. tipicaly around 13deg for the timing and at 11-12k rpm.


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## fondoo (May 2, 2002)

*injen cold air intake pix's*

here are some pictures of the cold air that i've installed

http://www.geocities.com/cad_design2000/injen/


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## Ninety-Nine SE-L (May 5, 2002)

adjusting, the idle screw has a drawback. I turned it down and the hissing went away, but as a result, the point where the hissing stops, the idle is so low, that the car stalls whan I come to a stop. I eventually had to turn it back, to keep the engine running normally.


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## 9double8 (Jul 9, 2002)

*Re: You went over the poor kids head!*



syndicate-bro said:


> *The extension relocates the filter away from the engine bay away from the heat and in to the bumper. The air is always cooler there and at speed is readily availible. I dont know if you have noticed how hot the sentra and 200 engine bay gets but if you ever hit traffic in the rain you will see what i mean, steam just rises right off the hood. With about 65$ you can make one that is just as good as some of the ones selling. All you need is a 3" 90 deg. manderal bent U pipe. Some 2* 3" inch rubber sleaves and 4*hose clamps. 1*3/4" rubber plug opening. and a saw and a drill. You take and slide the battery tword the engine as far as you can twords the engine in the tray. Cut the U bend in half at the center of the raidiuse connect it to the mass air opening with the rubber sleave and mark where you want the hole to drop down the rest of the extension and filter. It should be right arround the back Right hand side of the batterey. There is already the stock airbox hole that is there that is small. you can either cutt a hole out or bend the edges down to open it up. Take the bumper of and measure the length and cutt the rest of the U pipe to length. Tesfit everthin and measure twice. Now for the o2 sensor u will need to find a spot on the bottom of the 3" extension that is close to the sensor (should be right at the start of the bend before the pipeing drops into the fender. Dill your hole 1/2" put the plug in and slide the sensor into place. Clamp everything down and you are ready to go... I actully had mine painted to match the car and through a NISMO sticker on it to dress it up.. i will see if i can dig up a pic.... *


Do you any pictures of the set up you built?


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## kristinspapi (Aug 29, 2002)

*let's see those pics!!!*

I'm with everyone else who wants to see pics of the CAI you made. Hell, if you were the ornry sort of guy you'd see copied instructions on EBAY like those suicide trunk lid folks.  I want to make a CAI my next mod and would love the input and I found myself reading your instructions with hope of being able to duplicate.


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## Guest (Sep 4, 2002)

1997 GA16DE said:


> *adjusting, the idle screw has a drawback. I turned it down and the hissing went away, but as a result, the point where the hissing stops, the idle is so low, that the car stalls whan I come to a stop. I eventually had to turn it back, to keep the engine running normally. *


Yeah, I woudn't screw with the idle. Pull the TPS, adjust your idle to 750 or thereabouts and be done with it. If the car hisses or vibrates bad (like mine used to with super-aggressive motor mounts) just live with it!


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## azkicker0027 (May 31, 2002)

the hissing is only at idle, why bother with it, risk of messing up idle air control valve, and setting off ck engine light, with multi-cylinder misfires, just a suggestion.........


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## LuvMyRide200sx (Aug 5, 2002)

I like the hising. Its scairs the ricers. the ones that dont know anything about cars dont know what to think.hahah and i love the gurrrrrr that the intake makes when you STOMP it.


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## Ninety-Nine SE-L (May 5, 2002)

yeah, but the growling can be a bad thing too. everytime I try to pass somebody, they either think I'm angry with them and they flick me off, of someone tries to race me. I'm really not trying to attract attention, but when I punch it...you get it.


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## Blu200SX (Jul 22, 2002)

i like it when your trying to merge and someone wont let you over so you blast it and it roars...lol...show them the horsies


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## azkicker0027 (May 31, 2002)

the hissing is the air rushing the intake manifold, with or without the upgraded intake, just a MAF, it is there, it is only eliminated by the big plastic accumulator in the fenderwell, and the volume of the air filter box, take it all out, put new stuff in, or make stuff fit, nice "forced-induction-like" hissing, then growl, then there goes the horsies, then get run-over by a herd of v8s'.........damn ponycars........and intimidate the ricers, as aformentioned....


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## azkicker0027 (May 31, 2002)

almost forgot to mention, rushing air THROUGH idle air valve...small hole, lots of air wanting through at idle........hissssss..


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## Guest (Sep 9, 2002)

azkicker0027 said:


> *then there goes the horsies, then get run-over by a herd of v8s'.........damn ponycars........and intimidate the ricers, as aformentioned.... *


Who's intimidated? Take a look at these two MPEG's from Limerock yesterday... I'd say the Gran Sport, Mustang Cobra, and M3 were pretty intimidated. The M3 you can see at the end of the first clip. The second clip was on the very next lap. 

I'm not intimidated by any V8's 

But then there's my spin... the third clip. I was being intimidated by a better-handling Miata being driven by a better driver. Lucky not to have flipped the car the way I went sideways in the grass

Enjoy

http://www.kieranlavin.com/pictures/LRP1.MPG
http://www.kieranlavin.com/pictures/LRP2.MPG
http://www.kieranlavin.com/pictures/LRP3.MPG

It'll be a few minutes as they're uploading now


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## azkicker0027 (May 31, 2002)

i meant going straight, but it's cool..........


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## Guest (Sep 11, 2002)

azkicker0027 said:


> *i meant going straight, but it's cool.......... *


You're only allowed to pass when going straight 

You should see the video I have of the Slantnose 911 shooting flames out at me! Till I passed him!


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