Custom Cold Air Intake Help

[Ron Burgundy]

Hello!

I've been thinking about making a cold air intake. Essentially, I'd like to remove the stock air box, air filter, and resonator and relocate a conical air filter outside of the engine bay to where the resonator used to be.

The gains (if any) will be nice yes, but i'm also doing it for fun and the experience.

Anyone have any input? Has anyone here ever done it before? What are the best materials to use? Does the length from the throttle body to the filter matter? MAF Relocation issues?

Thanks for the help!

[themadscientist]

Save yourself all that trouble and work on a scoop that feeds into your factory air box.

[Ron Burgundy]

Do you have an example? Like pictures from under the hood?

[Razi]

I know that on the S13 240sx, the intake box has a tube that goes into the empty space behind the bumper to suck in cold air.

Something like that would be quite effective.

Also the S14 240sx has a tube that goes to the front grille which is good too.

[Ron Burgundy]

Something like this?

[Razi]

Yeah, I'd hook that type of stuff up into the stock intake so it can suck the cold air in.

[Ron Burgundy]

Performance wise you think that would be better than moving the filter out of the engine bay and directly behind that foglight grille?

[Razi]

Moving the filter out might be better, but if you do I suggest making a splash shield of some sort.
You don't want your engine to suck in water!

[Ron Burgundy]

Lets say I do decide to move the filter out of the engine bay...

The length of the stock intake would have to be extended.
-What effect would the extended length have?

I cant bend pipe myself, but perhaps I will get it bent at a shop. If not it looks like I should be able to put one together using parts found here: http://www.spectreperformance.com/. Here is an example of an intake on a Pathfinder using Spectre parts:



The arrows at the bottom right of the picture above indicate where I'd like to send a pipe through as done in the picture below (not a Pathfinder)



...and come out behind the left fender/wheel well like the picture below:



Ultimately acheiving this (more or less) design:



Though there is an opening fairly close by (the fog light grille pictured a few posts above), the car is fairly high off the ground as it is, and the most water we hit here in CA is a big puddle here and there....BUT just to be safe, I could always go with something like this: http://www.racinglab.com/injen-hydro-sh ... ilter.html

Questions:

1. Does the MAF have to be relocated closer to the filter (behind the fender)? If so, how would I go about extending the MAF wiring?

2. If the diameter of the pipe the MAF enters is the same, I shouldn't experience any problems....right?

3. Does anyone see any potential issues that may arise from this setup?

Thanks again for all your help!

[darens13]

i wouldnt mess with moving the maf. i have have heard that the maf is supposed to be a certain distance from the intake manifold.

if the diameter is the same no worries, even if it were larger than stock entering the maf would not be an issue, a bottle neck effect, but it "it aint rocket surgery".

i dont see any issues, as long as you arent sucking up water.

it seems like you are looking to spend a few bucks on this, i just cant help but think you will be disappointed though, as you probably wont feel notice gains. when i had my stock airbox i just cut some 3/4" holes on the bottom side, didnt notice anything but it sounded throatier. good luck though.

[Ron Burgundy]

Very cool thanks for the input!

So maintain the same distance from the manifold but distance from the filter shouldn't make a difference?

It's more for the fun to be honest with you and the sound alone will be worth it. I've never seen it done on a Pathfinder and I think it'll be a fun experience.

[darens13]

i cant imagine there would be any difference with distance from the filter to the maf, but yeah keep it the same distance from the intake manifold. have fun with it, i like seeing people put something like this together rather than just buying something similar and paying a lot more.

[Ron Burgundy]

Well hey I really appreciate all the help, and i'll be sure to post some pics when its done (hopefully within a month!)

Thanks again! And please if anyone has anything else to contribute, throw it in!

I might have more questions as I go through the motions...

[Pathofinder]

Does the distance from MAF to throttle body really matter?

[Red coupe]

If you want to make one, go for it.

Input: Its a tube that connects to a filter, make that.

Work with as cheap of material as you can so you can try different lengths and filter locations.Once you get it down learn to fiber glass and make a foam core. Use flexible joints to allow for vibration.

Does the distance from MAF to throttle body really matter?

It would help to have smooth air flow where the meter is trying to read so that it doesn't pick up a ton of noise.

[troskinatior]

Throw a burito in it

[Chaotic_Warlord]

I wouldn't use metal (not even aluminum) because it would just defeat the purpose of what you are trying to do. You still have to feed the piping into the engine bay so that you can attach it to your intake manifold and metal would just allow for heat soak. You could wrap it in thermal wrap, but then it would just be ugly and the thermal wrap would lock in the heat from the outside air, especially in the summer. You also don't want to have your filter to close to the ground or sticking out of the car otherwise you run the risk of hydro-locking your engine.

If you're going to learn to fiberglass, then you might as well learn how to work with carbon fiber. CF would not only be lighter and stronger, it would be more resistant to heat soak and give your intake a much better look in the end.

Also keep in mind that the longer the run the air has to make to get from the filter to the intake manifold just defeats the purpose of having a CAI. There's a lot of science and engineering that goes into intake design, and while it might not seem to practical or good for performance there's a reason behind Nissan's intake design. If your CAI is longer than the stock intake then you will see little to no performance gains. The shorter the better, this way you not only get the coldest airflow going into your intake, but the air pressure is still high enough that you'll actually see performance gains and won't see the much effect of any heat soak that will occur.

That's just my $.02

[Ron Burgundy]

Thank you! This is the kind of information I was looking for!

I wouldn't use metal (not even aluminum) because it would just defeat the purpose of what you are trying to do. You still have to feed the piping into the engine bay so that you can attach it to your intake manifold and metal would just allow for heat soak. You could wrap it in thermal wrap, but then it would just be ugly and the thermal wrap would lock in the heat from the outside air, especially in the summer. You also don't want to have your filter to close to the ground or sticking out of the car otherwise you run the risk of hydro-locking your engine.

If you're going to learn to fiberglass, then you might as well learn how to work with carbon fiber. CF would not only be lighter and stronger, it would be more resistant to heat soak and give your intake a much better look in the end.

The filter would be fully enclosed (with the exception of the foglight grille opening seen above) and quite some distance from the ground. I would even enclose it with one of those "Hydro Shields" or something similar just to be safe.

For the time being, I don't plan to learn how to fiberglass (maybe one day...). What other materials would your recommend if metal is no good? PVC?

EDIT: I've also read from a few places that because the air spends very little time in the intake itself, the materials used often don't matter. Yes? No?

Also keep in mind that the longer the run the air has to make to get from the filter to the intake manifold just defeats the purpose of having a CAI. There's a lot of science and engineering that goes into intake design, and while it might not seem to practical or good for performance there's a reason behind Nissan's intake design. If your CAI is longer than the stock intake then you will see little to no performance gains. The shorter the better, this way you not only get the coldest airflow going into your intake, but the air pressure is still high enough that you'll actually see performance gains and won't see the much effect of any heat soak that will occur.

Even if the length is just slightly longer? Say...6 inches or less? Would you say a shorter intake located in the engine bay might be better performance wise? Other ideas?

Thanks! Much appreciated!

[PapaSmurf2k3]

Can you make the intake out of aluminum or steel? Sure, will it be as good as an insulator? No.

Making the length slightly longer isn't going to hurt you THAT much, so long as its relatively big tubing. Bends and bottle necks will hurt you for sure though.

[Ron Burgundy]

Ok thats good to know. I drive a Pathfinder so i'm not expecting it to be a racecar after all is said and done.

Just a little better throttle response, acceleration, and throatier sound would be nice.

There might be a few bends here and there, but i'll avoid them as much as possilble.

Other materials your would recommend?

[Red coupe]

Ok thats good to know. I drive a Pathfinder so i'm not expecting it to be a racecar after all is said and done.

Just a little better throttle response, acceleration, and throatier sound would be nice.

There might be a few bends here and there, but i'll avoid them as much as possilble.

Other materials your would recommend?

We have used even just a large section of silicone coupling to replace part of the miata's intake tubing/move the filter to the back of the engine compartment. Works well other then the fact that it wont support weight.

[PapaSmurf2k3]

Other materials your would recommend?

I remember seeing some flexible tubing in McMaster Carr. They sold 2 different versions, one with a ribbed interior, and one with a smooth interior. Get the smooth kind for better flow.

[darens13]

it sounds pretty okie but woundnt pvc pipe be an awesome insulator? you can buy the bends at any hardware store, its pretty tough and cheap.

[Ron Burgundy]

Ok starting to get some good ideas here.

McMaster Carr has about a million different types of tubing. I don't even know where to begin!

As for PVC pipe, I read its an excellent insulator, however, in some applications it may not be able to withstand the heat and may melt. It was sort of half and half. Some say it worked great, others said don't bother.

I think i'll head down to Home Depot/Lowes and get some ideas...

[darens13]

i certainly hope your engine bay doesnt get hot enough to melt plastic, what is your stock air intake made out of?

[Ron Burgundy]

The elbow where the intake connects to the throttle body is made of rubber (silicone?) as well as a connection down the line.

The rest is ABS plastic I believe...

[PapaSmurf2k3]

The McMaster Carr stuff is pretty flexible, but strong. I think some people even use it for turbo piping. It can withstand 15 PSI or something. PVC is rigid. The McMaster stuff is also a good insulator. Anything plastic is going to be a pretty good insulator. If you can figure out exactly what material it is (or even get close), you can check all the material's properties in this quick and dirty Engineer's tool:
www.matweb.com

[Dattebayo]

McMaster Carr is expensive, forget about that.
Stay away from Sprectre tubing, only use the couplers.

There has to be a company somewhere that has made an intake for your VG33E...

[mdawg4x4]

There should be a kit similar to this available for your 3.3 Pathy.


I don't know if there is NISMO available, but my son has a NISMO CAI on his 03 Frontier 3.3.

[Dattebayo]

Nismo is also ridiculously expensive!