Devon_RX-7

I am considering taking this Cold Air Box and switching over to a CAI. I like the looks of the Cold Air Box, but I am sure the performance differance would be better with a CAI. Which do I go with? Here is my current setup: Any thoughts will be appreciated!

Thanks!

Mason Rx7

This has been discussed ard argued a million and a half times.

If you do a little searching you will find the thread I'm sure.

I would get a real filter too. I'm pretty sure those filters don't work too well.

Black91n/a

There's probably so little power differance that you can't feel it and would be barely able to measure it.

NZConvertible

They're basically the same thing. A cold air intake is any set-up that ensures only outside air enters the engine, not engine bay air. A cold air box is just what seperates the filter from the engine bay, but if it doesn't have a duct or similar to allow outside air in, it's not a cold air box, it's just a box.

What's in that photo is not a cold air intake or a cold air box. Not only is there nothing feeding outside air to it, it has huge gaps all around it and will not prevent hot engine bay air entering the filter.

1987RX7guy

iTrader: (3)

A fully piped fresh(cold) air intake is the best solution. Why the hell do you need a box when to make it have fresh air you still need a further duct to the outside anyhow? Make the filter be outside the engine bay from the begining, btw get that nasty ricer filter out of there. Pick up a K&N or Apex'i filter.

gingenhagen

since the stock air box is separate from the engine bay heat and is piped to take in outside air, is it then better than anything short of a filter sitting outside of the engine bay?

NZConvertible

Because it's nice to be able to inspect and clean the filter without having to remove a wheel...

Given how restrictive it is, no. And it is affected by engine bay heat.

gingenhagen

What exactly is it that makes it so restrictive?

RSVampire

the fact that it has more bends (most of the time) than a cold air setup and some of the plastic has ribs which disturb the air flow into the engine. Even if the piping isn't restrictive you gain horsepower by sticking a good cone filter with good piping instead of the stock setup so obviously there is some sort of problem with the stock system..

Mason Rx7

The stock system is built to quiet down the sound. By doing so they also restrict airflow. The stock design isn't built to flow. It is built to quiet down the intake.

gingenhagen

So you're saying most of the restriction lies in the TID then? So then replacing the stock air box with a cold air box or cold air intake has a very minimal effect?

NZConvertible

A lot, but not most.

Not at all, it makes significant difference if done right.

arghx

iTrader: (3)

I have that cold air box. It actually does seal with the hood when it's closed and I think it does insulate your filter from engine bay heat at least some. I'm not sure how much power I got from it but it's better than nothing. It's essentially a less ghetto version of the FC3S write up : http://www.fc3s.org/how_tos/engine/cold_air_box.html

jkimbro

iTrader: (3)

But that filter has carbon fiber yo! That's gotta be worth 10 horses.

1987RX7guy

iTrader: (3)

Who said anything about a ghetto fenderwell CAI?

ddub

Mine goes through next to where the washer fluid bottle is (still plenty of room for bottle too), and I can take the filter off of my car without jacking it up or removing a wheel. This is also with a farily lowered car. It's all about placement.

NZConvertible

Maybe it does, but I can see huge gaps all around the sides so it will be pretty ineffective at keeping out engine bay air.

In case you hadn't noticed, most of the pod filters on this forum that've been moved out of the engine bay are in the fender.

How about some photos of where the filter is? I can't see the filler neck for the washer bottle in the photos you posted in the other CAI thread. I also can't see where you could put a pod filter that doesn't require jacking the car up. Educate me...

ddub

I do not have the washer fluid bottle anymore, but I did at one point. Removed it a while ago, you can see the stock hole for it in two of the pics below, though.

ddub

Oh and the jacking up thing. I've worked on it, and in fact put that filter on and took it off a bunch of times when I was building the new piping for my setup, all with the car sitting on the ground. I was just laying on my back and could easily reach up there with my ratchet and deep socket 8mm to undo the clamp. No problem at all.

In fact, when I was putting the filter on and needed force pushing the pipe/filter together, all I had to do was kneel on the ground with one arm in the engine bay holding the pipe, and one arm reaching from underneath holding the filter. I really didn't have any trouble doing this.

nzs4

to me the best setup is a completley sealed cold air box with sealed ducting from the front bumper. think how much presure is on the front of the car at 100kmh that nice cold air actully gets fored into the engine to sum extent

NZConvertible

You had the filter and the washer bottle in there? That's a pretty small pod filter I guess. Mine wouldn't fit there.

So don't you have any of the plastic that's supposed to be under there? It looks like you've cut away part of the inner wheel arch liner. I'd be worried about all the crap thrown up by the wheel, particularly in the wet.

Nick86

iTrader: (1)

Cold Air Box & Cold Air Intake are essentially the same thing. What we see alot of here, is people building Heat Shields and calling them Cold Air Boxes or Intakes. From my experience, I've learned a couple things that I'd like to share.

All things being equal, air ALWAYS takes the past of least resistance. Because of this, you neet to either have a large duct in the airflow, or the filter directly in the moving air. It is for this reason that ducting air into a box via the stock snorkle doesn't work at all - period. It is nearly impossible to PUSH any air up through that system. The reason it was placed there by mazda was to SUCK air in from the engine. Unless your box is air-tight, don't expect to get any air in from that method.

I've always been a bit confused as to why people put the filters out in the open, so I tried it. While they get a shitload of air, they also get FILTHY quickly. Many people get all bent out of shape about and cry about the possibility of hydrolock while driving through puddles, but that really isn't going to happen. The main disadvantage is that when it rains, the element gets wet and becomes way less efficient - thus negating any benefits of having cold air in the first place. If you clean the filter often, and it doesn't rain much where you are - then using this system is fine.

My solution was to weld up an aluminum box that seals to the hood and ducks in air from the front bumper via a 3" PVC pipe. From what I could tell, anything smaller wouldn't give me enough air. This system has worked flawlessly for me. It shields the hot air and brings in a lot of cold air and I can clean and inspect the filter easily. The only drawback was that I had to relocate the washer bottle (to the same place on the drivers side). There is no way I could fit a tube (much less a filter) in that area with the washer bottle.

Here's mine:
https://www.rx7club.com/showthread.p...0&page=1&pp=15

Go to PAGE 5. It has the writeup and pictures there.

ddub

Yah, it fit, but it was tight. Only thing missing is the plastic for the brake duct junk pretty much, there was something broken I ripped off on part of the wheel well liner but it wasn't for spacial reasons at all.

Yah I worried about that too at first, but after living in the NW (read lots of rain) and driving it through last winter, everything under there actually stayed relatively clean. I was surprised it didn't get dirtier, even the filter was fine and just needed to be cleaned once after winter.

Black91n/a

Actually having a sealed box isn't necessary. If you have enough airflow then the cold air will always be spilling out around the edges, preventing the hot engine bay air from entering. Also, you want to be sure that the filter can get lots of air no matter if you have the headlight up or down (assuming you have a headlight duct).

Also, sucking water up into the engine is a possibility. Road and Track did it to their long term Mini, and $10,000 later it was working again. And they aren't some car hating, negligent people either.

Nick86

iTrader: (1)

A sealed box is only necessary if you are trying to suck air in, rather than having it pushed in. Sealing the box just helps when you aren't moving quickly or at all - then hot air has a harder time getting in.


I never said it wasn't possible, just that it wasn't the reason that I didn't put my filter there. Getting water in the engine is very possible, and as they showed - expensive. Of course there are those who believe that a rotary is immune to hydrolock, but that's a whole other thread.