gentlejax2

I did this with my Tbird and got pretty much as good as results as with my cone setup even though I had a heatshiedl for it.

I was going to cut a 3in. hole in the bottom of the airbox and then pipe in cold air fron the front bumper. I was also going to close off the stock duct that sits on the top on the radiator so that the air would be sucked from the freshest point being the duct below the box at the bumper.

did same thing on Tbird and I sucked in all kinds of things so I knew it had sucking pressure or whatever.

I got a flat panel K&N and will modify it .

I jsut wanted to know who has done this same thing. I am not refering to the cutting many holes in the bottom but rather a big hole with a direct pipe to the outside air.

thanks

Mike

Nick86

iTrader: (1)

Not to be an *** - but how long did your T-Bird's engine last doing that?

If you did that setup, you would be completely bypassing the filter element, and sucking all that crap directly into the engine. Not sure if it's the same on a T-Bird, but on FC's, the filter panel is right at the top of the box, and the AFM is at the bottom. It sucks air from the inlet above the filter, and then only clean air gets to the intake.

RRTEC

iTrader: (13)

ditto...^^^^^^?

SureShot

Actually Mazda did a pretty fair job by putting the stock intake snorkle in a high pressure area in a seperate air flow from the radiators.

The only obstruction is the hood prop (which I removed).

Nick86

iTrader: (1)

Here's what I mean: (Mad "Word" Skills yo)





SureShot - I'm not sure I agree with you. While yes the stock snorkle is located in a high pressure are - no air can get forced into because of the hood! The snorkle just lets cooler air get sucked from infront of the rad.

Personally, I can't understand how air would get pushed into the stock location - but that's just me.

ajsuper7

on my 87 na i had a kn filter on the stock airbox and i cut the top off of it to get more airflow. it did help but i dont know if thats the best way to do it since it would still be sucking in hot air mixed with air from the snorkle. a better cold/ram air system would have to be fabbed and it has been done just search the forum. the intake is a big restriction but its hard to modify it without doing some fab work.

allforjesus06

your design is flawed.

cut the hole in the top of the air box, flip it over.

the AFM can be used upside down, it's just when it's tilted left or right, the gravity affects the flapper.

just use the ram air function, dont use the snorkle.

your design allows clean snorkle air to come in, but the dirty ram air to go into the engine.

maybe im not completely understanding, but that's my 1 cent.

Nick86

iTrader: (1)

It wont fit like that. If the box is upside down, the AFM will now be on the other side of the box, and therefor the AFM will hit the shock tower. There's just not enough room.

But in principal it makes sense.

greenchili

your idea is probably better than just having the stock air box. It will be getting more air, but it may only be hot air which isn't that great.

When I first got my FC the previous owner took a hacksaw to the top of the stock air box. I put a K&N stock replacement, and it worked fine.

I later was able to pick up a cone filter and adapter for the AFM, and I think it seems to work a little better. My temp gauge doesn't go as high, and you can hear a much louder sucking sound.....almost like a funny little BOV. (I think this may be because I don't have any other kind of filter on the other little air hose that was attatched to the stock air box) The next step is going to make my own aluminum air box and find a better way to ram air in there. I'm thinking of doing the mod to the headlight cover, and maybe have a tube from the front bumper.....we'll see. I think it's a cheap fix, and will probably cause alot less wear on the vehicle because it won't be sucking in nearly as much hot air.

P.S. What's the best way to filter that other hose that was attached to the stock air box? I think it come's from the air pump? Would one of those cheapy little 1" cone filters from auto zone work?

ajsuper7

yeah just get one of those little air filters, works fine but gets dirty quickly.

NZConvertible

The T'bird airbox obviously has the box inlet in the bottom half of the airbox and the outlet in the top half. This is actually a very common set-up and the mods he described can have excellent results.

Unfortunately the FC's airbox works the other way around, and the depth of the top half makes it almost impossible to improve on its design. I'm actually a big fan or retaining and modding stock airboxes, as you can often get better results with less work compared to the common pod filter, heat shield and cold air duct combo. Its just not practical to do this with an FC however, unless you were to swap in a different airbox.

Here are a few examples that prove the effectiveness of this approach.

http://www.autospeed.com/cms/A_0779/article.html
http://www.autospeed.com/cms/A_0652/article.html
http://www.autospeed.com/cms/A_0663/article.html
http://www.autospeed.com/cms/A_1605/article.html

gentlejax2

Yes, I see that NZ actually understood what I was talking about as the stock airbox has an opening for the air thru the bottom naturally. I then piped in cool air from outside directly attached to the airbox.

with this the setup was airtight which is hard to due unless you can fabricate some type of box and most of us do not have lots of tools to do it right. I made a box for the Tbird out of Lexan and worked good but it wasnt airtight.

using the stock airbox and the K&N I could actually put my hand in front of my air inlet at the bumper and could feel the suction of the air . I could put a leaf in front and it would suck it into the hole.

that means it was airtight.

I figured the stock airbox for the RX could be used in the same way.

I will check it out when I have time.


No, I wasnt sucking in trash directly into the motor......

My thoughts were not about the actual RX box as I had not really looked at it much. I just yanked it off and replaced with a cone. Now I am re-thinking it based on my previous experience.


thanks for the input.


Mike Z

NZConvertible

Due to the shape of the top (intel) half of the box, it's highly unlike you'll get something onto it that'll work much better than the stock snorkel. Also, the box's outlet (where the AFM attaches) is quite a poor shape, so IMO it's not really worth putting too much effort into. We just lucked out on airbox design unfortunately.

Markus

Jason you are so correct. The factory Mazda box is crap, i am unsure why people even keep them. Hell Mazda even had problems with thier own! after years of being in a hot engine bay the earlier 86-88 style filter box would litereatly start to melt nasty black gooo all over the inside of the AFM.

You really are better off just custom fabbing a cold-air induction. For one it's not brain science, just keep in mind that the longer the inlet tube the more low end you are going to gather however lossing top end slightly. goes just the same for if you were to just bolt the filter to the TB elbow (Granted aftermarket EMS or CARB) this is by far the best place to mount the filter "power" wise, however it's a tad too hot for my tastes. My current setup is as such:

Cut slight provision into passenger side radiator/chassis metal, running LT-8 so placement of an AFM is not applicable. I had a fabrication shop mandrel bend 3" tubing from the throttle body elbow to just in front of the radiator (where coolant res. belongs). Attached to the tube is a nice and large Rx-8 KnN filter.

Icemark

In just under 20 years of working on FCs I have yet to see a single one "melt nasty black gooo"...

As well as the 86-88, is the same exact box (other than air flow meter hook up on the bottom and other minor moulding differences) as the 89-90. Even the 91 is the same plastic as the 86-88.

So I tend to think you don't really know what you are talking about on that or have had expereinces that are not from normal useage.

Markus

You are correct Mark, however i am only 21 and have only gotten a small percentage of full contact problems, troubleshooting, diagnosing ect..ect.. of FC's, damn you've been working on them since i was nearly born! lol I only ever seen a few 89-91 cars. However i know for a fact that Mazda tried useing a metal air-box in thier 2nd gen cars for a short while, but i'm not sure on which year, 87' maybe?

Icemark

There was never a metal air box... whoever told you that was radically wrong

Wanked_FC

iTrader: (1)

Every FC I've even seen whether turbo or n/a has had a plastic airbox from the factory.

Evil Aviator

That will have no ram air effect, but it may reduce the restriction of the stock air box. In the case of a stock, or mostly stock, non-turbo engine, I think it's a waste of time. IMO the stock air intake system isn't going to cause significant restriction problems until you get into TII cfm territory.

It's about time you saw it then.

NZConvertible

What the hell is that crap?

gentlejax2

my original plan was not based on the fact that the Mazda box is backwards from what I thought.

Had a ram eddect with my oldf box.

Has anyone tried to put in a different box?

Tofuball

Your idea to pipe into the bottom would work fine if you just put another filter at the end or middle of that pipe

Evil A: How did THAT happen?

Evil Aviator

I doubt it. How did you measure the ram effect?

I don't know. I have never seen it myself, either, and thats with 16 years of experience with these cars. These pictures are from Node's car. He thought it may have been a melted gasket from the filter, which is about all I can think of, too. Maybe it's from a really bad replacement filter? Here is the thread:
https://www.rx7club.com/showthread.p...hreadid=167391

Icemark

looks like a crappy air filter (probably a Fram) or a bad air pump and not a melted airbox to me

gentlejax2

looks like silicone black sealant to me the way it has a drip look to it...

just my thoughts