Worst of the test group! Almost the worst even without it's air filter.

http://autospeed.com/cms/A_0073/article.html

James

 

"goes out and buys k&n for new Turbo II before even starting car"

 

I've been saying that for years.

Some cars come with factory airboxes that are worth keeping and modifying. Ours don't.

 

It may not flow well but it is at least a cold air intake ... Replacing it with a cone without proper sealing/ducting to the outside is ... not the best idea.

Hugues -

 

I don't know if its the same as the FC, but you do know that the article is talking about the FD airbox, right?

-Joe

 

Um, no it's talking about an FC airbox...look at the picture. FD's do not have the same looking box as FC's and the pictured box is definitely for an FC. I'm not sure why this is such a surprise as people have been seeing a load more boost on a TII simply by taking out the stock airbox and using a simple TID. Conversely, people without ample fuel/boost control often use the stock airbox in effort to keep boost down and save their motors.

 

Did you read the article? This is directly from the article:

"Mazda 1992-1997 RX7 Turbo"

Its written right above the few paragraphs that describe the airbox.

-Joe

PS...and yes I do agree that looks like an FC airbox. However, according to them, the results came from an FD airbox.

-Joe

 

They just have the wrong years indicated. As stated, that's a FC box. The FD uses the same filter, so no matter, the designs leave a lot to be desired.

 

I'm sure they just had the wrong year listed...if they had an FD box tested why use a picture of an FC box?

 

Well the test results are no surprising... ditch that box for a cone filter now!

 

Don't expect big gains at ALL on an NA as it seems to be more a mod that frees up space under the hood as opposed to power. If your car is a TII, be aware that with an exhaust you will hit fuel cut which can damage your motor. There are some expenses that come along with an exhaust and intake on a TII and at the very least they are:

-fuel cut defenser
-upgraded fuel pump
-ported wastegate

A fuel controller on this setup is ideal (think SAFC).

 

Not very much information there! I'm not disputing the findings and I agree with the earlier post that says: A cone filter hanging in the hot engine compartment is a poor substitute!

I don't know if anybody has tried to manufacture a replacement top to the stock box that adds a short route to the cold air OR a CAI that uses something other then a cone filter?

It shouldn't be hard to incorporate these specs! Does a cone filter even have this much filter area? The stock one is very generous in size

 

Hmmm, upon reading it further, it's funny how they talk about expensive filters...

You can either buy a cheapo filter at an autoparts store for about 11 bucks, or buy a K&N permanent replacement for about $50 and never replace it again. I'm wondering where they buy their **** at.

 

What i was thinking of doing: I have a donor 92 Eclipse that I need to find time to get to the boneyard, however, it has a nice cone air box (Stock), with a K&N air filter (newish). i was thinking of modding that, so that the airbox and filter were in the same general location, and then fabbing a snorkel out of fiberglass or something to go straight down, and open with a inlet mouth undeneath the belly pan (pointing foward, obviously). Think that this would work well?

 

They've quoted the wrong years, that's all. If you read the description of the airbox, it's pretty obvious they're talking about an FC one:

"A large flat box, the Mazda unit is 360 x 330 x 230mm. It uses a filter with an area of 500 square cm. The top-mounted inlet air duct is 110 x 40mm and is divided into two by a vertical separator panel. The outlet duct is 70mm in diameter and draws air from a recess below the main box body. No less than eight bolts are used to hold the box together. "

And AutoSpeed take all their own photos. They took a photo of the airbox they tested, which again is obviously an FC one.

For starters, it's an Australian site and the prices are in Australian dollars, so your prices are meaningless. And the point they're making is that the filter is relatively expensive compared to others in the test and other filters in general.

That's a good idea, but only if it's a good airbox. You can really only tell that by testing. But if you read the many AutoSpeed articles on modifying airboxes you'll see that this technique can work very well. The problem you're most likely strike it fitting a decent-sized airbox under the bonnet. The reason the stock box isn't very good is that it's shaped to fit under the FC's very low nose.

 

I'm not surprised that a V8 filter box was designed to flow more air, it only has 4x the cubes

 

it seems that the stock air box for fc's flows pretty well without a filter compared with the rest of them, does that mean a k&n filter would be a good idea or is it best just to use a cone filter with some sort of way for it to get fresh air? its hard for me to tell as ive done it both ways with two of my fc's. i modded the top of the stock airbox with a k&n on my s4 and went cone filter on my s5 with some plumbing for fresh air to reach the filter but i cannot say which one is best. they both seemed to do their job well.

 

why would you mod the top of the box...wouldnt it just be sucking on the hood?

 

Interesting question: Why are we comparing the flow rates of a filter box designed for a 1.3 liter engine to the flow rates of one designed for a V-8??? Four times the displacement should have a box that flows four times the air, after all...

 

Actually a rotary flows like a piston engine of nearly twice the displacement, about 2.5L for a 13B.

TriangleMan and Wayne, I think you've missed the point of the article. It was so people who have no airbox (i.e. converting from carb) or who want to upgrade thier airbox to a better one have some comparison figures to use when deciding which one to use. It's not about comparing rotary to V8.

Besides, you can't just assume that an airbox from a V8 will flow twice as well as one a one from a rotary, and the tests prove they don't. As I mentioned, airbox shape has as much to do with packaging as engine airflow, and a V8-powered sedan is going to have much more room for an airbox than a small sports car.

 

Fuel cut is designed to save your motor, it cannot damage it.

 

Satire?

 

Fuel cut is an OEM safety measure but it can do damage because it is, more or less, a momentary lean condition. You can NOT simply slap on an intake/turbo back exhaust on a TII and expect the fuel cut in the ECU to save you. Keep boosting around and hitting the cut and I guarantee you'll grenade your motor.

 

It does not create a lean condition, it cuts all fuel... your motor needs fuel to combust. With no fuel, there is no combustion, therefore no lean condition.

 

What he said. The ECU does not reduce the amount of fuel injected into the rear rotor, it simply stops injecting it at all. You can't have combustion without fuel, and you can't have detonation either.