thoughts on fogging...

[maherbaz]

I have been thinking a lot lately about fogging my air box. Everyone on here seems to like it a lot. I am no engineer, so the logic seems sound to me:

Find a source of cold air, and force it in. This makes the engine burn more fuel, and thus more power.

But the more I think about it, the less sense it makes...
First, about the "forcing." On Fogg's website, he compares the air flow at several RPM levels. This shows a dramatic increase in air flow even at low RPMs. I can't imagine the car traveling fast enough at this RPM to force much air all the way from the brake line, up the tubing, into the air box, etc. Also, I read in a post on here that some people leave the stock intake in place, and cut another hole in the air box for the hose to the brake duct. Let's assume that at high speeds air is really able to be forced up the hose. If air was being forced up the "fogged" tube and merely "sucked" in through the stock tube, no air should be traveling in through the stock intake. The forced air coming from the "fogged" tube would then procede to follow the path of least resistance. This path wouldn't be up through the air filter, it would be out the stock hose. The only air entering the engine would therefore be the air it sucked up.

Second, about the air being colder. So I started thinking, if the air isn't being forced in, perhaps "fogging" simply allows the engine to suck colder air than the air coming from in front of the grill. Colder air is more dense, so an equal ammount of colder air would be equivelent to much more warm air. Everyone seems to agree that the air down low would be colder than the air at grill level. Why? I drive on roads that are typically black or grey. The pavement gets hot in the sun, and the closer you are to it the hotter the air is. Thus I have no reason to believe the air closer to the pavement would be any cooler.

My final thought was that perhaps just having a second source of air to the airbox would allow the reported increased air flow. I checked out the article in the notebook section about adding a dual air intake. The author did seem to think that this gave him more power because of the added noise, but when he tested it he found out that it didn't change. So that is ruled out.

Has anyone besides the inventor tried measuring the air flow after fogging? Has anyone checked their HP?

Once again, I am no engineer. If my reasoning is faulted in any way, please let me know. This is driving me nuts.

[jflip2002]

As for the temperature of the airs, I think you're off. You're not sucking air directly off the hot pavement. It is infact traveling, and cooling down. And no matter how hot the groud is, its not as hot as an engine.

As for the dorced air, just leaving out of the original intake port, I think that's a very valid point. That does seem very logical.

Maybe if you look at it rather than air being "forced" in, but just more air being "allowed" in, it would make more sense. The original fogging said put the hose by the fog lights, not in the brake ducts. The brake ducts just seem to scoop up more air.

But then again, I'm not an expert either

[myblueTI]

the engine sucks in air first off. So by allowing the car to get more air into the tube it allows the car to suck in more air and it happens to be cooler

[maherbaz]

Back to this colder air thing......is it really possible for the air by the brake duct to be colder than the air entering through the grill? The closer you are to the pavement, the hotter the air is. Makes sense, right? So I would guess the air at grill height would be just as cold, if not colder.

OK, so the benefit is coming only from having a larger tube, or multiple tubes, to allow air to be sucked through? Well if this is the case, then why bother with the fog light or brake duct, why not just another snorkle to the other side of the grill?
But as it has already been established, this secondary intake has no effect besides sound (from the article in the notebook section).

So I still cannot figure out where this extra performance is coming from.....anyone else?

[aceyx]

Originally Posted by jflip2002

As for the temperature of the airs, I think you're off. You're not sucking air directly off the hot pavement. It is infact traveling, and cooling down.

the air is "sitting" there until you drive by and scoop it up. in traffic and with wind, the factors and resulting case changes.

[jflip2002]

After this debating, I said to hell with it, and I fogged my airbox real quick lastnight. I just put some defroster hose, like what older vehicles use, by my foglights. The defrosteer hose is black, so it doesn't look as tacky ass the silver.

Its a huge difference in power. My car accelerates way faster. And as for the snorkel, I'd like to see you fit one by the grille. And if you do, it will look tacky. My noise of my intake didn't change too much, its a little more throaty. The benefit appears to be in the acceleration. Try it yourself, then talk about it bot working I guess. If it doesn't work to your standards, then you can rivet a piece of plastic, along with some gasket maker, in place to plug it

[schussey]

just do it.

-chris

[robcarync]

like someone said...the original fogged airbox article just had a hose running down to the area behind the foglight, and only used one hose.

the stock snorkel/baffle had a hole about an 1.5 inches diamater that lead into the airbox..the fogged airbox has an intake diameter of 4 inches...basically the engine just has more air readily available to suck in...one big pipe is better than two small pipes is all i can really say....