Many times in the tech forum I've read people advising to "knock out the inlet restrictor because all the air that gets to the engine goes through a hole the size of a screwdriver blade". I always found this a little hard to believe but, while working on the Finale, I had my airbox off and I'm never going to use it again so I decided to take a look at it.

If you look in the inlet, behind the little plastic screen on the side of the car, this is what you'll see.

Sure enough, at the bottom is the little slot. That must really restrict things. How can that provide all the air? It doesn't.

When you cut it open and see what's inside, it's clear how it works. This is what you'll see.

I drew the arrow to show the airflow. The air comes in and makes a 180 turn over the dam. As it does, the water is thrown outward (up) since it can't make the corner as fast as the air can. It hits the top of the water separator and runs either back out the inlet or on the back side of the dam and then out the little screwdriver sized hole.

The air never has to go through that little slot. What this means is that knocking the dam out will do little, if anything, for your airflow. Particularly with a stock engine. What it WILL do is increase the inlet noise since the turn also acts as a small muffler for it. The 6.2L diesels have a device on their intake that is strictly for muffling and works much the same way.

Morals to the story. Just because it's repeated over and over on the internet doesn't make it so and if something just doesn't seem right, it probably isn't.

John Stricker

quote Originally posted by jstricker: Morals to the story. Just because it's repeated over and over on the internet doesn't make it so and if something just doesn't seem right, it probably isn't. John Stricker

Well common since will tell you that the shortest distance is the fastest, and a 90 degree turn, another 180, and yet another 90 _will_ restrict airflow compaired to an straight through shot.

And since you made the compairison to mufflers the highest-flowing ones we sell (I'm a welder at a performance exaust shop) are straight through.

Rogue

Its been proven time and time again that knocking that out doesn't do diddly for ya car.. if anything it takes away.

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Ray - rturner@fierosite.com - Fierosite.com - Fiero Chat

Yup, theoretically...getting rid of the "kink" will lose you a little torque and gain you a little horsepower. Mind you, we're probably talking max one or two of either one.

Most people just like the swooshy sound the car makes...whatever. I've got an aftermarket intake on mine that makes the swooshy noise; lots of friends think it sound cool, but I could care less either way. It's actually kind of annoying if I'm trying to hone in on noises I think the car is making.

Thanks for the cutout picture...many people have explained it, but a picture does wonders for those without a good mental image!

Bryce
88 GT

I never said this was the best intake available. I use a ram tube myself in our car. My point was that it's commonly said here that the air going through this inlet all goes through that little screwdriver sized slot. That's not correct, in fact virtually none of it does.

You're right, ideally a nice, straight shot would be better. But how much better? If there's enough intake volume, the difference in removing the dam will be negligible, and I think many here have found out that fact for themselves.

I wouldn't try to let a 3800SC breathe through this, there won't be enough volume. A 4 cylinder? It might as well be not be there because that's all the restriction it will see. A 2.8 might gain a pony or two, but honestly I doubt it.

John Stricker

quote Originally posted by Rogue_Ant: Well common since will tell you that the shortest distance is the fastest, and a 90 degree turn, another 180, and yet another 90 _will_ restrict airflow compaired to an straight through shot. And since you made the compairison to mufflers the highest-flowing ones we sell (I'm a welder at a performance exaust shop) are straight through. Rogue

Dyno tests done by Herb Adams in the late 80's (or early 90's) showed absolutely NO difference between the factory air intake setup and a open element "hi performance" air cleaner. His conclusion was the Fiero intake system was very well designed and didn't need to be changed.

I've removed the air box on my Formula. The only change is more noise. If you like the sound of the intake, do it. But don't delude yourself into thinking it's a performance mod. That's the Honda guy in you talking.

That herb adams dyno test was done with a filter in the engine compartment.

Shaun Hamitt Dynoed his car with a custom tube intake and picked up 4hp and lost 8ft Lbs of TQ.

A few other people here have dynoed it , found HP and lost TQ

JM

whome ever said it gets sucked in by the screw driver sized slot is a dumbass. I didnt even cut mine in half you your can easily figure out how it flows, hence, i made this shortly after i took it out:

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--Adam--
1987 Blue GT 5-speed
IM AOL: GTFiero

my setup:

My quarter mi. speeds are higher with the open element and no water separator. However, I seem to have quicker 60ft with the stock setup and a drop in K&N. Guess it proves either 1)Gain HP, lose TQ, or 2) I'm an inconsistent driver, in either case, it makes a nice noise.

I knocked the water seperator out of my 87 GT once. I did it for the sound, not for any performance gains.

I didn't notice any difference in power either way, but what I did find was this.
Before I go too far, I'll add that the car had a Holley side scoop on it.

I had a heck of a time keeping air filters in it. They were always water damaged, lots of leaves, stones, sticks, cigarette butts ( thats where they went when I flicked them out...;p) even some bird feathers once.

My .02 cents is that a knocked out water seperator + holley side scoop makes for a very short air filter service life.

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jstricker, Thanks for the post you saved me having to take out the air inlet housing only to discover that the air does flow freely. Thanks again.

Anyone know how to get a throaty growl from our intakes at WOT?

quote Originally posted by FieroRacer: Anyone know how to get a throaty growl from our intakes at WOT?

SBC

LOL Archie..

but out of my 2.8, the intake is louder than the exhaust! heh.