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Air box modification


A simple inexpensive way to get a better sound a tiny performance gain. In the Fabspeed cold air kit $225.00. For my modification visit home depot and get a 2 inch pvc joint, and 2 inch rubber cap. Remove the air box lid and remove the air muffler 3 screws. Take the pvc joint and from the center measure 1.5 inches and cut off the ends. place the rubber cap in one end and place the pipe through the hole of the air box lid, place the small hose on the intake hose to the pvc expose part with

 

Edited by blueline

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A simple inexpensive way to get a better sound a tiny performance gain. In the Fabspeed cold air kit $225.00. For my modification visit home depot and get a 2 inch pvc joint, and 2 inch rubber cap. Remove the air box lid and remove the air muffler 3 screws. Take the pvc joint and from the center measure 1.5 inches and cut off the ends. place the rubber cap in one end and place the pipe through the hole of the air box lid, place the small hose on the intake hose to the pvc expose part with the hose clamp and you are done.

I also performed this same modification last week with almost the same parts. I now have an even deeper sound out my PSE equipped car, and you even noytice it with the PSE on silent mode. Very happy with the result, the whole modification is straight forward and 100% reversible.

Nikos.

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A simple inexpensive way to get a better sound a tiny performance gain. In the Fabspeed cold air kit $225.00. For my modification visit home depot and get a 2 inch pvc joint, and 2 inch rubber cap. Remove the air box lid and remove the air muffler 3 screws. Take the pvc joint and from the center measure 1.5 inches and cut off the ends. place the rubber cap in one end and place the pipe through the hole of the air box lid, place the small hose on the intake hose to the pvc expose part with the hose clamp and you are done.

I also performed this same modification last week with almost the same parts. I now have an even deeper sound out my PSE equipped car, and you even noytice it with the PSE on silent mode. Very happy with the result, the whole modification is straight forward and 100% reversible.

Nikos.

Excellent i am glad it work for you.

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Can I do this mod with the stock air intake or this is only for fabspeed cold air intake kit?

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Any concerns with unmettered air flow into the engine?

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Any concerns with unmettered air flow into the engine?

Since you are only removing the air intake muffler and making the air filter box larger the small hose is blocked forcing all the air by the air flow sensor.

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Gotcha,

It looks similar to the one I did then. I used 1 1/2" pvc threaded nipple and cap. Painted the cap black and it looks like it "belongs", with the ridges almost lining up to the airbox ridges . Also, a 2" rubber gasket on the outside seals it perfectly.

post-4600-1192056767_thumb.jpg

post-4600-1192056794_thumb.jpg

post-4600-1192056814_thumb.jpg

post-4600-1192056841_thumb.jpg

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Gotcha,

It looks similar to the one I did then. I used 1 1/2" pvc threaded nipple and cap. Painted the cap black and it looks like it "belongs", with the ridges almost lining up to the airbox ridges . Also, a 2" rubber gasket on the outside seals it perfectly.

post-4600-1192056767_thumb.jpg

post-4600-1192056794_thumb.jpg

post-4600-1192056814_thumb.jpg

post-4600-1192056841_thumb.jpg

Call me stupid but I don't get it ? I had a look at this job today as I was cleaning my throttle body/butterfly. Is the idea to remove the air box muffler completely. Because my air intake which connects up between the MAF and throttle body, also has a bypass pipe that goes to this muffler box. Can I not just remove the muffler box put some kind fitting though the box lid then put a plastic cover over it slip over the bypass pipe and clamp up. Or am I mising the idea here ?

The picture shows a red connecting pipe with no bypass pipe. PS I have a 98 3.4.

......................Adam

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You are correct, the original intake tube has the two connections and the mod by Blueline works for that. I changed to a smooth nylon pipe from a cold air intake upgrade from Schnell. You can get it at

www.vertexauto.com

and they sell on Ebay as well, about $100.

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Really like BlueLine's Mod . . but was wondering about pilling air from around the PVC pipe since it is not sealed?? I like the idea of sealing with a rubber gasket and was wondering if anyone did Blueline's mod but with a gasket to seal the connection?

Edit: I have been thinking about this and you would need some form of a threaded coupling so you could compress the rubber gasket . .right ?

Cheers

Edited by ChuckLogan

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Gotcha,

It looks similar to the one I did then. I used 1 1/2" pvc threaded nipple and cap. Painted the cap black and it looks like it "belongs", with the ridges almost lining up to the airbox ridges . Also, a 2" rubber gasket on the outside seals it perfectly.

post-4600-1192056767_thumb.jpg

post-4600-1192056794_thumb.jpg

post-4600-1192056814_thumb.jpg

post-4600-1192056841_thumb.jpg

Call me stupid but I don't get it ? I had a look at this job today as I was cleaning my throttle body/butterfly. Is the idea to remove the air box muffler completely. Because my air intake which connects up between the MAF and throttle body, also has a bypass pipe that goes to this muffler box. Can I not just remove the muffler box put some kind fitting though the box lid then put a plastic cover over it slip over the bypass pipe and clamp up. Or am I mising the idea here ?

The picture shows a red connecting pipe with no bypass pipe. PS I have a 98 3.4.

......................Adam

Where did you get the red nylon tube from?

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I got carried away and machined up a plug on the lathe.

I'm not entirely happy with the results. There is now a resonant high frequency noise

that comes into the car are certain RPM. I read somewhere the latest 997 airboxes

have a movable flap inside to fix that.

intake-resonator-o-ring.jpg

intake-resonator-plugged.jpg

Bill

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I'm not entirely happy with the results. There is now a resonant high frequency noise

that comes into the car are certain RPM.

intake-resonator-plugged.jpg

Bill,

is that metal? Any chance it could be "ringing" at a high frequency from vibration in its seat?

Mark

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Bill,

is that metal? Any chance it could be "ringing" at a high frequency from vibration in its seat?

Mark

Mark,

It's Delrin. A type of plastic similar to nylon.

It doesn't sound to me like that's the source. And it's a snug fit in the hole

with that O-ring.

Given what I read about the 997, I suspect it's the same noise the factory decided to get rid of.

<<<

The air filter of the 3.8 litre engine differs from that of the 3.6 litre engine

through an active on-demand resonance reservoir integrated in the upper

part of the air filter.

Undesired noises can be insulated by adjusting the volume of the reservoir

according to engine speed, whereby sound in the passenger compartment is

optimised. One of the goals in adjusting the passenger compartment sound has

been to reduce background noise in the higher frequency range and to greater

emphasise the sporty, load-related exhaust and intake noises between 300 and

600 Hz. Opening and closing the resonance reservoir produces an

improvement in the intake noise of the 3.8 litre engine, particularly in

combination with the specific intake system of the 3.8 litre engine.

This reservoir is activated via a vacuum-controlled flap as a function of engine

speed and using temperature compensation. The flap opens in the temperature

range between 0 and 30 °C at between approx. 4,600 and 4,800 rpm and

closes at between approx. 6,000 and 6,250 rpm.

>>>

You can see the flap in the pic, inside the hole we've been plugging up.

997-air-cleaner-flap.jpg

Bill

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Looking to do this on my my2000 3.4

"place the small hose on the intake hose to the pvc expose part with the hose clamp and you are done."

This is the part I don't understand. Is the "rubber cap" really a coupler instead of a cap? If it's a cap, how do you connect the intake hose to it?

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Does anyone have a step by step pictures? I'm still lost.... I got the idea of blocking the smaller pipe and removing the air box muffler which is inside the air box so it can give more air capacity. Also by blocking the small pipe it delivers all the air through the main elbow pipe through the MAF... Am I getting this?

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I’m sorry but what/s the point of this? Does it give more power and or economy?

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Bill,

is that metal? Any chance it could be "ringing" at a high frequency from vibration in its seat?

Mark

Mark,

It's Delrin. A type of plastic similar to nylon.

It doesn't sound to me like that's the source. And it's a snug fit in the hole

with that O-ring.

Given what I read about the 997, I suspect it's the same noise the factory decided to get rid of.

<<<

The air filter of the 3.8 litre engine differs from that of the 3.6 litre engine

through an active on-demand resonance reservoir integrated in the upper

part of the air filter.

Undesired noises can be insulated by adjusting the volume of the reservoir

according to engine speed, whereby sound in the passenger compartment is

optimised. One of the goals in adjusting the passenger compartment sound has

been to reduce background noise in the higher frequency range and to greater

emphasise the sporty, load-related exhaust and intake noises between 300 and

600 Hz. Opening and closing the resonance reservoir produces an

improvement in the intake noise of the 3.8 litre engine, particularly in

combination with the specific intake system of the 3.8 litre engine.

This reservoir is activated via a vacuum-controlled flap as a function of engine

speed and using temperature compensation. The flap opens in the temperature

range between 0 and 30 °C at between approx. 4,600 and 4,800 rpm and

closes at between approx. 6,000 and 6,250 rpm.

>>>

You can see the flap in the pic, inside the hole we've been plugging up.

997-air-cleaner-flap.jpg

Bill

This is really smart! All the straight-pipe cold air intakes eliminate the Helmholtz resonators which compromises sound at resonant RPMs. I wonder if it'd be possible to retrofit the vacuum controlled 997 resonant chambers onto a 996.

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This is really smart! All the straight-pipe cold air intakes eliminate the Helmholtz resonators which compromises sound at resonant RPMs. I wonder if it'd be possible to retrofit the vacuum controlled 997 resonant chambers onto a 996.

I've thought about it, but never got around to looking at a 997 airbox in person.

I don't know anyone locally with a 997 and didn't want to just buy one for the research.

I also thought about a custom made throttle flap possibly using a RC servo.

The electronic control would have to be a separate standalone box as that aspect isn't

inside the 996 DME, but that's not difficult.

Bill

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I wonder if it'd be possible to retrofit the vacuum controlled 997 resonant chambers onto a 996.

Bill, if such a retrofit used vacuum lines and was designed properly, we wouldn't need a servo motor, correct? I'm wondering if it would be worth it to bring some calipers to the shop this Friday when I go to install my spoiler and flex disk. The owner has a few 997s for sale there, and he's nice enough to probably let me take some measurements.

PS - sweet ECU lab!

Edited by John Matthias Syrinek

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Bill, if such a retrofit used vacuum lines and was designed properly, we wouldn't need a servo motor, correct? I'm wondering if it would be worth it to bring some calipers to the shop this Friday when I go to install my spoiler and flex disk. The owner has a few 997s for sale there, and he's nice enough to probably let me take some measurements.

John,

There are various ways to pull this off. Somehow or another we'd need to convert electrical to motion.

You could use a spring loaded vacuum diaphragm, and a solenoid vacuum valve.

Just seemed to me to be easier to use a small servo.

If you're going to be around a 997 airbox, especially if it's off the car, I'd appreciate

a bunch of good pictures. Top and bottom, mountings, etc. to see how it compares

to the 996. Of course, be sure it actually has this flap in it.

Bill

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So  if you disconnect the small hose and seal off the hole in the box  and put the hose back you basically will accomplish the same thing?   I'm just looking for a little bit more throaty sound I'm satisfied with the horse power.

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