Here's a part that never gets any respect from the auto manuals. I cannot find any reference to it by name nor much in the way of explaining what it does.

It gets unceremoniously replaced by a short pipe with two tubes on an aftermarket intake -- which begs the question: "Why does this part have such an odd shape to it?" and "Is there a filter inside of it?

I'm assuming that it uses the vacuum created by the intake to draw off blow-by gasses, like a PCV valve, and route them back into the intake -- but if I'm wrong, you can blame it on the lack of info available.

So...please tell me, WTF is this thing?

Midpipe/Resonator/Oil Separator

my opinion is that it acts as some sort of oil catch can maybe for the valve cover and **** that hooks up to it, but i really don't know either...

Like Kev said, it has several functions. Most importantly, it's a resonator. I'm not going into the physics of it, but get rid of it and you're asking for a slight torque loss.

But alot of intake growl. Its been said that you lose a lil tq but you do get a meaner sound without it.

Why would you honestly want sound over power? But yeah, keep it.

You dont lose enough to notice. Plus i would rather have the sound . But thats me. i went turbo not to be faster but because i like the sound.

Did you not umderstand the post?

Not true. Depends on a few things. A few weeks ago I had a short ram and threw the stock midpipe back on and noticed absolutely zero sound difference. Drove my car today and it growled like a beast (with the stock midpipe).

To those arguing it isn't a noticeable difference, that's also false depending on a few things. Those with 5-speeds won't notice as much, but I have an auto and the difference in driveability is huge.

But a short ram without stock midpipe will be louder.

Put a cpu fan in it!

id rather not. Im boosted.

Twas a joke

I'd never consider putting that **** on my car

what year of max is that from ? my 97 looks a bit different

yeah but you dont drive on sounds

95-96? Mine looks like that.

Did you even read what I said? I'm guessing no, or you wouldn't have replied to it the way you did. I'll say it again, and maybe you'll get it this time: I had a short ram and put the stock midpipe back on and noticed NO SOUND DIFFERENCE. This was within a 5 minute period, so I don't think it was placebo, either.

I did the same exact thing a few months back.

I read wat you said. I also had a short ram before i did all the rest of my mods and it was a big difference. Maybe if varies from car to car. But i know on my 97
with the stock midpipe i had no sound. But once i went to the shirt ram it was loud as hell.

if you have a cai, take it out so it will look better but if your stock, just leave it, either way it will not make any difference i don't think, if anything it can help so oil and **** will not get into your intake and clog up ****

Right. Silent vs. waking the dead. I'll go with you on this one and ignore my own experience since you're clearly the sound expert. After all, you're the one with a turbo because you like the pretty noises it makes

I noticed that when I had the USIM, the tone was slightly different between the straight short ram midpipe and the stock midpipe. but overall, i thought that it was just about the same with respect to loudness. I found that the straight midpipe had a more raspy/annoying sound. with the 00vi, i think that the straight pipe pretty much sounds just like the oem midpipe with cone filter. at any rate, i'm trying to replace it with a 5th gen midpipe.

ok thanks

Good man

Dont you have a 00vi also? I know that will make a difference also. Im stillon usim.

I did notice a difference with the stock midpipeS and the straight tube. The Stock was always quieter and more refined sounding and I have had almost every intake combo minus Injen

Yes, I do have an 00VI, but I did the same thing when I had the USIM.

My comments the last day or two, yeah, I was in quite the bad mood. I still say I noticed no sound difference, but I apologize for the harshness

You cool man and im sure you know i didnt get the turbo for the noise either
But i think this will vary from car to car just like mufflers. On one car sounds completly different. I am actually still running my short ram midpipe in my turbo setup.

TVIS thought he was being so cute and clever about mentioning the fan mod, but I'm glad you brought it up because the difference between having it running and having it off may just have provided me with an answer to a problem that has puzzled just about everyone here.

Plus, when you hear what happened, you may have a better appreciation for the midpipes other functions.

About a year ago, I had a post called, "I love the smell of napalm in the morning," regarding the smell of raw gasoline that happened every time I started my car. It was most noticable in the morning.

I had someone start it for me so that I could check under the hood to see if the gas smell was eminating from there. It smelled more like it was coming from the exhaust. Checking the injectors and other fuel lines did not reveal any leaks.


People suggested everything from poorly pressurized gas cap to dirty plugs to a clogged PCV valve to a bad EVAP canister. I changed these but the smell continued to return. However, either I got used to it or the smell became less detectable.

OK. I start my experiments with the electric fan in the air box, and the one thing I noticed right off the bat was that having the fan on when starting the car caused the gas smell to be twice as bad as it ever was. Keeping the fan off reduced the smell to barely noticable.

Using a digital manometer, I had been measuring just how restrictive is our stock intakes. With one tube inserted into the top half of the airbox and the other end inserted into the mouth of the scoop, I measured a pressure drop of 3" H20 at idle (700RPM). This pressure drop increases to 9" H20 at 6k RPM.

BTW, this was done with no fan in the airbox.

With the fan in the bottom half of the airbox, I measured a slight pressure increase on the intake side of the filter (about 1.35" H20) at idle.

The fan does, indeed, create a restriction at higher speeds, so there's no dispute there. However, I routed an additional air intake to the airbox to compensate for it.

But, that's not what I ant to discuss. I want to talk about the gas smell and if the midpipe (and its connections) are the problem


We know that not much air flow is going through the TB at idle. So, is the extra air flow getting routed into the midpipe and causing excess gasses to be expelled?

I remember in one of my previous cars, there was a temperature activated choke on the air cleaner nozzle: when the outside air was cold in the winter, the chock would stay closed and gradually open as the engine warmed up. I presume that this had the effect
of making the intake mixture richer.

Don't know if there is a parallel here, but, with the fan off, the not only is the intake is choked off, but also the intakes (exhausts?) running from the midpipe.

So, what do you think is going on here with respect to the gas smell problem?

Thanks,

I got a fan but its not a cpu one.Mine runs of exhuast.

well said, beat me to it.