phenryiv1

iTrader: (19)

After the TB, what is the most restrictive section of the stock intake?

Pre-Airbox (including the "horn" intlake section)?
Airbox outlet? (doubt it)
MAF? (again- doubt it)
Resonator assembly?
Accordian section?

(Also, if this has been covered before, please be aware that my search function is all F'ed up, and only results in error messages in my browser...I am working on that!)

Bags

iTrader: (3)

I would say the resonator... It is there for sound deading from my understanding.

nadir_s

I'd like to know too... i'm guessin resonator too. I don't get how u have low-end power w/ the stock airbox... yet just a cone would reduce it. I just got my frankencar midpipe yesterday and i plan to put it on this weekend. I was thinking of using the stock accordian/flex section to connect the midpipe to the TB rather than using the rubber section it came w/ so i can adjust the intake properly for mounting. would using the stock accordian hinder airflow?

dashingMax

Atmospheric pressure
You are limited to 14.7 psi.
22 psi would be much much better...

Keven97SE

The intake snorkel (one that sits over the radiator to bring air from the front of the hood). I've removed that part alone and ran the stock intake and there were noticeable gains.

Besides that, the air box design is poor because the air is forced to turn 180 degrees from in to out. In the middle of that is the filter which does not flow air at angles. Additionally, the filter area is much smaller than, say a cone intake, so it offers a larger pressure drop and hence drops the flow. The stock intake box sucks.

But the worst thing is the snorkel. Really restrictive.

The resonator (between the MAF and throttle body) is not bad at all. Only a minor size step-down. The resonator chamber does little to impede flow.

phenryiv1

iTrader: (19)

I am very much inclined to agree with this assesment. First, the 180* idea is obviously true. Second, the area of the snorkel is OBVIOUSLY smaller than the area of the stock filter (though unrestricted by filtration devices), and the rectangilar opening it 1.5-2" by 3" at BEST.

In my Jeeping days, we would drill additional holes in the stock airbox (before the filter, obviously) to allow more air into the filter. By the SOTP, this was successful enough to make us happy until aftermarket suppliers created the equivalent of the midpipe w/ a K&N cone on the end, and later K&N created a true filtercharger system (FIPK) kit for the Cherokee.

What baffles me is this: The 190 HP, 210 ft.lb. 4.0L high-output I-6 in that vehicle made a LOT less noise with an intake than does the maxima. Why is our engine noise so LOUD w/ the resonators (or even the stock airbox) removed?

Even when I was up to an estimated 222 CHP and 250 ft.lb, I was quieter on the ENGINE side of the vehicle (though the exhaust was a LOT louder) than my maxima was w/ just the hybrid.

Back to the topic and reply, I looked at the stock resonator, and it has the same diameter as the midpipe that i had in there this week. Unless the air is forced or pulled around in the resonator, why/how would it create restriction? Air follows the path of least resistance, unless forced otherwise. So why would the air not just flow right on through to the TB?

njmaxseltd

iTrader: (19)

No air flows through the resonator box. (If thats what your refering to as the resonator) I don't think that slim box just before the MAF is indeed a resonator. I'm not sure what Nissan calls it. Our intakes have a sealed box attached to the intake piping. On 95 - 96 it was on top of the intake scoup. On 97 - 99 it's under the battery tray. Thats the resonator box that keeps the stock intake quiet.

The most restrictive part of our intake is the scoup. Open up the resonator box under the battery (on 97 - 99 models) and you have another source of cooler air to enter the intake when the car isn't moving. When your car is moving, the scoup should ram some air into the intake system. I removed that box, drilled a few large holes in the back of it right where it butts up against the inner fender well. There's cool air down there. Most of the piping on our intake is big enough to flow a good amount of air into the throttle body. The scoup is to narrow to allow that same amount of flow. Give another source of air intake to the stock piping and the car's stock intake breathes better.

phenryiv1

iTrader: (19)

Can you be a bit more descriptive? I am goin gto look for it after work, but any help is appreciated!

This is what I am talking about, a way to get more air IN without adding too much noise to the system. I LIKE my quiet ride. Did this modification add much sound to the setup? Did you feel any real difference?

Bags

iTrader: (3)

I was referring to the large plastic "box" near the battery... just as you stated.

phenryiv1

iTrader: (19)

See, I was thinking that people were referring to the plastic square between the TB and the MAF...WTH is THAT thing? And what does it DO?

Jamsan

iTrader: (2)

hm...i think im gonna tackle the resonator under the battery this weekend....

njmaxseltd

iTrader: (19)

Just follow the intake from the scoup back. It's the first branch off the piping you come to. Follow that branch to the Black Box.
Not really any added noise. If you listen closely you can just about make out a slight deep gurgle when you step on it hard from a stand still. Nothing at all like an aftermarket intake. Nobody would ever think you modified your intake. Did I get gains from it maybe a pony or two, it can breath better, definately no losses and best of all, it's a mod!

MAXIMARK

WARNING: this reply is by a new guy with lots of "ideas"...
I like the idea of stripping away the restrictive parts of the induction system. Someone on the General Questions Board wrote about flex piping to duct air up to the midpipe/K&N filter. I did something similar with my old car - a Volvo 240. Have you seen that the Frankenpipe Company has begun selling a shield (piece of aluminum) that is meant to reflect heat away from the K&N cone? I have been thinking of doing the flex pipe addition and fabricating a heat shield to keep the area where the filter sits in a cooler (forced air) environment. I believ that's what the Injun intake idea is - creating a cold box affect to deliver cooler air onto the TB. I would like to know if anyone has tested the engine compartment to determine heat ranges with different options? The other good idea would be to wrap the midpipe to "keep the heat off" and deliver cooler air into the TB. Many of Korean turbo diesel vehicles I use these days have a short scoop on the hood to route fresh air into the engine compartment.
Haven't completed any mods yet. I am currently on a remote tour in South Korea. Cheers, Mark V.

nadir_s

I've already got the heatshield planned out.... just gotta go to home depot to find the best material or whatever extras i can use to install it.

Also, spinning off the ghetto ram-air system... w/ the stock intake outta the way, there's plenty room to get a flexible heat insulated tube that i could use to run cold air from the bottom up to the filter... if i plan to do it, ill post pics. i doubt there will be any significant gains but i've wanted to do this mod since my first car (89 celica, couldn't do it cuz of extremly packed engine bay). Just for personal satisfaction i guess

dwapenyi

iTrader: (3)

It may have to do with positioning. The intake system on the Maxima sits right in front of the driver. I gather on the straight 6 Cherokee, the intake is quite a bit further away. I realized this when I converted from a CAI to the Hybrid. At WOT the CAI is still the loudest intake, but at steady cruising, the CAI was silent, but with the hybrid, I still heard something, I always hear something witht the hybrid. And as you know, the Hybrid setup, like most POPs, has the filter right there in front of the driver.

DW

96max5sp

So to gain more horsepower with the stock intake just remove the snorkel? anything else I need to do? I'm going to be waiting a while for the frankencar intake to come in.

StygianMax

iTrader: (8)

I thought I saw a wire leading to a sensor in that "snorkel" tube? If so & the tube is removed, what do we do with the sensor?

Dave B

IMO, the most restrictive part of the intake system is the airbox itself. Panel filters will never flow like a cone filter, especially a panel filter situated in a box with only a 2" X 3" opening. The intake scoop is restrictive in that it makes for a long path for which air has to flow, but it is cold air.

The box between the MAF and throttle body is a resonator. There is a change in intake noise when you add a midpipe. The sound gets deeper.

It is always wise to leave this scoop in place while running a POP has a way to funnel cold air.

BTW, the 95-96 has the same resonator setup as the 97-99, one resonator under the battery and one between the MAF and throttle body.


Dave

StygianMax

iTrader: (8)

Anyone ever think of putting a fan in the path of the snorkel somewhere? (I'm just thinking out loud.)

imported_2_tha_max

iTrader: (1)

OK... So you want to do something like in this website (http://www.acturbo.com/blowertesting.html). This guy says he put a fan in the intake of a el dorado and gain 21hp. Who wants to volunteer their make?

iregula

i would say resonator too

sryth

That's the boost sensor. I have a PRCAI, so I removed all of the stock plumbing. My boost sensor is zip tied to my battery cable, until I can make time build a bracket for it to mount to.

StygianMax

iTrader: (8)

Now THAT was good for a laugh!!! I guess that was the general idea I had in mind. But those hp/tq gains are a total "stretch"

I was initially thinking that anything to assist in bringing in cool air from the outside (short of installing a OSCAI/PRCAI) would help feed air that's more "oxygen rich" to the engine.

dko

iTrader: (7)

use the rubber connecting hose that came with the pipe, the accordion section won't keep the intake erect and the cone will hit your fender at every bump. it will also resonate against the fender and make unpleasant noises.

chris j vurnis

The resonator/accordian piece between the MAF and throttle body is very restrictive. Putting in a straight pipe there really improves the lower midrange from around 2500-4000 rpms. Would probably work well with a variable intake too for the top end.

The inlet to outlet of the resonator/accordian is not "line of sight". The air has to make a "zig zag" motion on some very sharp radius bends. One can tell how restrictive it is just by looking at it once its off the car.

Then of course the air filter box is really lame. A K&N or Amsoil foam filter would help a little bit. The foam might allow some degree of angled flow through the filter.

Nissan should have located the airfilter box about a foot behind the edge of the radiator rather than the far left side of the engine bay.
They could have used a box with a perpendicular angled panel (relative to MAF) with a "velocity funnel" leading into it (at the same vertical plane as the MAF) from under the battery tray and perhaps with another funnel like what is already at the top of the radiator.

Rather than going to the side of the engine bay and back to the front, they should have just gone straight to the front of the bay. They could have made it so much better and still kept it very quiet.

That's my two cents worth.

sterling99SEL

Has anyone checked out the K&N kits on ebay (cone filter and aluminum MAF adapter)? It doesn't look like anyone has bid on these under "Completed Items" so just wondering what you guys think:
http://cgi.ebay.com/ebaymotors/ws/eB...tem=1867635968

Also, there is a cheaper adapter and cone filter, but I'd rather have the K&N.
http://cgi.ebay.com/ebaymotors/ws/eB...tem=1867021526

Anachronism

Check the group deals section, that guy sells them cheaper to .org members. He has the same user name here as on e-bay (dohccivicna1250). I got the filter, MAF adapter and midpipe for around $100. Not sure what he gets for the filter and MAF adapter only on the org.

sterling99SEL

Thanks for the info, you might have saved me some $!
Here's the thread for anyone else interested...

http://forums.maxima.org/showthread....hreadid=124231

n2oMike

I was just going to remove the large black resonator box below the battery, and use a large hole saw to drill a large hole in the side of the front frame member to connect the resonator hose to.

The hole would have a header reducer (old car stuff, looks sort of conical) welded to the hole for the resonator pipe to attach to.

This way, the stock filter box could draw fresh air from both the factory scoop, and the foglight opening.

It's sort of a poor man's cold air inducton with a twist.

phenryiv1

iTrader: (19)

Nice idea. WHen you drill the hole, how large will it have to be?

imported_2_tha_max

iTrader: (1)

All right you caught my interest. Can you tell us more?

ericdwong

Has anybody actually dyno'd a b4 and after effect of with a midpipe (without resonator) and without a midpipe (with resonator) between the MAF and the TB? I still have the resonator in place, maybe this is costing me the 1-2 MPH that my car lacks at the strip compared to others on this forum.

n2oMike

You just remove the resonator under the battery box and use a hole saw to drill a hole in that front frame member directly across from the hose that goes to the resonator box.

You then weld a piece of piece of pipe to the hole to allow the hose to be connected. The pipe could be a piece of exhaust tubing the size of the hose.

The hole comes out right behind the fog light opening, so it's a nice source of fresh, cool air. (especially if you don't have fog lights)

If you take a good look at that area, you'll see what I mean.

I haven't done it yet, but as soon as the Warp Speed exhaust gets here, I'll get on it. (been a couple months so far)

Good Luck!

SE Maxima

my question is...what happens if you just remove the resonator from the stock setup? doesn't that leave you with an opening in the air flow path between the MAF and the TB? what is the likelihood of water/debris getting in there? and if you do remove the resonator, should you cover that opening with something?

Anachronism

You replace the resonator and accordian coupler with a smooth midpipe and couplers. Like this....

(Click for big pic)

SE Maxima

ahhh, i see. kind of a stupid question on my part now that i think about it.

today i actually cleaned my throttle body real well, as described on motorvate.com. it was amazingly dirty in there (my car has 100K miles on it). i also decided to leave the "horn" section of the intake off to see what would happen. can't say i feel any difference in power, but the car does seem to have a different sound to it at WOT.

also, since i did all this, my car is suddenly idling high...like 1800-2200 RPM instead of 800-1000 like before. any ideas?

Street Reeper

So the resinator under the battery on 95-96 is a closed box with no source of air? It is very easy to take out the curved pipe that leads from the resinator box under the battery to the intake snorkel that looks like a ram air scoup (I am trying to be very basic so anyone can understand this) I was worried about taking in warm air though, and wasn't sure if this box (underneath the battery)had an outside air source, or if it aided in flow characteristics of the snorkel. Also I drove a couple of times with that piece removed but because air flows from the least restrictive source I was guessing that this would bypass any cool air coming from the intake snorkel. I didn't notice any increase in noise so I was going to question again what the box underneath the battery is for, and if it has any source of air. I was just going to run some PVC from the outlet on the snorkel to straight underneath the car until my car is inspected at which time I will buy a PRCAI.
I looked through the intake box to the throttle body and it seems that the other resonator (the thin black box between the MAF and throttle body) would not cause restriction. Why is the box designed like this, what part on the intake is for noise reduction? I had first thought that the box underneath the battery might be there to collect any water that may come into the snorkel. I don't understand how that design would reduce noise, could someone help?