dr-rjp

iTrader: (4)

I have a question, and an observation:

First, the observation. I took a look at my air filter (K&N) today to see if it needed to be cleaned. Well, as it turns out, it did not need cleaning, but the back half of it was clean while the front half was somewhat soiled.

Is this surprising?

Not really when you consider that the intake air is channeled to the front side by the curved bottom of the intake box. The box is curved to fit the wheel well..which has always puzzled me as to why the designers could not find a better place for it.

Speaking of the bottom half of the box, ever wonder why it has those ripples? Are they designed to create turbulence, or are they there to reinforce the box?

Which leads me to my main question:

Why is the front of the air scoop pinched off at the middle? Is that to increase structural strength, OR to create a better air flow? Seems to me that it creates an obstruction instead.

Thoughts?

99grnmaxgxe

iTrader: (11)

I think it serves as a column to give so it does not get crushed easily.

BlackMaxdout

Thats a very analytical approach to the way the maxima air intake is designed. One could only really give good answers by testing something like this on a flow bench...and doing minor modifications to see if anything would result from them. The ripples in the air box, I believe is for structure, but when you go back and look at them again, they are quite large, and if you've done the airbox hack, you realize that the plastic is thick and quite hard to get through. It's only an airbox though...how much strength do you need??? I'm quite positive that a fair amount of engineering went into the intake system. Look at the resonator chambers, and how they are set up, and the use of that black square behind the MAF that supports the IACV. Alot of people question why so many engine control features were incorporated, for instance, why there are 2 crank position sensors...one on each end of the block? In my experience, there are few family sedans that rival the Maxima for it's amount of engine control features.
On a side note...my lower airbox was completely covered in black sludge from over the years. It was terrible.

Mizter6

hey yea i notice the same thing with my air filter only one side is black while the other side was clean. but due to my lack to detail i dont know which side had the dirty part. was it the shallow side or the deeper side? anyone remeber. cuz if u also think about it wouldnt that mean u can lengthen the filters by turning it around

NmexMAX

iTrader: (22)

My A33B fitler has different 'soiling' patterns according to if and when I use GAB/PAB as well as different set-ups.

DR-Max

iTrader: (3)

Seems like you're thinking is more advanced than us concerning the subject. Let us know what you find out.

dr-rjp

iTrader: (4)

Thanks. y'know, I have never actually SEEN what the resonator looks like, either its outside or its inside. Does anyone have a photo of it?

What is the real purpose of the resonator? It cannot be for noise reduction because blocking off the opening to the scoop actually causes the noise output to be lower.

Closing it off does seems to produce another effect -- the BUTT DYNO senses a shift of power from the low end to the high end.

Does anyone have any definitive data (or photos) about the resonator?

dr-rjp

iTrader: (4)

In my post, I mentioned that the end closest to the engine (and to the throttle body) was the dirty part. After looking at my air filter, I simply turned it around so that the clean end was now closest to the engine before putting it back in the box.

95bluse

iTrader: (1)

^+1 I always do that after cleaning the filter. The dirtiest part is closest to the inlet of the intake, because the incoming air takes the shortest route. Wonder what the effect will be to just punch holes on the opposite end of the box when making the GAB? Seems like this would make more efficient use of the surface of the filter.

dr-rjp

iTrader: (4)

Unfortunately, you would be letting in hot air and also losing the incoming cool air. As you correctly noted, air, being a fluid, takes the path of least resistance, and that would now be any holes you punch into the box.

What I was wondering about is putting in a perfectly smooth and aerodynamic surface inside the box that would do a better job of channeling the air into the intake.

I envision a silicone coating on the surface.

95bluse

iTrader: (1)

How about using something like this to replace (or fit into) the bottom of the airbox? There might even be an ABS one available somewhere...
http://www.homedepot.com/prel80/HDUS...4+3573&pos=n05
Also, I was one of the early adopters of intake tweaks:

- Cone filter w/resonator
- custom midpipe w/o resonator wit cone filter
- removed intake duct

Got mad when I couldn't outrun a grandpa in his V6 Camry in the all-important stoplight-green-gonna-cut-you-off battle . So I chucked it all..went back to stock in search of low-end torque. I currently have a K/N panel filter & removed the little L-shaped piping that goes to the box under the battery. Seems pretty good, there's a slight drone at highway speeds, but that's drowned out by wind noise

BlackMaxdout

now you are just splitting hairs man. Coating your home-built airbox in silicone isn't going to do anything. If you set up a pitot tube test of the incoming air, you'd see no difference. I can guarantee it. The best NA setup is the stock airbox the way it is, with a minimally restrictive filter and cold air.

The best setup for power is forced induction. Enough said.

dr-rjp

iTrader: (4)

First of all, I was not talking about coating my box with silicone -- I was talking about placing a molded insert into the bottom of the box over the multitude of ripples that exist now. This molded insert would be perfectly smooth and coated with silicone (or something equally low in friction).

OK?

NOW, I have the data to show that the stock setup DOES NOT let in the highest velocity of cool air possible.

Check it out (I'll have photos and/or video to show later tonight).

I did a test to see what difference having the resonator tube in place (versus removing it) has on the velocity of air reaching the intake.

I placed a digital anemometer in line with the air flow inside the bottom of the box. I had three test situations:

1. Resonator in place (stock setup).

2. Resonator removed w/ scoop connection left open.

3. Resonator removed w/ scoop connection closed off (with a plastic aerosol cap.)

I placed a hair drier at the opening of the scoop, and turned it on high using the no-heat setting. I placed the anemometer about 3 inches from the box outlet and took reading for 30 seconds for each of the three tests.

The anemometer records peak velocity, so I only needed to take measurements long enough until the maximum is reached.

Here are the results:

1. Resonator in place (stock setup). 3.6mph

2. Resonator removed w/ scoop connection left open. 1.7mph

3. Resonator removed w/ scoop connection closed off (with a plastic aerosol cap. 9mph

Truly amazing.

Now, if the stock setup is so great, then why was there a need for such a restrictive resonator.

Why?

99grnmaxgxe

iTrader: (11)

Are you talking about the resonator in the midpipe or under the battery?

Pieps

What i did was remove the resonator, L pipe, and snorkel, along with the bottom half of the airbox. I have the filter ghetto rigged to the top half of the box with some tape and some aircraft wire. It flows a lot better, and sounds very beastly, and it seems more of a willingness to redline. Great setup

NmexMAX

iTrader: (22)

... ... ...

Tim96I30t

iTrader: (2)

Everything stock is too optimize fuel economy not performance. I am sure the engineers tested several intake designs and placements. As for the brace it is for strength as stated above. As for the resonator it reduces noise which most buyers like, a quiet car. Removing it can increase performance but it is louder, this has been discussed before. For best performance get a cold air intake, not the ram style ones.

Apparition

iTrader: (5)

I greatly anticipate further research DR RJP... but as far as people say that the stock intake is best well I used to think so as well, even for low-end power, but trust me go and get a PRCAI and come back... If you still believe the stock setup is best I would like to know your dealer and when I can start buying some product ;] I'm biased yea but I lived under the same impressions forever as well. What I did to conclude the effectiveness of the stock intake was to call Stillen and the guy I spoke with reply was the best system for an intake on any car is ram air (stock maxima type), but the maxima has a gazzillion different restrictions that make it not even close to as effective as ppl make it out to be. Now maybe with all the resonators and snorkus' removed but theres still that god awful airbox, anyways I concluded that I'd be getting the same performance perhaps a little bit better off the line with the PRCAI because Ram air isnt effective until you're moving as where the true CAI can pull cold air right from the fender without restriction.

Here's comes the banter and disreguard for ones conclusions

Apparition

iTrader: (5)

all I have to say is yes.

BlackMaxdout

do you still get the low end punch out of it? If so, then I'd go that route.

Apparition

iTrader: (5)

yea actually I was really afraid of loosing my favorite of all power, the "low-end punch" but its still there in all of its glory. Today thinking about that same question I made a run from a dead stop to 60 on a bridge and it hasnt changed, possibly gained a little as I stated before, but thats sound is def. worth the $100 I paid they're now $220 from Cattman. Someone claimed to have the dyno showing a little bit of an HP and TQ increase in the PRCAI, I hope they will re-surface.. Dyno's show the truth and nothing more, nothing less.

dr-rjp

iTrader: (4)

Under the battery.

dr-rjp

iTrader: (4)

I plugged the hole, and there was no increase in noise.

DR-Max

iTrader: (3)

A couple of forum veterans have done some experimentation with the intake resonator a long time ago. They tried removing the intake resonator and replaced it with an aftermarket mid-pipe + HAI and an aftermarket mid-pipe + hacked airbox. They hit the track and noticed the instantly louder exhaust and thought that their cars ran actually faster....placebic effect. Weeks later, then switched back to the stock resonator and hit the track again. They saw a big difference and concluded that the intake resonator is better. It was said that its design make it act as an air buffer which helps airflow and keep the engine from running out of breath at high speeds.

Another member actually did a dyno comparison between stock intake resonator w/ frankencar intake and frankencar midpipe + intake. The dyno reveals the truth. This is the thread that discusses this. Post #1 has a link to the dynograph.

Here's also a good read: http://www.isuzuperformance.com/isup...ch/intake.html.

With a little bit of research in the forum, you save more time re-inventing the wheel and actually discover some knowledge which have come from those who have already done the researching and testing.

dr-rjp

iTrader: (4)

Here we go again! You and I have gone over this well-beaten path, time and time again, and you still keep missing what I have been saying. As soon as you get any hint of a deviation from a stock setup, you automatically reject it out-of-hand. The references you provide are bacially an afterthought, and they prove nothing in relation to what I did.

OK, I am going to try it one more time.

I have said, repeatedly, from the very outset that I am interested in air flow velocities of the stock intake system versus modifications of same only to learn how air velocity is changed, if at all.

Am I stepping on any toes by doing this? No.

Am I committing heresy to the Car gods? No.

Do you care about the results? We already know that you don't. In fact, we already know what you are going to say before you even say it. We know you are going to belittle it regardless of what interest others show.

Do I care? Nah...

You see, I do not care about tests done with Frankencar, or Frankincense, or Frankenstein, or Frankfurter.

I have done my own research, and to date, nobody (with the exception of the R&R division at Nissan) has ever measured the actual air velocity as it enters into the stock air box from the stock intake before and after changes to the resonator setup.

Before you jump to your feet and scream, "That's not important," let me add that it is important to me (and to a few others on the board who have shown an interest in what I am doing). I do not need any justification for doing my research nor will criticism keep me from doing it.

You cannot say that what I did has been done before because it has not been done before. Even if it had, I would still do it. Research is validated by repetition, not dogma.

OK, that's for starters. If I had stopped with only measuring air velocity -- regardless of how pointless one might think it is -- then that alone would have been noteworthy. But, no. I decided to mess with the resonator tube, and that is when the purists went into convulsions.

By the way, have these same purists done any research -- real research -- on their own instead of parroting what someone else has done and showing how well they can Google?

Uh....no..

Now, listen. I like the stock system. I have always run with a stock system. Some of my best friends have stock systems.

But, for some unknown reason, as soon as I say anything that remotely sounds like I'm trying to prove a modded stock box is better than the pure, unadulterated version, WHAMMO!

Alarm bells ring and the Purist Police sick the dogs on me.

I have done one thing, and one thing only:

#1: Proven that the air velocity at the entrance to the stock air box from the stock intake will be affected by changes made to the resonator tube. It seems like a no-brainer, but given the results I got, it is far from it.

With the resonator in place (normal stock setup), air velocity was 3.6mph. With the resonator removed and the snorkel tube left open, air velocity dropped to 1.7mpg. With the snorkel tube plugged, air velocity jumped to 9mph.

That is a significant increase. What does it mean in terms of performance? Don't ask me! I only do the measurements and have no access (nor funds...nor desire) to put my car a dynomometer to give a quantitative answer. I could give you a butt dyno assessment, but you know how much purists hate that!

All the measurements show that the air velocity at the entrance to the air box of the stock intake is definitely affected by changes made to the resonator tube.

I have not said whether it is a good idea to remove the resonator tube and plug the hole in the snorkel. I did not even intimate such a conclusion. The reader can reach his or her own conclusion.

I never even said whether there is a relationship between air intake velocity and performance, but if you feel so inclined to step to the plate and tell everyone that no such relationship exists, do so.

You won't because you know there is one -- even if the practical effect turns out to be negligible in real-world driving.

Is 9mph "better" than 3.6mph? That is for others to find out.

I set out to test a theory, and I did so. I invite others to duplicate my tests if they wish to verify my results. Or, if they are on the side of the "leave-well-enough alone-it-ain't-broke" crowd, then don't do a thing.

Now, the next time someone says that they noticed a difference (no matter how slight) after removing the stock resonator elbow and plugging the snorkel hole, and some detractor cries, "But that's impossible," that person will now have some empirical data to support their claim.

It will not quiet the detractors however. No chance of that ever happening in my lifetime.

99grnmaxgxe

iTrader: (11)

AMEN BROTHER! When I have time I will remove the resonator under the battery (thanks for the detailed instructions), and see how it will affect sound, power, and fuel economy. I'll report back like a soldier!!!!

95bluse

iTrader: (1)

dr-rjp - nice detailed tests and I'm willing to plug the opening on my stock snorkle and try it out. I've removed the L pipe to the resonator under the battery, your tests shows that I'm losing quite a bit of ram effect air through this opening. This is quite logical as the air entering the scoop would rather exit the opening than "force" itself through the filter into the engine. I've put quotes around "force", since I'm ignoring suction on the intake cycles of the engine.

I wonder what your readings will be if you had the meter hooked up to a running engine? What effect does the engine suction have on the amount of air entering the airbox? Does modifying any parts before the airbox influence the readings of intake velocity on a running engine?

DR-Max

iTrader: (3)

We??? When??? I know I'm not going cenile but we never had this discussion. I know you have gadgets and too much time in your hands, just itchin to get into projects. No one is rejecting your research, its just funny how you tried doing this before when you tried to do your experimentation on engine compartment temps and the differences between when a car is standing still and when it is moving. Whatever happened to that? Yes, you did posted results but then the thread died after. Now you got something else to pick on.

I think you love to hear yourself talk or for this matter, you love to read what you wrote, because you love to write long drawn-out posts. I laugh at the fact that you have said those things like you actually know me as the kind of person that only rejects things. I just know when something is a waste of time. You remind me of a person that, instead of taking a direct route to work, you like to take the scenic route and just drive around in circles before getting to your destination. So far, what you are trying to accomplish had already been done in a more direct manner. You just like to add your little flowery words and phrases and sound like some professor in college.

If you cared to read that thread, its not about the frankencar, its about the intake resonator. What is the difference between having it and having an aftermarket midpipe. If you didn't care about that, then that's on you. Again, you are just trying to reinvent the wheel.

You should get yourself on that American Inventor TV show.

BTW... the removal of that L-shaped piping on the resonator by the bettery is not new. It's in the stickies...had you only been reading first. You did not come up with that.

I bet anyone in here that you will be posting a reply that is probably a half a thread-page long.

Apparition

iTrader: (5)

"There are few, if any, disadvantages to the mandrel bent pipe cold air intake systems."

- http://www.isuzuperformance.com/isup...ch/intake.html

(Ie.PRCAI as mentioned); so shutup with the stock intake system [arnold schwartzeneggar voice] haha


okay im done, please continue as planned...

BEJAY1

iTrader: (19)

Good link thanks. When it warms up a bit (and Zack ships me his resonator) I'll rerun some of my tests which I haven't done in 2 years. I'll be using my Auterra for intake air temp, and manometer for air pressure before the TB. I'll probably run 4600rpm tests in 2nd gear. Should be easy to test stock, PRCAI, res vs no res, and a different front grill for HAI as long as I get consistent weather.

dr-rjp

iTrader: (4)

I'm sorry, Dr-Max. I had you confused with Silvermax who was in on a three-way conversation with us, and we both were flaming him. That was way back on May 26, 2005 (RE: http://forums.maxima.org/newreply.ph...eply&p=4015653)

That was also the same post where I introduced the temperature readings inside and outside of the car (to support your contention that there's lots of hot air inside the engine bay waiting to get into short CAI or HAI). It was a three-page post, so it just ran its course.

You and I have always been on the same page. It was Silvermax that came across as Mr. Know-it-All.

In that interchange I stated:

You responded:

But then you had a change of heart:

Which explains why you did, in fact, criticize me earlier in this post, a la Silvermax.

BTW, May 26th was also when I did my temperature experiment, and that was a 3-page post running simultaneously to this one...and the thread "died out" when the other thread took precedence.

Two things need to be noted from my May 26th post:

#1: I did, in fact, follow the sticky.

#2: I was not trying to reinvent the wheel. Just answer questions.

For example, you did not know if the air from the fan would blow into the open resonator tube, but you decided to block off the opening anyway to prevent hot air from entering.

My first experiment, the temperature one, showed exactly how hot is the air under the hood versus the outside air -- thereby discouraging the use of under-the-hood HAI's and CAIs.

The second experiment confirmed your assumption that the intake air has a straight shot to the air box instead of being rerouted to the resonator baffle. If I were to do the experiment again, but have the resonator elbow facing the fan, I could also answer the question you had about whether the fan blows air into it.

At any rate, I do take issue with comments like "A couple of forum veterans have done some experimentation with the intake resonator a long time ago." and "With a little bit of research in the forum, you save more time re-inventing the wheel and actually discover some knowledge which have come from those who have already done the researching and testing."

Those are slaps in the face, pure and simple, and having a condescending attitude does not endear yourself to anyone on this board, be they newbie, or "veteran."

Remember, how you say things can be just as important as what you say.

dr-rjp

iTrader: (4)

From the Isuzu Performance article cited above:

"However, there are several disadvantages to the OEM intake system. The resonator and the plastic duct work can be very restrictive to air flow. These pieces are designed to reduce intake sound, and performance is not the greatest concern. removing the resonator and enough of the duct work such that the system still pulls in air from behind the bumper or fender can do a great deal to improve air flow."

OK. Which part of "removing the resonator ...can do a great deal to improve air flow" was NOT clear???

They said it. I believe it. I confirmed it. The defense rests.

Oh...and if anyone else is thinking about removing the resonator elbow and plugging the hole in the snorkel, be sure to reset your ECU as well.

Mizter6

how do u reset the ecu? and should u leave the resonator hole open? plus i didnt find the engine any louder what kinda cheap sound reducing crap is that?

99grnmaxgxe

iTrader: (11)

It should not sound that much louder, and plug up the hole with something.

dr-rjp

iTrader: (4)

To reset the ECU: Disconnect your battery, and reconnect if after about 10-15 minutes

Plug the hole with the cover from a spray can -- with the top of the cover facing the hole. You will need a smaller-than-average cover. Make sure that the top of the cover does not go too far into the snorkel tube and block off the air.

Wrap both the cover and resonator connector with duct tape for a good seal.

You're right. The noise will not be louder, per se...but it does sound different.

I'd like to add that the mod has improved my acceleration, but I am not exactly happy with the way it sounds now. It is hard to describe the sound, but I'd say that it sort of reminds me of my garbage disposal when I first turn it on.

I've added a sound clip here: http://dr-rjp.com/modded.mp3

You be the judge!

95bluse

iTrader: (1)

I thought of a few more follies.

- The "resonator" under the battery will always have air in it. It is not ever empty. Why would air divert into this tank? It's closed! There's no place for it to go. Air would rush right past into the intake would it not?
Here's my theory, this box under the battery is not a resonator, but a reservoir. That's why there is no difference in sound when it's bypassed. I think it has to do with the way the way air is sucked into the engine. This causes a vacuum on the trailing end of the air, very similar to way hot air is exhausted from the engine. I will try to find out more on this, meanwhile I'm hooking up the my elbow back to this resonator aka reservoir. This effectively brings me back to stock except for my K&N filter.

I wonder how a PR CAI would work if it had an opening to connect to this "resonator"? would be the best of both worlds...smooth airflow for top end & reservoir for bottom end...

Fr33way™

iTrader: (23)

That is a unique sound. It may be the quality but it sounds thrashy.

dr-rjp

iTrader: (4)

I had the microphone sensitivity set on Low (on my digital voice recorder), so that may have something to do with it, but "thrashy" is a pretty good descriptor.

Where's the best place in the cabin to put the recorder's mike, if you want to capture the sound accurately, and as the driver would hear it?

I had mine attached to the steering column, facing towards the engine.

dr-rjp

iTrader: (4)

Does anyone recognize what I used to plug up the hole in the snorkel here?



It's an alternative to using a spray can top, and you could probably reattach your resonator elbow to hold it in place.

dr-rjp

iTrader: (4)

A PADDLEBALL!

BTW, I finally took my car on a long enough trip to check my highway mileage. Averaging 61 MPH with the AC running all the time, I averaged 31.5 mpg.

The best I had ever gotten before that was around 28mpg.

I'm pretty sure that the air mod helped raise my mpg.