Throttlebody position isn't that big of a deal assuming it's postioned so that the intake manifold gets the correct volume of air to each cylinder. The 3.0 VQ doesn't seem to have much problem with that.

The intake on G35/350Z uses the same kind of setup as the 4th/5th gen Maxima. Granted the G35/350Z design is slightly better, it's still the same concept. The G35 sedan employs a resonator between the throttlebody and MAF just like ours. The G35 coupe/350Z don't have this resonator and that's why their intakes sound deeper at WOT. Many G35 sedan owners have removed their resonators and all they noticed was slightly more noise and a slight drop in lowend torque.

Remember that just because the intake looks ugly and restrictive, it may not be the case. The intake on the WRX is a prime example. The WRX incorporates two resonators (one before the airbox, one between the TB and MAF) and an intake snorkel right above the radiator support just like our Maximas. Dyno after dyno has proven that the stock intake flows plenty of air to support 300hp. Just something to think about.


Dave

 

Dave B, have you compared?

CAI to a mid-pipe
CAI to hacked stock
CAI power drops off completely after 4 or 5rpm

 

Well, velocity would be what the CFM measurements would give us, no?

I didn't even consider resonance. Does the waveform of the air make all that much of a difference?

 

Underhood temperatures are not as hot as some of you think when the car is moving.

 

Yeah, you can figure velocity that way, but that's not my point.

Too large of an intake path an have the same bad results as too large of an exhaust. At low RPM, the velocity of the intake charge can get too low, minimizing the ram effect and cylinder filling. This hurts power.

Resonance if the intake system is critical. The most critical portion of the intake is between the plenum and the valves. To a lesser, extent, everything upstream of the plenum has an effect as well.

 

I recently tested the stock resonator over the midpipe. My drive back home from college is about 1.5 hours away, so I got to test both intakes well during the trip (back and forth) and definately know the feeling of the midpipe since I've had it on longer in recent times. Also, city temperatures were about the same during both drives.

I felt like I lost a bit of mid-end torque with the stock resonator, but felt a smoother response in the lower RPMs. But once the tach reaches past 3500, I feel like the midpipe does a better job at feeding the engine air. I honestly do...

I realized this when I downshift to gain some speed on the freeway. I'm very accustomed to the feeling of the midpipe...and while the stock resonator felt more refined and smoother, I don't think it was more powerful. With the midpipe, 5th gear acceleration at around 3200 rpms+ feels much more responsive compared to the stock resonator. Little tests here and there (all based on a butt dyno) such as slight tapping of the throttle, downshifting, 3.2krpm cruises w/ a quick punch, the midpipe proved to work better for me (and I didn't just base my opinion on sound).

But all in all, it's just another butt dyno, so there's no real proof, but IMHO I believe the midpipe will yield better performance overall (my original assumption) and I'm going to put it back on once I get my Y and exhaust installed.

 

Thanks for your opinion.

I've noticed the exact opposite. I felt more torque (especially in 1st), better tip-in acceleration, and stronger acceleration pretty much everywhere in the powerband. Oddly, the gas pedel feels stiffer in relation to input and I still liked the deep noise of the mid-pipe. I'll probably switch the two this afternoon and see if my opinion has changed.

It's just so freaking hot out here and my car just isn't liking it. Sunny 95-100 degree weather and 40%+ humidity (105+ heat induces) for the past two weeks has gotten REALLY old.


Dave

 

Try 116 degrees with 20% humidity, talking about oven hot!!! Everytime I drive my car out (and I drive my car for work as I am a field tech), I can only imagine how much hotter it is inside the engine bay, most likely hot enough to melt stuff. I'm definitely hating my leather interior...big time!!!

 

I was going to get a midpipe but after reading this thread I decided to do some research(the stuff nissan engineers probably did ) I came across these pages

http://www.users.bigpond.com/pgscott...resonator.html
http://www.users.bigpond.com/pgscott...rsAcoustic.htm

Basically the resonator is better for a certain rmp range....now I'm not sure if any of the hoses that go into the maxima resonator, uses engine speed/vacuum pressure to modify the resonace of the resonator for various rpm's.
I'm gonna do some more research and build my own custom free flowing variable resonator...hopefully before I'm old and grey

So for now the best thing I can see to do is replace the flex hose at the trottle body with a smooth hose...and for all we know the accordion style hose may have some purpose in resonance

Well I hope that puts the speculation to rest.

 

Wow, that's an excellent and imformative post!!!!!!!!!!

I had to be driving around for work earlier today so I reinstalled my mid-pipe. In a nutshell, the car simply felt weaker in gears 1, 2, and 3 at WOT and tip-in acceleration was worse. The word "soft" comes to mind. I've also realized I don't miss the loud wail of mid-pipe. With the hacked airbox and resonator the sound is still much louder than stock, but it's not a get-the-F-out-of-my-way sound. I guess I'll be changing back to the resonator tonight.


Dave

 

That material is fairly convincing.

 

I was also thinking that maybe the airbox also acts like the spring the resonance explanation and the hacked air box or even the air box with the snorkel would be better "tuned" for the engine. I know I get better gas mileage with my K&N cone than the paper filter in the box and I do like the sound but I was thinking that maybe a K&N for the stock air box could probably be better, considering both the resonance and underhood temperatures.

 

I doubt the accordian tube is much of a restriction either seeing that Ferrari uses the same kind of tube on their 600+hp 9000+rpm Enzo.

Maybe the reason the mid-pipe is so loud is because of the lack of resonance tuning and we're actually hearing reverberations. I know that you can feel the buzz of the engine at WOT far more with the mid-pipe.



Dave

 

what country is that licence plate from????

 

I totally understand how you feel with the heat lately since I'm in TX.

I never considered it before, but basically we're just trying to flow more air at the right rpms right? My Apexi SAFC II will read airflow, and I can even graph airflow versus RPM. I can't put my stock resonator in right now, but I can definitely change out intakes. Just something to consider since the SAFC will actually give you data instead of using butt dynos.
-hype

 

It's a replica German "Tourist" plate. You can get them from numerous places on the internet. Mine was $45 including the Euro plate frame.


xHypex-

Test out the resonator with the SAFC when you get a chance.



Dave

 

I have checked your homepage and that pic of hacked airbox shows hole in the side of the airbox- other than that everything is stock set-up(intake)???? i'm trying to test mine out and see what comes out of it.
plese post info on how to hack it and which stock parts are in use.

thanks

Nick

 

quote:

"So the custom intake is good for:


-looks
-noise
-see the engine better
-nice dress up part
But no performance gains "

just another product of false advertising to keep the market goin'

three days from now, you can find my Frankencar in the 4th gen for sale forum.


Nick.

 

I can't find my stock resonator box.. =( WAHHH!!!

 

I cut out the front portion of the lower airbox that is located directly behind the battery. I also cut the driver's side portion of the lower airbox and ran a 2.5" piece of shopvac hose from the opening to behind the headlight. I've got a K&N filter panel and everything else is stock.


Dave

 

Please do that for us!!

 

I would, but it's not all that easy for me because I have tons of wires and vacuum lines running for my nitrous and VI. I also removed the intake scoop, so the resonator can't rest on it like it used to. There's probably someone out there who has a SAFC who can swap in the resonator more easily.
-hype

 

Got my resonator back in.. Butt dyno says . Ear dyno says, . I say..

 

What about CAI? Would it work better than hacked stock at low rpm to mid rpm?

 

I'm not sure how I missed this thread and I'm sure as heck not going to read all 105 replies in it.

I had my JWT with stock resonator for a year and a half, I installed a midpipe this spring and didnt notice any performance difference. I don't know about you but the only way I can tell if a mod is working is usually to take it OFF. I'm not good at judging power increases, I can't feel them very well, but I do notice when my car is SLOWER than it was before. So given your theory I should have noticed that my car was slower than it was with the stock resonator, I didn't notice this. I don't believe that installing the intake midpipe did anything for performance positively or negatively.

 

I'm not sure how I missed this thread and I'm sure as heck not going to read all 105 replies in it.

I had my JWT with stock resonator for a year and a half, I installed a midpipe this spring and didnt notice any performance difference. I don't know about you but the only way I can tell if a mod is working is usually to take it OFF. I'm not good at judging power increases, I can't feel them very well, but I do notice when my car is SLOWER than it was before. So given your theory I should have noticed that my car was slower than it was with the stock resonator, I didn't notice this. I don't believe that installing the intake midpipe did anything for performance positively or negatively.

 

With the midpipe, I noticed better gas mileage.

 

The question at this point is: Does modifying the stock intake at all offer any gains? I wonder exactly what the engineers had in mind when developing our intake tract. Were they going for, as would be the case elsewhere in our car, a compromise between power and comfort (low noise level).

We've been discussing the midpipe, but the affects on resonance that the other aftermarket intakes produce have het to be considered. Once I fix my transmission, I'll have to do some testing.

I seem to remember a dyno test that showed that the y-pipe yeilds considerably less of an increase in power with the stock intake. I'll have to go searching for that info.

 

first - I don't miss that sound/whistle at all - VQ plus my Y-pipe and Focuz mufler saound great !!!!
power wise the car isn't sluggish no more !!!! especially in city traffic - will take it to expressway today....
and most important - my idle in gear with foot on the brake is soooo steady now !!!!! no more shaking and surging !!!!

i will hack the stock box and get creative with some PCV hose behind the headlight/grille to suck in some fresh air !!!!

midpipes



Nick

 

When I first put on my mid-pipe, I too didn't notice much difference in performance, but I did with the sound. The sound alone made me feel like I was definately going faster After years of running the mid-pipe I decided to swap on my resonator just as an experiment and I can definately tell the car "feels" stronger yet quieter. If you can get a hold of the your stock resonator, give it a shot for a day or two and let us know your opinions.


Dave

 

Excellent reference. The replacement of the resonator with the mid-pipe in the PR CAI may be the main reason that the HAI intakes perform better on the top end than the CAI. The JWT and Stillen use the stock resonator. Very interesting . . .

DW

 

I was just using the TB as a reference. It's the whole intake system, from the way the path is setup. In through the left side, resonance chambers below and above, then the air passing through the MAF and filter, another resonater, etc. And it all follows this curved path. It's clever engineering, but still a bit of a compromise.

DW

 

After looking inside the resinator it looks like the vaccum lines could could cause the air to swirl based on how the vaccum lines run and the design inside? Kind of like what the tornado claims without having any blockage of the intake path (I think this is what the article posted by Who that said "aiding volumetric efficiency" might have been talking about.) I have read that the concept of the tornado is useless on newer cars because the intake has already been tuned to do this, could that be the purpose of the resinator? However after looking at the 350z intake the resinator is missing, so I am battling back and fourth with this unless the intake manifold of the 350Z is better suited to not have this?

Also Dave, I have a sport compact car where they change the intake of a WRX and although it gave a gain in peak hp, in some RPM areas hp was way down (somehwere in the 30hp range.) They attributed this to the tuning that the stock intake system gave and said that the "big black box actually does serve a purpose." They had to get an air fuel controller to get positive speed gains from an aftermarket intake.

I sent a PM to emax and gave him a link to this thread since he is the one that DMB said had the dyno's of the franken vs stillen (midpipe vs resinator), hopefully he will chime in and give some info.

 

The links I posted had nothing to do with the tornado effect. It has to do with tuning compressions and rarefaction in the intake stream for maximum filling. Something like how a ram air intake works. There is still a resonator in the 350Z....its the air box and for all we know there could be other resonators incorporated else where in the intake that are not visible. I am now also begining to think that the VI for our cars works on the same principle.

 

i dunno about you guys, but I've had my stock resonator box with a JWT pop charger on my 96 for about 2 years already and I definitely noticed a loss. If you try to floor the car (if u're already at 30-40mph), it feels like the engine is trying wicked hard to accelerate and u feel a lag.

I had my Frankencar midpipe installed about a week ago and I noticed that my car responds alot better and it feels like the engine doesn't have to work to hard to accelerate (when u're already at 30-40mph and trying to accelerate faster)...

I don't get how the stock resonator and a JWT pop charger is a better setup than a midpipe + JWT pop charger. I'm not even sure what it feels like to drive with a whole entire 4th gen stock airbox anymore. Oh well, just my 2 cents!

 

Exactly and this leads me to say that every car is different. My car (auto) feels/is much more potent from start to finish. I drove with my stock box for years until I forked over the cash last year to get a full intake setup. My car is more responsive and pulls hard now that the ECU has adjusted itself to the intake.

 

I don't know about the "tornado" effect because the vacuum lines are only under vacuum at idle and part throttle. At WOT there is no vacuum. But there has to be something going on because the intake is significantly quieter at WOT with the resonator. For those that have looked inside the resontor, you'll notice that it's about 3" in diameter and has a small 3/4" X 1" internal opening leading inside the box area. This little opening must be responsible for the change in noise. How it works is beyond me though.

Everyone knows what the intake sounds like with a resonator (deep, snorty). For those that have the MEVI and a midpipe intake, the switchover sound is more audible the lower you set the switchover. If you set the switchover at 4000rpms it's loud. If you set it at 5300-5400 it's barely audible. Us MEVI owners have learned that the higher 5200-5400rpm setting is actually ideal in terms of all out acceleration. Since the MEVI is resonance tuned and the less loud the switchover the better, is it possible that the intake resonator is actually a resonance tuner therefore the intake noise goes down and the performance goes up? Just my BS theory.

As for the 350Z, it doesn't have a resonator. I know the G35 sedan has a resonator, but I don't know about the G35 coupe. I've scanned the G35 site and many G35 sedan owners have swapped to the 350Z non-resonated intake pipe and noticed no real difference in performance and a slight increase in intake noise. A couple auto G35 owners have noticed a slight lack in acceleration at certain points in the rpm band. One thing about the G35/350Z intake tract is that it has no vacuum lines going to it. Maybe the vacuum lines on the 4th gen intake do serve some sort of purpose?

The WRX intake is much like our intakes. It has a resonator before the airbox and one between the TB and MAF which includes vacuum lines. Like our setups, I think the resonator before the airbox is simply to quiet intake noise somewhat. Many WRX guys agree on this and end up yanking this resonator. It's the resonator between the MAF/TB that's the issue. When you remove it, there is a signiciant loss of power in the low to midrange (5-12hp) and a minimal gain of 1-2hp at 6500-7000rpms. The interesting thing here is that since the WRX is a turbo, resonators really aren't suppose to do much like they do on NA engines. The WRX kind of goes against that theory. Odd huh?

The heat in Kansas City has been relentless for the last 2+ weeks with temps soaring into the upper 90s/low 100s every day with 40-50% humidity (heat induces of around 105-115 degrees). What's amazing to me is that I can be at a 4500rpm roll in 2nd and go WOT and my VQ will slam me into my headrest and haul serious booty to 7000rpms. I switched to my midpipe last week and it didn't have near the snap nor the pull to 7000rpms. At lower rpms, the midpipe just seems to be flat.

I still have yet to dyno with my JWT ECU so maybe when I go I'll switch between the resonator and midpipe. Same goes for the track. Unfortunately I'll be out of town for the next two weeks so no racing or dyno time. Maybe when I get back the temps will have dropped back into the 80s. I've already run 14.4/14.5 @97mph in 85 degree weather with my MEVI/JWT ECU/midpipe combo so I have a baseline there.


Dave

 

Put it back on today, didn't really notice a difference as expected, I don't expect to feel a couple of hp. I will keep it on though for a couple of reasons, one the article about resinators that was posted, also the track times posted by a member that were better with the resinator, the fact that Stillen kept it on their intake because they do rigorous dyno testing for products, and the fact that the midpipe was not developed from dyno tests but rather an idea.

I would still like someone who has seen the Stillen vs Franken dyno's to comment and tell us what the curves looked like.

 

Man i wish i had my stock one so i could play around with it

 

Dave B i have a question. Last night I was out racing agents my boys 2002 Nissan maxima with intake and exhaust. We would go from a 2nd gear rol and every time my car would jump out a little, but in high rpms he would come back and get about half a car on me, and then threw 3-4-5th we sat dead even... Ive noticed this lately that I always seem to lose my races cuz of 2nd gear ... could this be an intake issue? I have the straight pipe from RMV and a cone filter from pepboys. if we went from 3rd and up we would sit dead even, or who ever pulled was because the other person messed up... let me know what u think

oh yeah PS we took them so high on the high way that my tack hit 140 but my RPMS keeped going! I asked my friend what his tack said when we hit the brakes, and he said 155 and i was still at 5 and a half grand on the rpm gauge... now one cant complain about this

Well, get back to me. Thanks

-Chris