You are correct, it does make the car pull harder after 3500 rpms. As I said in the previous post, I drove around on highway last nite, with window down, it was loud when I had a couple of WOTs.

I guess it all comes down to how you evaluate the performance gain vs noise tolerance level with respect to your expectations.

Keep us posted, I am interested to see the outcome of these experiments as I am a new Stillen intake owner as well.

 

Yes there is a noise vs performance comparison made, but at the same time I'm still debating whether the loss down low is made up by the gains up top for my style of driving.

04 6MT Sedan - Z Tube, 04 Z Suspension

 

BrianV, others,

I am enjoying this post because I am contemplating buying the Z-Tube/Stillen Intake combo. I've been to two S.Florida meets and have yet to hear this setup. I am happy to see widely differing opinions but would like to see 'hard data'.

I am anxiously awaiting BrianV's "week later" results as well as any other dyno/quantitative data.


------------------------------------------------------------------------
When I die I want to go quietly in my sleep, like my grandmother. Not screaming in fear like the passengers in her car.

 

How about I make a video this weekend, back to back, at least it'll give an idea of the sound.

04 6MT Sedan - Z Tube, 04 Z Suspension

 

That's what I'm talking. A fat power curve is more important to me than a few extra ponies up top, as a 5HP increase up top isn't going to offset not being able to get off the line as quick.

Now, even if the headers and free-flow exhaust result in similar losses down low, the mean sound is a significant part of what I'm looking for. Of course, any well-designed set of headers and exhaust (intended for street use) will retain, at a minimum, the stock low-end while dramatically improving the top-end.

In this regard, I sure do miss the simplicity of a turbo's exhaust needs. lol Just open her up! lol


Future G35C Owner... ...Never too soon to think about modifications!!

 

I couldn't watch the insanity without commenting:

Brian V:
1) My "lame speculative replies" regarding automotive tuning come from owning a tuning business and doing it for a living.

2) You contradict yourself with the comment about it feeling much stronger up top, yet you are unable to 'bark' the tires at redline.

3) A guy in a minivan looked at you, so it must be a bad mod.

4) Your initial post INVITES flames "Flame me all you want"

5) You state that you will wait and see about the ECM reset, but your mind is already made up about the outcome. "I doubt it will"

6) We are supposed to wait a week for your reply, yet you reply to almost EVERY post. You even post your FINAL CONCLUSIONS in the very first post.

7) As far as "not whoring up the board," every other post on this thread is YOURS! Allowing people to comment on their (unscientific) experiences is useful.....arguing with every last comment is not.

You have already said that you don't track/dyno the car. If ultimate horsepower is not your goal, and this mod doesn't satisfy you TAKE IT OFF!!! Believe me, someone will buy it off you for a good price.

Not trying to flame, just my $.02

'04 G35X Graphite/graphite, NAV, wood, premium

 

Brian,

Dave B. here. I think your results are totally valid. While I don't have a G35, a former Maxima owner in our KCMaxima.org group has a G35 sedan auto. He's on this site and goes by the name "shortchaz". The day I saw the stock G35 intake tract I immediately thought there is absolutely NOTHING you can do to improve this setup. It's as ideal as you can get. The filter and intake opening are huge for an OEM setup and the piping is straight and not overly long and the intake sits right in the path of ambient air that comes from a high pressure area of the car. The OEM setup does incorporate a small intake resonator which probably does more good than bad. Well designed intake resonators not only muffle intake noise, they help equalize intake pulsations which ultimately helps volumetric effiency in the midrange and upper rpms. The 350Z probably doesn't utlilize the resonator because they wanted the Z to have a loud growl and they may have adjusted the VTC setup to help improve volumetric effiency. It's my understanding that the 350Z plenum is also slightly different than the G35s.

I too have had a multitude of intake setups on my Maxima and I've found the best overall setup is a true CAI utilizing the OEM intake resonator. This gives the VQ full low rpm punch, top end breathing ability, and ambient air. The reason I don't like the stock intake is because the intake tract is overly long and the opening is about 3/4" tall by 5" wide. Not exactly flow friendly. Without the resonator, the CAI setup feels a bit soft below 4000rpms and significantly louder above 4500rpms. Acceleration wise, I can't tell a difference. At the track there is a no measureable difference. The noise does give the impression of going faster though. I've have experimented with every single sort of intake setup available for the Maxima and the truth is they all perform the same at the track. The difference is driveability. Keeping the resonator and keeping a pressurized intake charge makes the car feel infinitely better around town. My CAI utilizes a 16" mandrel pipe and draws ambient air from the fender much the way the stock Maxima pulls air from the grille opening. Intakes that draw air from under the hood (POP style or "hot air intakes") typically kill throttle response. The Stillen setup for the G35 seems to emmulate these traits. I believe the throttle response and lack of lowend acceleration is caused by three factors:

1) An open cone with a relatively short intake tract causes the air to be more turbulent in the lower rpms. This causes the MAF to make numerous corrections in A/F and timing

2) The lack of a completely sealed off airbox causes a complete loss of the natural air pressurization formed in the airbox at speed

3) The hot air from the unsealed box is drawn into the intake where the MAF and air temp sensor read abnormally hot air and ultimately richen the fuel mixture and dial down the timing in an effort to reduce detonation.

When I get my G35, I'm changing nothing about the intake tract. It's perfect for NA performance. The only intake thing I'll change is the plenum.

BTW, shortchaz has an intake on his G35 auto and he didn't improve his ET at all. I believe in stock form he was getting 14.7s@96mph. With the intake he was getting 14.8s@96mph. The 60 foots were the same. No other changes.


Dave

96 Maxima SE
14.45@99.51mph with a 2.316 60'

JDM intake manifold, JWT ECU, Y-pipe, UDP, hacked stock airbox, 2K Maxima muffler

 

Hey Dave, good to hear from you; I know you're quite the intake expert. When you do get your G35 I'd like you to try the Z-tube, although you mention the resonator as a performance oriented functional product, I felt positive gains from the Z-tube and the sound isn't obtrusive at all.

I know you've been down the track 250+ times with several different combo's of intakes; thus, I look forward to you acquiring a G35 so I can hear your experiences.

Thanks!

04 6MT Sedan - Z Tube, 04 Z Suspension

 

Dave, I agree. Do an intake mod if you like the sound and like the looks. Don't do it for a performance increase.

I like the sound and I like the looks of the ztube with the popcharger, without the heat shield. As for performance, it still beats the hell out of my old '92 Civic Si.


2004 G35C 6MT Black. I stare. And I am content.

259737-2004_0518Image0001.JPG

 

DaveB,

Evidently your information is different than mine. After research, I found that the part number for the intake manifold collector (upper) or what is more commonly called a plenum is exactly the same for the G35 or the 350Z. The part number is 14010-CD000. Due to underhood clearances, the Crawford plenum has a small indentation toward the front of the plenum on a 350z where as the G35 does not.

Anthony

2003.5 Black 5AT Sedan
z-tube/ jwt popcharger/crawford plenum/crawford cats/
stillen exhaust/grounding kit/
technosquare ecu /350z thermostat/double din

 

ChicagoX, couldn't have said it better myself.

A couple of things I would like to add:

The open loop operation is what we are concerned with here. This means that the ECU will not be considering the lambda readings from the o2 sensor to determine how much fuel it should add per unit of air entering the engine; that would be closed-loop mode. Open loop mode is invoked that adds a given amount of fuel per unit of air entering passing through the MAF, regardless of O2 sensor inputs. The ECU resorts to this mode under a set of one or more specific circumstances: high engine speed (rpm), high load (throttle plate position), certain temperatures, etc... What's important is the following: there are 3 open-loop maps in our car, optimum, normal, and safe (to put it crudely) - in addition to other limp mode maps, etc; based on temperature, gas octane, etc, the ECU picks the map that is safe under those conditions when you stomp on the gas pedal. Over a long period of time, after "trying out" the different maps and making note of the knock sensor inputs (amount of detonation) and your driving style, the ECU modifies the variable for amount of "adjustment" to be made to any one of the 3 maps that it maybe using at any given time. This is mainly done by adjusting timing, hence adaptive timing feature of our cars - certainly a 2-edge sword for us power modders. The amount of adjustment (regression) that can be done is a finite value. The ECU upgrade sets this value to a much smaller, almost insignificant value so as to not decrese the power too much, while maintaining a certain margin of safety. For example, the timing is advanced for the sedan ECUs, tuning it for 91 octane (whereas the stock NORMAL map is set for 87 octane).

Now here is kicker. When you reset the ECU, and assuming you did a proper full reset (+ and - battery cables shorted for 10 secs - while disconnected from the battery, or a full 24 hour (not 12) disconnect), the learning, aka adaptive timing, aka regression, is erased, and you are right back to the most optimum map. Of course, once the conditions meet certain criteria (unknown to me), the ECU will switch to an appropriate map - this could happen in an instance or over time. However, in the meantime, immediately following the reset, the ECU expects a certain amount of air entering the MAF, @ certain loads/conditions, as it applies the correct amount of fuel. If you have a stock car, those conditions will certainly coincide "perfectly" (using the term loosely) with your mods, delivering a optimum A/F ratio with yet unadapted/non-regressed timing. This equals MAX POWER. But if you have mods that are not accurately measured by the MAF, as in downstream of the MAF, what you get right after the ECU reset might not result in ideal conditions; i.e. the ECU has adopted new map/timing that is not ideal for your new setup (mods), hence the need for a reprogrammed A/F map. The exact mechanism of this is not known, however it is fact that putting on a plenum (remember, it is downstream of the MAF) leans out the open-loop mixture from 12.8 to 13.5-13.8 at redline. High flow cats do a similar thing. To see proof of this, take a look at RugRat's post on 261.1 HP in this forum and look at the A/Fs before and after the TS ECU reset. The morals of the story (two of them anyway) is that (1) there is a narrow limit for learning in the open-loop maps, and (2) reseting the ECU works well for a near-stock car (in theory at least). I personally had mixed results with resetting, once it added about 5 hp, other times it made the car real slow.

Hope this helps...

Also,
BrianV... <blockquote><font class="small">In reply to:</font><hr>

On a similar note, people install FI kits on G35's and the ECU's seem to adjusts appropriately.

<hr></blockquote>
I would seriously refrain from saying things like this if I were you. That statement is beyond absurd, few of the reasons for which I addressed above. FI kits on stock G35 ECU's without any other mods is as suicidal as it is stupid. Statements like this will usually strip one of any credibility with people who know what they are talking about. Just a friendly advise.

Gurgen

<P ID="edit"><FONT class="small"><EM>Edited by gurgenpb on 05/21/04 12:38 AM.</EM></FONT></P>

 

I learned the hard way. Just leave the stock intake alone and drop in a K/N panel filter. Stillen, Injen, and the others cant hope to outsmart the Nissan engineering dept. The OEM intake is far from restrictive and actually is one of the best stock setups I have seen. Get a good catback true dual exhaust, put in a set of Irridiums or Bosch 4's, maybe a UR pulley set, and then have Tadashi custom map your ECU. In my experience, thats about as good as you will get without going down the FI path. She runs strong and mileage is good too, as I'm getting 24-25 avg. (80% highway) with a 5AT using 87 and calculating by actual filled volume. I was only getting 20-21 3 months ago and I drive the same route everyday.

 

gurgen,
Awesome post, thanks for the info.

karl,
Don't forget about the cats and the plenum. What benefit do you think the plugs would give, and why?

"Stillen, Injen, and the others cant hope to outsmart the Nissan engineering dept." What about the Nismo CAI? Wasn't that designed by Nissan engineering department? Not trying to be coy...serious rhetorical question.

2004.5 Coupe/5AT/Ivory/Everything but chin spoiler/Z Tube-Popcharger/Crawford V5 Plenum on the way

 

Karl is the plug improvement a function of the temperature on the gap itself? I would think keeping the tip cool would provide better detonation but how significant? Just like some who doubt you should play with the intake (i am becoming one of them - maybe..i will be swapping the injen to the stock to the Z tube this weekend and testing) I wonder if the ingition setup from the factory can be improved by changing the plugs. Would you suggest that there is a noticeable gain from irridiums alone?

2003.5 DP 5AT Sedan (E-thing but Nav)
14.2 @ 97.18
Injen CAI
10 Wire Hyper-Ground
Crawford Plenum (V4)
UR Crank Pulley
Polk ex-3500 Tweeter Upgrade/Shock Sensor/H-Liner Under Hood

 

Yeah Nismo is Nissan, but in reality their CAI only shows about a 3whp peak gain on a 350Z. That kind of gain is within Dynoject error.

Dave

96 Maxima SE
14.40@97mph, 2.20 60 foot. Best mph 99mph.

JDM intake manifold, JWT ECU, Y-pipe, CAI, 2K Maxima muffler