dholly,

In theory you are right (or at least I agree with you) in saying that if the A/F does not change in before and after pulls, then the ECU has little to adjust, in which case the ECU "learning" in theory should not yield any more results. But, there is the question of timings. I do not think the ECU will advance timings now that it detects a better flow (I am in the process of experimenting to see if this very thing is in fact possible - can we advance timings with a higher exhaust gas velocity?), UNLESS the timings were regressed by the ECU from it's "normal" position (-15deg BTDC on the Z's - still trying to figure it out for our cars) for whatever reason (bad "Cali" gas, driving style, etc.). One point that I HUGELY disagree with you on is calling +/- 0.5 A/F units to be within the "ballpark" . This couldn't be farther from the truth. The interplay of the timings and the A/F ratios is very sensitive to HP made. A 0.2 shift will decrease the HP made, albeit not noticeable. If you lean the mixture from 12.5 to 13.1 with aggressive timings, as in the TS ECU upgrade, this will cost you a lot of power and cause predetonation (like it did on my car).

The best thing to do is get the dyno after the ECU has relearned - our cars a funny this way. But if they are going to do dyno before anyways, might as well do the after dyno after your install if they are not charging you extra and since the car is on the machine. But I am concerned that braking in the Exhasut may actually yield more power (who knows). To be fair, a dyno 2 weeks after the install would be best.

Gurgen

<P ID="edit"><FONT class="small"><EM>Edited by gurgenpb on 12/27/03 09:00 AM.</EM></FONT></P>

 

OK, thanks guys, this is helpful info particularly regarding the timing issue. I thought minor timing changes were being made by the stock ECU to keep the 6mt at the optimum 12.5 a/f. The + or - 0.5 was straight from a Nissan tech, but it did seem to make sense to me because that's the (approx) change with the TS reflash for 5at (12.5 to 13.1). Based on your first-hand experience, I'll tighten that range to 0.20 - 0.25 if I proceed. I really was hoping to get two birds with one stone as the dyno is 2+ hr round trip.

So, it was the combination of exhaust and Street Edge TC that was too much at 13.1? That appears to be the common thread between your cars. Again, if I add exhaust only to a 6mt with stock ECU, I find it hard to believe that I am likely to experience such drastic a/f and timing swings as your reflashed 5at's with serious intake and drivetrain mods. But you are probably right there is some re-learning benefit, and waiting awhile will certainly not hurt anything other than my wallet.

2004 | 6MTs | Diamond Graphite/Graphite
Upstate NY

 

No, the 5AT sedan is runnign 10.4 - that's why it is slow in stock form (to thebest of my knowledge).They up the mixture to 12.5 - that is the optimum!!! And advance timing (meaning take it further back from TDC - top dead center). The Z for example has got a closed-loop setting of 15 BTDC (before top dead center). THe Consult II can advance it to 17BTDC - which with stock A/F does not cause any pinging). The sooner the flame is ignited - the more power can potentially be made as maxium pressure (due to combustion inside the cylinder) is reached at a more optimum point! You have to find where the optimum timing is on these cars - and that's what the ECU does.

You have to keep the two separate - the timings are separate from A/F.

Also, my TC was slipping because of a too-high a stall speed. 2600 seems to be OK. When it is slipping, it is taxing the engine less, the engine does not think it is being worked under full load (as slipping imparts less-thatn-full load on the engine) and hence never reaches the full closed-loop mode/optimum A/F of 12.5. I got rid of this phenomenon my bringing the stall down to within spec (2600 max).

Gurgen

<P ID="edit"><FONT class="small"><EM>Edited by gurgenpb on 12/28/03 12:22 AM.</EM></FONT></P>

 

Based on my experience, do not underestimate the effect of the ECU when dealing with mods. It affects EVERYTHING. When I first installed the stillen exhaust, I was disappointed with the gains. I then did every reset procedure, and took it out for a spin. The engine did NOT know how to deal with my mods. Typhoon, Crawford, Stillen. The first time I punched it, the car just sat there and did nothing for about 3 seconds, then it took off like a wild thing and hit the rev limiter before it could shift itself. It was totally unprepared for the extra flow it now had over the stock A/F map settings. After thinking about this now, I should have eased into it a little bit before going full tilt after the reset.

In summary, it is my opinion that an ECU reset is vital to get the most from your mods. I took my Typhoon off and went back to stock since I can actually feel a torque improvement now. As Gurgen said, these engines are very sensitive and even slight changes to 1 system will cost you power. The Nissan Engineers have vastly more resources than Injen, or Crawford, or Stillen and they know what they are doing. If not careful, most guys will make their cars slower with these mods, and worst case, blow up their motors due to lean conditions. Be careful.

 

Well I had a couple free hours this am so I installed the exhaust myself with help from a friend. So much for my baseline dyno! But based on the discussion here I think it's for the best. I do want any dyno time to be as accurate as possible and money well spent.

I can say installation went without any big hitch. One step not mentioned in the instructions is to loosen the cat brackets. The front of the X-pipe was about 1/4" shy and I temporarily had visions of having to cut the front X-pipe cross brace and re-weld before loosening the cat brackets. But, really, even my friend commented how well this went together. The rear muffler tips aligned perfectly in the back bumper cutout the first time we cinched everything down tight. ZERO jiggering around and no cuss words were neccessary.

The sound at idle is little different from stock but, boy oh boy, she makes some noise as you bring the rpm's up. It really does have a nice deep tone to it, much closer to V8 than V6 now, IMO. Haven't had much time for an extensive test drive, but I will agree it is noticably louder in the cabin at 80mph and 3k rpm in 6th gear.

So far, I definitely like this thing. I'll go do an ECU reset tonight and see how if feels after. Then I have 7 days to dyno time, hopefully it will adjust sufficiently by then to really show what she's got. Gurgen, Dave and Karl - thanks again for your input.

2004 | 6MTs | Diamond Graphite/Graphite
Upstate NY

 

Congrats on the install

Drive the car through for a while. The exhaust will get a little quieter over the next 1.5-2 days. Aside from the sound, I firmly believe that the ECUs have to learn the new airflow charateristics - you may notice a difference in response over te next 1-2 weeks.

Gurgen

 

Dholly...

one other thing.. the weird smells (fuel, packing oil etc..) will also go away in about a week.

The sound will also change as the exhaust breaks in. I'm loving it now, but it took a few days to get used to it. No issues with the gains though. this puppy is truly exhaling big time and you'll get the giggles each time you stomp on it.

Cheers, Ted

'03 Sedan 5a: BS/G, Prem, Aero/Body, Sport, Nav
Click for MODS or Vote at Online Showoff

 

Thanks Ted. You know, I was completely taken by surprise at the difference in engine and exhaust sounds that doing the ECU resets made! Particularly the Idle Air Volume Learning (Throttle Position Learning). The engine smoothed out very nicely after the resets. It is noticably quieter, smoother and refined all along the rpm band. While I do think the trunk amplifies the sound somewhat, exhaust noise in the cabin at cruise has been positively affected as well, no longer as booming or resonant. I'll admit to being somewhat relieved about this, and to hear that it may actually get even quieter still as it breaks in, is icing on the cake IMO. I like maintaining that "stealthy" sedan profile. So far I agree this system is relatively unobtrusive under an easy right foot, but comes alive with a great, beasty V8 growl when you put the hammer down! People look!

Something I haven't seen mentioned yet is that, while the inlet side of the rear muffler obviously accomodates two seperate incoming pipes, the outlet side is actually a single outlet that dumps into a common area in the muffler body just in front of the twin tips. I had assumed the tips exited the muffler body directly. The tips also extend slightly further out and the muffler hangs just a tiny bit lower than stock. Also, the new tips appear to angle down slightly more than stock. I touched the Stillen tips lightly on a driveway that had never been a factor before.

My only nit picks would be: 1.) for the money, Stillen should include (2) new cat-to-Xpipe exhaust gaskets rather than forcing you to reuse the old ones, and; 2.) while entirely subjective, I think rolling the edge of the tips for a bit thicker straight on view and embossing the Stillen logo on top of each tip would have been a classy touch. But then, I'm still grinning!

2004 | 6MTs | Diamond Graphite/Graphite
Upstate NY

 

dholly (Registered)
12/29/03 11:31 AM

Something I haven't seen mentioned yet is that, while the inlet side of the rear muffler obviously accomodates two seperate incoming pipes, the outlet side is actually a single outlet that dumps into a common area in the muffler body just in front of the twin tips. I had assumed the tips exited the muffler body directly. The tips also extend slightly further out and the muffler hangs just a tiny bit lower than stock. Also, the new tips appear to angle down slightly more than stock. I touched the Stillen tips lightly on a driveway that had never been a factor before.
__________________________________________________ _

So if I understand you right your saying that the muffler is dual in, then merges inside the muffler body into one pipe, splitting again on exiting the muffler body into two tail pipes. Is that what your saying?

"i, for one, am not a fan of glory hounds."

Dang straight, it's all about the glory of helping. Who have you helped today?

 

Pretty much. Say you were looking at the muffler body from a side view, the tips are welded to the outer most rear wall of the muffler body. But, if you look into the tips, you notice each tip does not lead directly into a seperate outlet hole from the muffler body. Rather there is another "inside end wall" enclosing the muffler guts about an inch or two forward of the "outside end wall" where the tips are attached. There is only one single outlet opening from the muffler body thru the "inside end wall" into the space between the inside and outside end walls. This is clearly visable simply looking into the tips.

2004 | 6MTs | Diamond Graphite/Graphite
Upstate NY

 

I just took pics but can't resize them to post. If you can, pm me and I'll email them.

2004 | 6MTs | Diamond Graphite/Graphite
Upstate NY

 

Doug,

There's been lots of discussion about dual catback exhaust system design here and on my350Z.

As many of you know I was one of the guys who helped convince Stillen to build a catback exhaust system for our Sedans. Here's a little history from first hand information. There were at least five prototypes for the G35 Sedan. One of the first prototypes was "True Dual" with twin mufflers. Another prototype had essentially two mufflers in a common canister. (I posted pictures of that system mounted on G35 Sedan.) Both of these systems made great power but the sound level (dbs) and drone would drive you out of the car. The commercial version, including the muffler, is designed for an effective balance power and sound. I, for one, am very happy with my system's power, sound, looks and quality.



DaveO
2003 G35 Sedan - DP / Willow / AT / Premium / Sport
350Z Engine Cover, T-Stat & Air Duct / Stillen CAI
GG 7-Wire H-G Kit / TechnoSquare ECU
Street Edge TC / Stillen Exhaust System

 

so.... how would one obtain one of these prototypes? i for one, care nothing about drone. as long as there are gains, i could care less.

G35S 6MT
Technosquare ECU
350Z Springs & Struts
6-wire ground kit

 

Is there any way to make the Stillen Exhaust quieter?

 

Gotchaa, I don't know why you would say this if you haven't heard it yet. I hope you are not interpreting any of my comments to suggest I feel the sound, either in tone or db, is too harsh or loud. I don't. It's a performance exhaust for chriisakes! And, after spending a day in varying driving situations, the ONLY time I don't care for the sound is when the engine is laboring at very low rpms pulling in a top gear. Say, 6th gear and accelerating hard from 20-30mph. But, honestly, what business does one have doing that all too often anyways? Running thru the gears while shifting at a leisurely 3.5k-4k is louder, but by no means embarrasingly so. With a light foot I believe you CAN take all but the most conservative of clients. Run the gears to redline though and it is substantially louder 5k-6.5k rpm. Just the way it oughta be, IMO.

Dave, I have followed the R&D and production from the beginning, so I was somewhat surprised at the final muffler design. But I've said in the past I trusted Stillen to jumble all the variables and spit out the highest quality, best performance X-pipe exhaust for my daily driver, and I think they have succeeded. My car has a brand new set of ***** and my initial impressions remain highly favorable. In fairness, however, I'm holding back any final accolades until the ECU catches up and the dyno is done. Until then, like I said, I'm still grinning thank you very much!

2004 | 6MTs | Diamond Graphite/Graphite
Upstate NY