MREV and Stillen 1st Gen installed
I have no theory knowledge of the exhaust principals but I am holding on installing Fuji. exhaust because I had similar AF experience after C. cats were installed. I will be looking for your new AF chart, thanks for sharing.
Joined: Jun 2005
Posts: 8,185
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From: Alabaster, Alabama
DaveB, I think you are disregarding the fact that the dyno in December showed the same "screwy" A/F problem as the one post MREV/Exhaust. When you look at it in those terms it seems pretty straight forward that the problem was at least partially there when the only "variable" was the cats. I know that Doug said the cats had no effect on the A/F that the ECU puts out and I don't doubt that he is quite experienced with the subject. I am however somewhat skeptical in that there are sensors in the cats. If those sensors didn't do anything then they wouldn't be there due to the cost involved in putting them in, etc. I still say that based on the full picture we have at this point the culprit is either the cats or a bad A/F reading from the dyno on mulitple occassions.
Former G35driver Vendor
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From: Los Angeles California
Originally Posted by trey's wife
the dyno in December showed the same "screwy" A/F problem as the one post MREV/Exhaust. When you look at it in those terms it seems pretty straight forward that the problem was at least partially there when the only "variable" was the cats.
This is the same thing I picked up on when looking at the data history. The problem started with the installation of the cats. This is not to necessarily say the problem is with the cats, but at a manimum it is related to the installation of them.
Could be a leak at the flange or a crack somewhere?
It would be very helpfull to know if the lean A/F condition was driven by one bank or both...
Originally Posted by trey's wife
I know that Doug said the cats had no effect on the A/F that the ECU puts out and I don't doubt that he is quite experienced with the subject. I am however somewhat skeptical in that there are sensors in the cats. If those sensors didn't do anything then they wouldn't be there due to the cost involved in putting them in, etc. I still say that based on the full picture we have at this point the culprit is either the cats or a bad A/F reading from the dyno on mulitple occassions.
So there are two problems to consider:
1) Why is it running lean?
2) What is the appropriate fix?
I don't know if you guys go to the Z board much, but some people are having problems with exhaust mods on the revup. (Test pipes or cats) It could very well be the variable exhaust valve timing requires very tight operational conditions. It "may" be a marginal design when exhaust mods are thrown on. ...Don't really know yet.
I will find out much more when I get many of my research exhaust mods on the dyno.
Hi Trey,
I scanned through some of the postings, but if I am repeating what someone else already posted...my appologies.
The biggest issue with your dyno runs is your AF, obviously: They dont pay me the big bucks for nothing!
D
But seriously, when we tune NA cars, we typically see the greatest trq and whp improvements across the ENTIRE power band, at right about 12.0:1 AF. Leaner mixtures, or richer mixtures result in less whp and trq.
You have an excellent foundation of mods, and with a tuning system, such as the EU or UTEC, I could easily add 15-20whp on top of this.
What many people forget, is that adding NA mods, in itself, does not result in the best performance gains. The engine must be tuned for those mods, or else your engine will run leaner, which results in less power. Contrary to popular belief, leaner mixtures do not always result in more power. Peak power theoretically is achieved at between 12.0:1 and 12.6:1 AF. Leaner or richer results in less power.
Hopefully that helps you out.
I scanned through some of the postings, but if I am repeating what someone else already posted...my appologies.
The biggest issue with your dyno runs is your AF, obviously: They dont pay me the big bucks for nothing!
D But seriously, when we tune NA cars, we typically see the greatest trq and whp improvements across the ENTIRE power band, at right about 12.0:1 AF. Leaner mixtures, or richer mixtures result in less whp and trq.
You have an excellent foundation of mods, and with a tuning system, such as the EU or UTEC, I could easily add 15-20whp on top of this.
What many people forget, is that adding NA mods, in itself, does not result in the best performance gains. The engine must be tuned for those mods, or else your engine will run leaner, which results in less power. Contrary to popular belief, leaner mixtures do not always result in more power. Peak power theoretically is achieved at between 12.0:1 and 12.6:1 AF. Leaner or richer results in less power.
Hopefully that helps you out.
Originally Posted by sharif@forged
Hi Trey,
I scanned through some of the postings, but if I am repeating what someone else already posted...my appologies.
The biggest issue with your dyno runs is your AF, obviously: They dont pay me the big bucks for nothing!D
But seriously, when we tune NA cars, we typically see the greatest trq and whp improvements across the ENTIRE power band, at right about 12.0:1 AF. Leaner mixtures, or richer mixtures result in less whp and trq.
You have an excellent foundation of mods, and with a tuning system, such as the EU or UTEC, I could easily add 15-20whp on top of this.
What many people forget, is that adding NA mods, in itself, does not result in the best performance gains. The engine must be tuned for those mods, or else your engine will run leaner, which results in less power. Contrary to popular belief, leaner mixtures do not always result in more power. Peak power theoretically is achieved at between 12.0:1 and 12.6:1 AF. Leaner or richer results in less power.
Hopefully that helps you out.
I scanned through some of the postings, but if I am repeating what someone else already posted...my appologies.
The biggest issue with your dyno runs is your AF, obviously: They dont pay me the big bucks for nothing!
D But seriously, when we tune NA cars, we typically see the greatest trq and whp improvements across the ENTIRE power band, at right about 12.0:1 AF. Leaner mixtures, or richer mixtures result in less whp and trq.
You have an excellent foundation of mods, and with a tuning system, such as the EU or UTEC, I could easily add 15-20whp on top of this.
What many people forget, is that adding NA mods, in itself, does not result in the best performance gains. The engine must be tuned for those mods, or else your engine will run leaner, which results in less power. Contrary to popular belief, leaner mixtures do not always result in more power. Peak power theoretically is achieved at between 12.0:1 and 12.6:1 AF. Leaner or richer results in less power.
Hopefully that helps you out.
Joined: Apr 2005
Posts: 3,521
Likes: 2
From: Birmingham AL
The mrev is an intake modification. Not sure how much you know about the g/z, but I'll go into details; if I go into too much detail, just ignore it.
After the air box containing the air filter is a plastic tube that connects to the throttle body. The throttle body itself is attached to the Intake Plenum. In stock form, the plenum is not visible as it's covered by the plastic engine cover. This plenum is made up of two parts: the upper plenum and the lower plenum. This plenum sits atop the actual intake manifold.
The upper plenum is simply a domed area with support stalks that let it rest above the lower plenum. The lower plenum has six individual intake runners that feed the intake manifold.
The 03/04 g's all had a single motor and shared the same plenum design. In 05, Nissan/Infiniti introduced what is commonly called the revUp motor(these are rated at 298hp versus 280), available with 6speeds in 05 and 06. The upper plenum remains the same, but the lower plenum on the revup features shorter runners. These shorter runners make more power in the upper rpms, but trade that for a loss of torque down low. The original lower plenum, still available in the 05/06 automatics, has longer runners but is not capable of the same peak hp numbers.
The mrev is a mod by a company named Motordyne Engineering (http://www.motordyneengineering.com). Incidentally, if you have any further questions, pm Tony aka Hydrazine, the *guy* at motordyne. Anyway, the mrev is a combination of an oem non-revup lower plenum plus an iso thermal plenum spacer. The lower plenum makes up for the loss of torque on the revup engines, and the plenum spacer allows for greater air volume to help retain most of the peak numbers of the revup.
The mrev gives great gains in the midrange, but loses power over stock after 6200 rpms. But the power over the entire rpm range is what counts.
If anyone else has anything to contribute, or correct, feel free.
After the air box containing the air filter is a plastic tube that connects to the throttle body. The throttle body itself is attached to the Intake Plenum. In stock form, the plenum is not visible as it's covered by the plastic engine cover. This plenum is made up of two parts: the upper plenum and the lower plenum. This plenum sits atop the actual intake manifold.
The upper plenum is simply a domed area with support stalks that let it rest above the lower plenum. The lower plenum has six individual intake runners that feed the intake manifold.
The 03/04 g's all had a single motor and shared the same plenum design. In 05, Nissan/Infiniti introduced what is commonly called the revUp motor(these are rated at 298hp versus 280), available with 6speeds in 05 and 06. The upper plenum remains the same, but the lower plenum on the revup features shorter runners. These shorter runners make more power in the upper rpms, but trade that for a loss of torque down low. The original lower plenum, still available in the 05/06 automatics, has longer runners but is not capable of the same peak hp numbers.
The mrev is a mod by a company named Motordyne Engineering (http://www.motordyneengineering.com). Incidentally, if you have any further questions, pm Tony aka Hydrazine, the *guy* at motordyne. Anyway, the mrev is a combination of an oem non-revup lower plenum plus an iso thermal plenum spacer. The lower plenum makes up for the loss of torque on the revup engines, and the plenum spacer allows for greater air volume to help retain most of the peak numbers of the revup.
The mrev gives great gains in the midrange, but loses power over stock after 6200 rpms. But the power over the entire rpm range is what counts.
If anyone else has anything to contribute, or correct, feel free.
Well, I can't post the results till I compile them with a friend. Once that is done I will post them. But I will say two things.
1) The Stillen CATBACK and Stillen CAI did make a nice gain of power on my 05.
2) Car was dyno tested today. And my A/F was perfect. Very similar to stock a/f.
1) The Stillen CATBACK and Stillen CAI did make a nice gain of power on my 05.
2) Car was dyno tested today. And my A/F was perfect. Very similar to stock a/f.
Here is the thread of my findings with the latest dyno as of today with the STILLEN EXHAUST and STILLEN CAI. The findings speak for themselves.
https://g35driver.com/forums/showthr...89#post1028189
https://g35driver.com/forums/showthr...89#post1028189
Joined: Apr 2005
Posts: 3,521
Likes: 2
From: Birmingham AL
Figured I'd post another update.
Saturday night Cheryl and I were driving our respective cars(with 1 passenger each) to a local restaraunt. I was taking a 135 degree turn onto an interstate entrance ramp. I was in first gear, with vdc off. I waited until I was completely straight, then slowly accelerated until I reached about 4k rpms. At that time, I jumped on the throttle.
I nailed me 1/2 shift, and my 2/3 shift (with my passenger having this o-**** look the entire time). At this point, I knew Cheryl was going to be behind me, and assumed she knew what I was going to do, so I figured she would try to keep up. So when I looked up in the mirror, she was on my tail; very very close. I had just thrashed my car down the entrance ramp, and she was less than a car length behind me.
When we got to the restaraunt, she made it even worse. She said she started in 2nd gear. So yet more proof that my car is running like a dog.
On another note, this past Friday and Saturday it was warm enough to actually drive with my windows down. I noticed that under load, the car is audibly pinging below 4500rpm, which is where I'm running so lean. This observation validates the dyno's measured a/f. So I could have been pinging for who knows how long.
It's time to get serious about this and get this crap resolved. I purchased some fuel injector cleaner over the weekend and I'm gonna give that a shot(almost 19k miles now).
Saturday night Cheryl and I were driving our respective cars(with 1 passenger each) to a local restaraunt. I was taking a 135 degree turn onto an interstate entrance ramp. I was in first gear, with vdc off. I waited until I was completely straight, then slowly accelerated until I reached about 4k rpms. At that time, I jumped on the throttle.
I nailed me 1/2 shift, and my 2/3 shift (with my passenger having this o-**** look the entire time). At this point, I knew Cheryl was going to be behind me, and assumed she knew what I was going to do, so I figured she would try to keep up. So when I looked up in the mirror, she was on my tail; very very close. I had just thrashed my car down the entrance ramp, and she was less than a car length behind me.
When we got to the restaraunt, she made it even worse. She said she started in 2nd gear. So yet more proof that my car is running like a dog.
On another note, this past Friday and Saturday it was warm enough to actually drive with my windows down. I noticed that under load, the car is audibly pinging below 4500rpm, which is where I'm running so lean. This observation validates the dyno's measured a/f. So I could have been pinging for who knows how long.
It's time to get serious about this and get this crap resolved. I purchased some fuel injector cleaner over the weekend and I'm gonna give that a shot(almost 19k miles now).
