I've seen mentions of a valve in the muffler that opens under power. Is there a way to keep this open permanently. Seems it might help the sound for no bucks!

 

I'm sure it would be louder, but,.........listen to how it works and what it does.

When pressure inside the main muffler is low (at idle or constant speed), the control valve is closed. Then, when pressure inside the main muffler is high (during acceleration), the control valve is opened. Reducing the exhaust system back pressure helps maintain a consistent, progressive torque curve. In other words you stand to kill off some of your low end torque. But in the same breath, know that the coupe gets a good old fashioned high performance muffler (ok, the factories idea of high performance, no variable capacity stuff).

I found a pic diagram of the inside of the variable capacity muller, I'm going to try and link it, hope it show's





Ivry 6mt sed
Crawford Pleneum
Injen CAI
22" resonator
Cusco sway bars
350Z springs&struts
Enkei RPM2

 

Thanks!

I do have the sedan on order. Does your coupe muffler comment apply to the sedan also?

 

I have been asking in the forums, and even emailed Stillen, to see how a complete new aftermarket exhaust (without valve) would impact the low-end torque that makes these cars so fun. I have not received solid answers. Everybody talks about HP increases, but no mention of torque. Either no one knows, or don't want to discuss torque loss, if it would/does occur.

<P ID="edit"><FONT class="small"><EM>Edited by don1 on 09/13/03 03:25 PM.</EM></FONT></P>

 

gwise (Newbie)
09/13/03 02:14 PM

Thanks!

I do have the sedan on order. Does your coupe muffler comment apply to the sedan also?
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The coupe's muffler does NOT have the variable capacity design, it's more of a higher performance design. Hence it would be a natural flow of event's for someone to replace the sedan's muffler with a aftermarket higher performance design, for someone chasing more power that is. If you want a deeper exhaust note, don't touch the muffler all you need to do if remove the stock premuffler (in the middle of the car) and replace it with a 22" straight threw resonator like I did, only cost me $70 and it does exactly what you want, with a slight gain in performance. I love the deeper sound and NO bad sound qualities what so ever.

Here is a cut and paste from Infiniti's web site that will explan, in their own words how the sedan and coupe muffler are different.

G35 coupe
Tuned Exhaust
With its free-flow design, exhaust flow is constant and high-end power is optimized. But that isn't all. The note of the dual-tipped muffler is also tuned for a seductive growl at idle and a throaty song with the throttle opened wide.

G35 sedan
Variable capacity muffler
A pressure valve automatically opens the exhaust flow wide at higher rpm to boost high-end power output and gives the G35 Sport Sedan the growl of a hot rod. When rpm is reduced, as during idle, the valve adjusts to hush the muffler to nothing more than a soothing hum. BUT!! you have to add on my previous comments on how low end torque is helped by the variable capacity design.

Hope that helps

Ivry 6mt sed
Crawford Pleneum
Injen CAI
22" resonator
Cusco sway bars
350Z springs&struts
Enkei RPM2

 

don1 (Newbie)
09/13/03 03:19 PM

I have been asking in the forums, and even emailed Stillen, to see how a complete new aftermarket exhaust (without valve) would impact the low-end torque that makes these cars so fun. I have not received solid answers. Everybody talks about HP increases, but no mention of torque. Either no one knows, or don't want to discuss torque loss, if it would/does occur.
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I hear ya, and when dyno's are shown they graph mysteriously starts at 2.5K or 3k. I want to see 1k to redline.
Here's a dyno off Injen's site it's of their SES exhaust w/ Injen cold air intake. If the rumor about Injen creating a SES system come's true, than the torque curve will give you a idea.

I'm sure their are other posted dyno's on my350Z.com that will give you a better picture. But again, they usually start at 2k to 2.5K.



Ivry 6mt sed
Crawford Pleneum
Injen CAI
22" resonator
Cusco sway bars
350Z springs&struts
Enkei RPM2