Engine Sound Management
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,950
Likes: 12,363
From: NE South Carolina
Even when you have NPP the outside exhaust valves stay closed up to a certain rpm from what I have observed. Even if in Track, try this test:
If a standard shift, put the car in direct drive, 4th gear and drive at ~1300 rpm. Then floor the throttle and at ~1700 rpm you’ll hear them open. Guess if you have an automatic put it in Manual Mode and direct drive 6th gear and do the same. I’m assuming in Manual Mode it won’t drop down a gear or two when floored.
Sure sounds like the NPP valves open to me! I have my NPP set at always Track regardless of my drive mode. But have tested and it does the same flooring in 4th at 1300 rpm if I put the drive mode in Track.
That is why some folks pull the NPP fuse or buy the Mild to Wild remote relay that essentially “pulls the fuse” when you press a button.
In Touring mode where the NPP valve open is about ~2500 rpm from my observation.
If a standard shift, put the car in direct drive, 4th gear and drive at ~1300 rpm. Then floor the throttle and at ~1700 rpm you’ll hear them open. Guess if you have an automatic put it in Manual Mode and direct drive 6th gear and do the same. I’m assuming in Manual Mode it won’t drop down a gear or two when floored.
Sure sounds like the NPP valves open to me! I have my NPP set at always Track regardless of my drive mode. But have tested and it does the same flooring in 4th at 1300 rpm if I put the drive mode in Track.
That is why some folks pull the NPP fuse or buy the Mild to Wild remote relay that essentially “pulls the fuse” when you press a button.
In Touring mode where the NPP valve open is about ~2500 rpm from my observation.
Last edited by JerryU; Sep 14, 2018 at 11:47 AM.
Instructor
Joined: Apr 2015
Posts: 226
Likes: 42
From: St-Colomban Quebec
With sound management set to Track, when I start the engine, it barks, when it's set to Stealth, starting the engine makes a sound comparable to starting a regular v6/v8 car with regular muffler.
Le Mans Master
Joined: May 2010
Posts: 5,347
Likes: 2,401
As said if you have NPP it controls when the valves open. I believe as you go from eco to track they progressively open earlier in the RPM range. I installed the mild to wild switch and keep mine open most of the time. I only close them early in the morning or late at night for the neighbors.
Drifting
Joined: Apr 2013
Posts: 1,743
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From: Saint Clair Shores Mi
I definitely hear a difference when in park at idle when switching from stealth to track mode. I just pulled the fuse, the heck with it. I like the louder exhaust with the borla x-pipe. Although, it does sound crappy (A8) when AFM is active switching from V4 to V8 constantly on the highway.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,950
Likes: 12,363
From: NE South Carolina
As said if you have NPP it controls when the valves open. I believe as you go from eco to track they progressively open earlier in the RPM range. I installed the mild to wild switch and keep mine open most of the time. I only close them early in the morning or late at night for the neighbors.
Therefore put the car in Track Mode and drive in 4th if you have an M7 or 6th (direct drive) if you have an A8 and drive at ~1300 rpm and floor it.
With the switch set at Mild you should hear a stepped change in sound at 1700 rpm as it goes loud.
With the switch set at Wild the sound should be just a bit louder but not a step change from quite to loud at 1700 rpm.
Curious as some state when set at Track the NPP valves are always open. It even states that in the 2016 Service Manual. But I believe they stay closed until about 1700 rpm from my observation of the dramatic sound change at that rpm. In Sport that change in sound occurs at about 2500 rpm.
Last edited by JerryU; Sep 14, 2018 at 05:41 PM.
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Le Mans Master
Joined: May 2010
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Since you have a Mild to Wild switch could you run the test I outlined in my post #3, when you have a chance?
Therefore put the car in Track Mode and drive in 4th if you have an M7 or 6th (direct drive) if you have an A8 and drive at ~1300 rpm and floor it.
With the switch set at Mild you should hear a stepped change in sound at 1700 rpm as it goes loud.
With the switch set at Wild the sound should be just a bit louder but not a step change from quite to loud at 1700 rpm.
Curious as some state when set at Track the NPP valves are always open. It even states that in the 2016 Service Manual. But I believe they stay closed until about 1700 rpm from my observation of the dramatic sound change at that rpm. In Sport that change in sound occurs at about 2500 rpm.
Therefore put the car in Track Mode and drive in 4th if you have an M7 or 6th (direct drive) if you have an A8 and drive at ~1300 rpm and floor it.
With the switch set at Mild you should hear a stepped change in sound at 1700 rpm as it goes loud.
With the switch set at Wild the sound should be just a bit louder but not a step change from quite to loud at 1700 rpm.
Curious as some state when set at Track the NPP valves are always open. It even states that in the 2016 Service Manual. But I believe they stay closed until about 1700 rpm from my observation of the dramatic sound change at that rpm. In Sport that change in sound occurs at about 2500 rpm.
Le Mans Master
Joined: Oct 2014
Posts: 8,672
Likes: 2,726
From: Atlanta GA
They also close above a certain rpm while cruising when AFM kicks in the car just would not sound good with NPP open in 4 cylinder mode . Turn AFM off with a device like the Range along with a Mild to Wild switch and the NPP in the C7 sounds just as good if not better than my C6 LS3 with NPP
I also use to think that the NPP was to quiet until I got the opportunity to hear my car wide open with someone else driving ... I think the active noise canceling is fooling us ....lol
Dave
I also use to think that the NPP was to quiet until I got the opportunity to hear my car wide open with someone else driving ... I think the active noise canceling is fooling us ....lol
Dave
Last edited by Dcasole; Sep 14, 2018 at 06:08 PM.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,950
Likes: 12,363
From: NE South Carolina
Yes there is a step when the valves are closed. They are closed at that RPM even in Sport or Track mode. That’s why I put in the switch. Otherwise there is no reason for the Mild to Wild switch. It’s still not quite loud enough for me at idle so I just picked up the Borla Xpipe. Hoping that does the trick for me.
Race Director
Joined: Aug 2015
Posts: 12,252
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From: SE WI
I noticed the same thing on my new Grand Sport. My engine sound is always in Track but you can clearly hear the sound increase when I suddenly accelerate from a low rpm. Not sure why they do that.
Last edited by Zjoe6; Sep 15, 2018 at 06:47 PM.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,950
Likes: 12,363
From: NE South Carolina
I had installed a simple toggle switch on my C6 NPP to bypass the fuse when desired. If the butterflies were set open there was an annoying drone at Interstate speeds. I'd flip the switch.
Advanced
Joined: Jun 2018
Posts: 96
Likes: 40
In Vehicle Settings - Engine Sound Management, if you select Track it will open the valves to the full open position, and will remain in that position regardless of the Driving Mode. While in this setting, you can look into the two outboard exhaust outlets and see the butterfly valves in the full open position, engine off or running.
Burning Brakes
Joined: Aug 2009
Posts: 1,021
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From: Sturgeon County Alberta
In Vehicle Settings - Engine Sound Management, if you select Track it will open the valves to the full open position, and will remain in that position regardless of the Driving Mode. While in this setting, you can look into the two outboard exhaust outlets and see the butterfly valves in the full open position, engine off or running.
Team Owner
Joined: Aug 2007
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From: I live my life by 2 rules. 1) Never share everything you know. 2)
St. Jude Donor '11-'12-'13, '16-'17-'18
In Vehicle Settings - Engine Sound Management, if you select Track it will open the valves to the full open position, and will remain in that position regardless of the Driving Mode. While in this setting, you can look into the two outboard exhaust outlets and see the butterfly valves in the full open position, engine off or running.
Le Mans Master
Joined: Oct 2014
Posts: 8,672
Likes: 2,726
From: Atlanta GA
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,950
Likes: 12,363
From: NE South Carolina
In Vehicle Settings - Engine Sound Management, if you select Track it will open the valves to the full open position, and will remain in that position regardless of the Driving Mode. While in this setting, you can look into the two outboard exhaust outlets and see the butterfly valves in the full open position, engine off or running.
Yes that is an observation BUT they do close!
When in Track Mode, try flooring it from ~1300 rpm in 4th gear (in an M7) and you'll hear the stepped sound difference at 1700 rpm!
Yes that is an observation BUT they do close!
When in Track Mode, try flooring it from ~1300 rpm in 4th gear (in an M7) and you'll hear the stepped sound difference at 1700 rpm!
Yep in addition to my direct drive test, flooring at ~1300 rpm and hearing the step change in sound at ~1700 rpm, another observation is the black on the two outer exhaust tips. A major cause is when the valves are closed and the mufflers cool water and soot collect behind them. When they open it dumps that "stuff" leaving a deposit.If someone who has pulled the fuse would try the direct drive 4th gear in an M7 and floor it at ~1300 and report the sound difference (or lack there of) at 1700 rpm- that would prove that even if set at always Track or Track setting (have tried the test in both) that the butterflies are shut at most times (perhaps not at idle) below 1700 rpm.
Last edited by JerryU; Sep 16, 2018 at 08:57 AM.