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I thought I read in here that driving in Sport mode, for example, with the sound set on Tour doesn't reduce the power curve. I'm having a hard time understanding that because part of the power comes from more efficient exhaust...and in Touring, the exhaust baffles are not fully open (except during full throttle, of course). Or do the baffles contribute less than I think to the overall power equation?
The reason is the valves aren't closed all the time in Tour Mode. Anytime you are operating the throttle aggressively the valves are open.
This description of exhaust valve operation is taken from the Exhaust Section of the Factory Service Manual:
If you notice the paragraph on the second page one thing will close the valves even when set in track mode and that is when the engine operates in V4 mode. That means when an A8 switches to V4 mode during various driving modes the exhaust will close. If you have an M7 this only happens in Eco Mode so if the Exhaust is Set to Track using the Engine Sound Management options under the Settings Menu the exhaust will be open all the time except when driving in Eco where it will close anytime the engine switches to V4 operation.
^ ^ ^
Well, yes thank you for the technical explanation of how/why the sound management and exhaust system work. Interesting.
But my question is basically if I'm in Sport mode with the sound management system in Tour mode, would I get more power if I have the sound management system in Sport mode. Pineapple, above, says +5 HP. That doesn't seem to be my experience, but that's why I'm asking. And really, at full throttle I don't think sound management settings matter because the tailpipe valves are open regardless. I'm asking more about normal acceleration but not a floored condition.
But my question is basically if I'm in Sport mode with the sound management system in Tour mode, would I get more power if I have the sound management system in Sport mode.
But my question is basically if I'm in Sport mode with the sound management system in Tour mode, would I get more power if I have the sound management system in Sport mode.
No
Chevy does not make the claim that open Exhaust valves will increase horsepower, however I know that my LS3 C6 with NPP, was claimed to have 6 hp more due to those valves
FWIW
The dual mode exhaust NPP has 5 more horsepower than the non-NPP, so that is where the 5 HP difference we are discussing is coming from. The power curve (engine) will be set for Sport while you have your NPP (exhaust) set to Touring. When you go WOT, the valves will open to give you the extra "unnoticeable" 5 HP.
Despite what the manual says, the valves are NOT always open in Track mode. They just open earlier (lower RPM) than any of the other mode. Pull fuse 42 (on '17 models) and you'll notice the difference. That is why I pulled my fuse, because the sound of the valves opening at lower RPM in Track mode is a bit annoying to me. I think they write it into the manual that way just to make it simpler for the average person to understand.
Chevy does not make the claim that open Exhaust valves will increase horsepower, however I know that my LS3 C6 with NPP, was claimed to have 6 hp more due to those valves
FWIW
I thought I read in here that driving in Sport mode, for example, with the sound set on Tour doesn't reduce the power curve. I'm having a hard time understanding that because part of the power comes from more efficient exhaust...and in Touring, the exhaust baffles are not fully open (except during full throttle, of course). Or do the baffles contribute less than I think to the overall power equation?
First the NPP valves are either fully opened or fully closed.
In Track mode (where I have mine set regardless of driving mode) they open at ~1700 rpm. In Touring mode my experience is they open fully at ~2500 rpm.
So if you look at the C7 power curves thy start at ~2500 rpm! In fact that extra 5 hp is no doubt after 4000 to 5000 rpm where exhaust restrictions are meaningful. ! Therefore makes no difference as the NPP will be open when you would get that extra 5 hp! Also agree with another poster you can't "feel" 5 hp!
St. Jude Donor '13-'14-'15-'16-'17-'18-'19-'20-'21-'22-'23-'24
Originally Posted by JerryU
First the NPP valves are either fully opened or fully closed.
In Track mode (where I have mine set regardless of driving mode) they open at ~1700 rpm. In Touring mode my experience is they open fully at ~2500 rpm.
So if you look at the C7 power curves thy start at ~2500 rpm! In fact that extra 5 hp is no doubt after 4000 to 5000 rpm where exhaust restrictions are meaningful. ! Therefore makes no difference as the NPP will be open when you would get that extra 5 hp! Also agree with another poster you can't "feel" 5 hp!
According to the manual shown in post #3 it says the valves are always open in track mode. It sounds like they are not open at all times.
Y'know what would be nice, is if we could program EACH driving mode with its own sound management mode. So, if I want to blow the sound out, I go to track for example, but otherwise, I can be in Touring sound for the other driving modes.
the 5 HP gain is from the adjustable exhaust. It will be 5HP no matter what mode you are in because the computer opens the exhaust after a programmed RPM. So at WOT they all sound the same after a certain RPM, and that's when max HP peaks.
Go try it yourself, it's fun. Go WOT in tour mode, sport mode and track mode, and make sure you stay in it until redline. It'll be the same in all setttings!
According to the manual shown in post #3 it says the valves are always open in track mode. It sounds like they are not open at all times.
Yep shows that in the 2015 Service Manual. Did not bother to check my 2014 Service Manual BUT from my and observation by others, that is NOT correct. That is why folks buy a Mild-To-Wild remote activated switch or pull the fuse. If that were the case just need to set NPP for "always Track" regardless of drive mode. That is how I have mine set. Have a spot on my street where I pass a friends house that is around a bend in the road. If in a lower gear, as I am most of the time in the morning on the 25 mph road, when it goes past ~1700 rpm as I use more accelerator around that corner you can hear them open. I get accused of "gunning the engine" when I pass their house!
In addition, on the Intestate in 7th at 78 mph the engine is at ~1625 rpm and the valves are closed. No drone. Just a bit more throttle and they open-some drone. On my C6 Z51 with NPP I added a switch so I could turn the butterflies off and on at will (essentially pulling the fuse.) At 75 mph had to close them or the drone was excessive and even Janis Joplin signing "Cry Baby" could not overcome the sound!
That is my observation as is the ~2500 threshold in Touring. As I mentioned, I have my NPP set for always Track whatever the drive mode. That as well as steering are options in the menu. I now drive in Sport (with the software upgrade) so perhaps it's different than driving in Track Mode. But considering I have found other errors in my 2014 Service Manual it could just be a misstatement.
The only way to have them open all the time that I am aware of is to pull the fuse, install a switch to bypass the fuse or get a Mild to Wild remote switch that essentially is a swithable way to "pull the fuse." If it were as simple as just setting NPP as "always Track" they would never sell that product and folks would not be pulling the fuse.
08-16-2018, 03:58 PM
Same power regardless of sound setting?
