xp800

That would work, and this is what Theta has done in his setup. From his description earlier in this thread, it was a bit of work due to confined space.

An auto and manual should not sound different in V8 mode with NPP valves open. Unless the auto owner pulled fuse 32 as well and then the sound from the rear would sound like a$$ in V4 mode since it spends more time there. But that said, auto and manual should sound no different when operating/configured the same way.

Greg Quillen

Lime Rock Park. This stupid church took them to court. They have to keep it under 86db .. They get a few unmuffled days for races

Yea. Looking at it. To try keep it shut i noticed no power is open

Greg Quillen

Need a battery to power shut lol

xp800

And a PWM circuit to control it.

xp800

Updated OP.

Turns out that the 2015 NPP fuse moved to 42 from 41. As if it wasn't confusing enough...

phantasms

Can someone explain to me exactly why the above doesn't work? I understand that "circuit closed" will not result in valves closed all the time. However wouldn't this switch be exactly the same as removing or replacing the fuse? Circuit open and no more 1700rpm issues. Circuit closed and no potential for highway drone? I don't understand why all the fuss and not just go with the above? If the issue is that it's in the fuse box under the hood that's not an issue. I, may have, wired a fuse switch to the box under the hood on my C6Z that cut off my license plate light and side markers.

Sorry if I'm being the C7 NPP n00b here.

Best,
Gene

Theta

Gene, you're exactly right. This is how I have mine.

The only difficulty lies in routing wiring into the fuse box, which can be accomplished with O-rings and quick disconnects (and an in-line fuse).

phantasms

Thank you! Additionally couldn't one program the system to keep the valves closed in all settings. Then set the system to Auto. This might make a loud to stealth switch out of the fuse switch, no?

Do you, or anyone else, have a DYI photo thread on the best way to do the install with said O-rings...ect?

Thank you for all the research and work you and the others have put into this.

Best,
Gene

Theta

Not at the moment. We don't have access to the BCM (Body Control Module) to start attacking those settings.

I don't have pictures, but can take some in a few weeks for you. Essentially, you can run 2 14ga sheathed hook-up wires in through a small O-ring (so, one in, one out to be completely waterproof), then terminate into a neutered fuse (cut through the center). A small drill bit works wonders for this task.

Then, simply run the wiring into the car using the same old 'left of the clutch pedal' hole, and choose where to mount your switch. Install a properly-rated fuse in-line with one the wires, and you have an easy on/off solution!

Fugitive C7

Hopefully we get this soon, the sound from my car will peel the skin off your face when i pass you, and the damned thing opens at 3500 (ish) rpm in touring mode. For now, I'm stuck driving only in touring mode in most conditions because you can hear my car screaming from a mile away (seriously)

LT headers, no cats, etc...

Interestingly, my car (perhaps from the dramatically increased torque demand) is ALWAYS OPEN in track mode, sport mode seems barely more quiet at idle, but it's essentially always "melt your face open" as well. Just mentioning this as there is potential that the changes made to my tune might be applicable to this groups needs. You cannot mistake open/closed in my car, the difference is STAGGERING.

phantasms

FWIW I set my Z06's exhaust sound settings to track for all modes. I don't experience any type of change at 1,700. It does sound like it's completely open all the time.

Another new Z06 owner, who traded in his C7 for it, said the NPP seems to work differently and stay open.

I have no science on this at this time but it's what I've experienced. Just wanted to pass it along.

Best,
Gene

xp800

Gene,

Thank you for adding some useful new insights and a bit of new excitement for us NPP geeks.

Just so I'm clear on what you've done... You have gone into Engine Sound Management and set it to Off. This is what I interpret from your 'race mode' comment.

The best way to notice the behavior anomaly with ESM off, if it exists in the Z06, is to lazy shift from 3 into 4 so that the revs fall well below 1500rpm. Then slowly tip into the throttle, and then right at 1700rpm the sound should go from muted to V8 glory in an instant.

Who knows... Maybe the Corvette engineers have been reading this thread and decided to have off=off finally.

Elite275

Yes, that would be awesome! Otherwise, it looks like I'll be doing what Theta did after I get the longtubes on.

xp800

Turns out that the Z06 has unique NPP settings! Maybe this will find it's way to the Singray NPP?

Thanks to occar:

https://www.corvetteforum.com/forums...post1588492970

0v3rc10ck3d

Can someone clarify the 1700rpm issue for me?

Are the NPP valves closed below 1700rpm regardless of ESM or Drive mode selection?

I want to idle loudly! and have lots of pops and burbles like i used to, right now I just leave it in sport mode but I feel my C6 with mild to wild was much louder.

xp800

If in Sport (I think) or definitely in Track or with Engine Sound Management Off, the NPP valves will be open at Idle. And certainly the fuse pull leaves NPP open. In Touring, Eco, and Weather, the NPP valves are closed at idle.

Item #8 in the first post explains the behavior best. The 1700RPM issue does not happen at idle, it happens on manual cars on upshifts or driving in upper gears when RPMs fall below 1700RPM. Then the valves close and then reopen at 1700RPM when accelerating.

Indy-hp

subscribed

thegame

fuse 42 for 2015 correct ??

Daemek

I don't know anything about cars. I tried doing a google search for fuse 42 for 2015 corvettes but where is it located? Are the fuses labeled by number when you find it? Just wanna make sure I pull the right one.

Elite275

The fuse is in the box under the hood on the passenger side. There are pics in the thread about location or in the manual.