Functioning NPP for $50 - Page 4 - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

xc_SS/RS · 10-29-2014, 08:30 AM

Kind of confused by this method. Using this switch, is there a way to have the flaps closed completely on start up then open up depending on throttle load or RPM?

4RSS FED · 10-29-2014, 01:47 PM

No they will be open at startup because the vacuum needed to hold them closed will not be there. I suppose you could install an additional switch to trap the vacuum before you shut off the car or some sort of reservoir tank. In reality they close pretty quick after the engine starts as can be seen in the video.

Function is dependent on engine load and not rpm.

Adding the mechanical vacuum switch just allows you to shut off the vacuum being sent to the muffler valves and 1. have them open all of the time or 2. force them open when they would normally be closed and you want a little more noise, for example idling at a stoplight. I think the function is similar to the M2W which is a remote activated electrical switch used to cut the vacuum instead of the plunger type mechanical switch used here. Maybe someone who has the M2W setup can comment on its function.

Hope this helps.

http://youtu.be/nxr-Nou58Ug

xc_SS/RS · 10-29-2014, 03:17 PM

Quote:

Originally Posted by 4RSS FED

No they will be open at startup because the vacuum needed to hold them closed will not be there. I suppose you could install an additional switch to trap the vacuum before you shut off the car or some sort of reservoir tank. In reality they close pretty quick after the engine starts as can be seen in the video.

Function is dependent on engine load and not rpm.

Adding the mechanical vacuum switch just allows you to shut off the vacuum being sent to the muffler valves and 1. have them open all of the time or 2. force them open when they would normally be closed and you want a little more noise, for example idling at a stoplight. I think the function is similar to the M2W which is a remote activated electrical switch used to cut the vacuum instead of the plunger type mechanical switch used here. Maybe someone who has the M2W setup can comment on its function.

Hope this helps.

http://youtu.be/nxr-Nou58Ug

It does thanks for the clarifications. Just as I was suspecting that at first start they're open but they shut almost immediately, then if you're giving more than 50% throttle they'll open? Then if you want loud all of the time you turn the switch off and the flaps are stuck open? Can't watch the video quite yet. Sorry for the other questions

Deke736 · 10-29-2014, 10:09 PM

Thanks for the additional info! I'm glad you guys are finding this post useful. If anyone is needing switches, shoot me a PM. I picked up a bunch at a swap meet since I know some buddies of mine are wanting to do this.

4RSS FED · 10-29-2014, 10:17 PM

You got it.

The vacuum cans need vacuum to close the exhaust valves (quiet mode). By default they are open.

I do not know what percentage is required throttle wise to start them opening. But yes if you start accelerating pretty good they will start to open and continue opening wider if you keep feeding more throttle. The amount they open is variable based on load (engine vacuum reducing) and can be at any given position based on "X" amount of vacuum. If you hammer it off the line, they will be wide open until you reduce the load. Exhaust flow on demand.

You could drive around conservatively and they may never open or you could have them opening and closing with each acceleration/deceleration or if you want them open all the time, just break the vacuum circuit by opening the manual switch.

I think the production NPP cars have some circuitry in them that also gets involved with controlling valve position based on rpm. This may be for assisting with more bottom end torque but I am unfamiliar with them.

xc_SS/RS · 10-29-2014, 10:22 PM

Looking like I will go this method but how much quieter is it with the valves closed? I would imagine fairly quiet.

I think they made the valves open all the time to make it sound meaner. I remember a video with Al saying that they did it so your neighbors know its your car or something like that.

Edit: getting a complete ZL1 cat back so install should be very easy. Does anyone know if I will run into any issues (besides the diffuser which I know I have to change) while installing on a 2010 SS?

4RSS FED · 10-30-2014, 03:48 PM

I would say it is more of a tone change. Louder, raspier and deeper with them open. From inside the car I noticed this becomes most prominent on deceleration. Either mode is great going down the freeway. It sounds good to me and this DIY thread showed another way to make it functional while saving some cash.

Quiet mode is not going to be like the minivan next to you at the stop light. Bi-modal is a cool feature, but some people just leave the valves open. At least you have an option to close the valves if needed.

4RSS FED · 10-31-2014, 07:26 PM

Quote:

Originally Posted by xc_SS/RS

Does anyone know if I will run into any issues (besides the diffuser which I know I have to change) while installing on a 2010 SS?

Only tips I can throw out there...
Use a .22 shell to knock the holes in the grommets at the back for the tubing. This makes a clean hole, back it with a 2x4 and hammer away.
7/64" tubing will work if you can not find 1/8. I used about 30 feet.
Remove the rear fascia to install the diffuser.
Lube the muffler hangers to make it easier to remove/install.
The pipe sleeve/clamps have tangs that need to be lifted. One will slide forward and one back.

Have fun.

WIKID SS · 11-18-2014, 08:58 AM

Can npp exhaust be installed without the switch? I would still run the vacuum lines to the exhaust and it should still work depending on engine load. Would I just lose the manual control?

4RSS FED · 11-18-2014, 02:36 PM

Yes to both.

ZooDad · 11-18-2014, 02:42 PM

Quote:

Originally Posted by WIKID SS

Can npp exhaust be installed without the switch? I would still run the vacuum lines to the exhaust and it should still work depending on engine load. Would I just lose the manual control?

Works well in that configuration.
That's what I am running.

WIKID SS · 11-19-2014, 05:26 PM

Thank you 4RRSS FED and ZooDad for your answers.

WIKID SS · 11-19-2014, 05:59 PM

Is the npp from a zl1 the same as on a SS or 1LE? Which one do you recommend me getting for my 2010 SS? Also which rear diffuser would I need and GM part number for it. Right now I have SLP long tube headers and high flow cats exiting to a SOLO exhaust. Car is loud but not to loud, but has a rasp to it that I don't like. No drone on highway which is good. It also is supercharged with a SLP supercharger. My question is, can I put the factory exhaust manifolds and cats back on with the NPP exhaust. Want to get it sounding to factory as much as possible. Don't mind losing some power. I also get a smell of exhaust in the car from time to time. Car was dyno at 540HP and 542ft/lbs of torque so even if I lose 25hp that's ok. What do you guys think?

Thanks

4RSS FED · 11-19-2014, 08:27 PM

Having just researched all of this, I might be able to provide some info.

The V8's use 2.5" pipe. The 2012 ZL-1 exhaust part # is 22874269 which changed to this part # 22990282.
The V8 NPP exhaust part # is 22756148. There is also a V6 NPP exhaust (additional mid section resonator and pipe size difference).
The NPP diffuser part # is 22815277

From what I was able to find out, there is a slight difference in the angle of the tips of the ZL-1 and the price tag. I have not seen the NPP and ZL-1 exhaust side by side, but I am guessing the tip difference is to match the rear fascias. I have the 269 pipes on my car. They mount up and look good on my 2012 SS with the NPP diffuser. As far as muffler internals I do not believe there is a difference but don't know for sure.

If you convert back to your stock manifolds and cats it will work fine and it will be quieter than with the long tubes and high flow cats. I have the SLP s/c running through the factory SS manifolds and cats. I have not had any problems and I am using the SLP supplied tune. If you are already tuned with the headers/cats, you might want to try it that way first?

10-29-2014, 10:09 PM	#46
Deke736 COTW 12/3/12 Drives: 2012 Ashen Gray ZL1 Join Date: Aug 2011 Location: Glen Carbon, IL Posts: 3,279	Thanks for the additional info! I'm glad you guys are finding this post useful. If anyone is needing switches, shoot me a PM. I picked up a bunch at a swap meet since I know some buddies of mine are wanting to do this. __________________

10-29-2014, 10:22 PM	#48
xc_SS/RS Drives: 2010 Camaro SS/RS Join Date: Mar 2014 Location: somewhere in MD Posts: 4,883	Looking like I will go this method but how much quieter is it with the valves closed? I would imagine fairly quiet. I think they made the valves open all the time to make it sound meaner. I remember a video with Al saying that they did it so your neighbors know its your car or something like that. Edit: getting a complete ZL1 cat back so install should be very easy. Does anyone know if I will run into any issues (besides the diffuser which I know I have to change) while installing on a 2010 SS? Last edited by xc_SS/RS; 10-30-2014 at 02:37 PM.

10-29-2014, 08:30 AM	#43
xc_SS/RS Drives: 2010 Camaro SS/RS Join Date: Mar 2014 Location: somewhere in MD Posts: 4,883	Kind of confused by this method. Using this switch, is there a way to have the flaps closed completely on start up then open up depending on throttle load or RPM?

10-29-2014, 01:47 PM	#44
4RSS FED Now Compressing Air Drives: 2012 Join Date: Feb 2014 Location: California Posts: 24	No they will be open at startup because the vacuum needed to hold them closed will not be there. I suppose you could install an additional switch to trap the vacuum before you shut off the car or some sort of reservoir tank. In reality they close pretty quick after the engine starts as can be seen in the video. Function is dependent on engine load and not rpm. Adding the mechanical vacuum switch just allows you to shut off the vacuum being sent to the muffler valves and 1. have them open all of the time or 2. force them open when they would normally be closed and you want a little more noise, for example idling at a stoplight. I think the function is similar to the M2W which is a remote activated electrical switch used to cut the vacuum instead of the plunger type mechanical switch used here. Maybe someone who has the M2W setup can comment on its function. Hope this helps. http://youtu.be/nxr-Nou58Ug

10-29-2014, 10:17 PM	#47
4RSS FED Now Compressing Air Drives: 2012 Join Date: Feb 2014 Location: California Posts: 24	You got it. The vacuum cans need vacuum to close the exhaust valves (quiet mode). By default they are open. I do not know what percentage is required throttle wise to start them opening. But yes if you start accelerating pretty good they will start to open and continue opening wider if you keep feeding more throttle. The amount they open is variable based on load (engine vacuum reducing) and can be at any given position based on "X" amount of vacuum. If you hammer it off the line, they will be wide open until you reduce the load. Exhaust flow on demand. You could drive around conservatively and they may never open or you could have them opening and closing with each acceleration/deceleration or if you want them open all the time, just break the vacuum circuit by opening the manual switch. I think the production NPP cars have some circuitry in them that also gets involved with controlling valve position based on rpm. This may be for assisting with more bottom end torque but I am unfamiliar with them.

10-30-2014, 03:48 PM	#49
4RSS FED Now Compressing Air Drives: 2012 Join Date: Feb 2014 Location: California Posts: 24	I would say it is more of a tone change. Louder, raspier and deeper with them open. From inside the car I noticed this becomes most prominent on deceleration. Either mode is great going down the freeway. It sounds good to me and this DIY thread showed another way to make it functional while saving some cash. Quiet mode is not going to be like the minivan next to you at the stop light. Bi-modal is a cool feature, but some people just leave the valves open. At least you have an option to close the valves if needed.

11-18-2014, 08:58 AM	#51
WIKID SS Drives: 2010 Camaro SS Join Date: Jan 2011 Location: Hamilton, Ontario Posts: 26	Can npp exhaust be installed without the switch? I would still run the vacuum lines to the exhaust and it should still work depending on engine load. Would I just lose the manual control?

11-18-2014, 02:36 PM	#52
4RSS FED Now Compressing Air Drives: 2012 Join Date: Feb 2014 Location: California Posts: 24	Yes to both.

11-19-2014, 05:26 PM	#54
WIKID SS Drives: 2010 Camaro SS Join Date: Jan 2011 Location: Hamilton, Ontario Posts: 26	Thank you 4RRSS FED and ZooDad for your answers.

11-19-2014, 05:59 PM	#55
WIKID SS Drives: 2010 Camaro SS Join Date: Jan 2011 Location: Hamilton, Ontario Posts: 26	Is the npp from a zl1 the same as on a SS or 1LE? Which one do you recommend me getting for my 2010 SS? Also which rear diffuser would I need and GM part number for it. Right now I have SLP long tube headers and high flow cats exiting to a SOLO exhaust. Car is loud but not to loud, but has a rasp to it that I don't like. No drone on highway which is good. It also is supercharged with a SLP supercharger. My question is, can I put the factory exhaust manifolds and cats back on with the NPP exhaust. Want to get it sounding to factory as much as possible. Don't mind losing some power. I also get a smell of exhaust in the car from time to time. Car was dyno at 540HP and 542ft/lbs of torque so even if I lose 25hp that's ok. What do you guys think? Thanks

11-19-2014, 08:27 PM	#56
4RSS FED Now Compressing Air Drives: 2012 Join Date: Feb 2014 Location: California Posts: 24	Having just researched all of this, I might be able to provide some info. The V8's use 2.5" pipe. The 2012 ZL-1 exhaust part # is 22874269 which changed to this part # 22990282. The V8 NPP exhaust part # is 22756148. There is also a V6 NPP exhaust (additional mid section resonator and pipe size difference). The NPP diffuser part # is 22815277 From what I was able to find out, there is a slight difference in the angle of the tips of the ZL-1 and the price tag. I have not seen the NPP and ZL-1 exhaust side by side, but I am guessing the tip difference is to match the rear fascias. I have the 269 pipes on my car. They mount up and look good on my 2012 SS with the NPP diffuser. As far as muffler internals I do not believe there is a difference but don't know for sure. If you convert back to your stock manifolds and cats it will work fine and it will be quieter than with the long tubes and high flow cats. I have the SLP s/c running through the factory SS manifolds and cats. I have not had any problems and I am using the SLP supplied tune. If you are already tuned with the headers/cats, you might want to try it that way first?