Retrofit NPP Exhaust Onto 2015 2LT V6

[millatime84]

I made my own npp in a box, really wasn't that tough and roughly cost $65. I followed a post from corvetteforum

[Shawno72]

Originally Posted by millatime84

I made my own npp in a box, really wasn't that tough and roughly cost $65. I followed a post from corvetteforum

Any link to that?

Great read by the way. I am negotiating a deal on a npp exhaust right now. Already have the ZL1 diffuser installed. If you are gonna install the ZL1 rockers then I suggest the ZL1 diffuser over the 1LE/SS diffuser. It hangs down a tad lower and matches up better with the ZL1 rockers

[idealer]

Originally Posted by Shawno72

Any link to that?

Great read by the way. I am negotiating a deal on a npp exhaust right now. Already have the ZL1 diffuser installed. If you are gonna install the ZL1 rockers then I suggest the ZL1 diffuser over the 1LE/SS diffuser. It hangs down a tad lower and matches up better with the ZL1 rockers

Probably this post:
http://www.smokinvette.com/corvettef...ad.php?t=28948

I have done extensive research on this project reading everything I can and arguing sometimes even at the cost of sounding like a fool - that's how I learn.

[Shawno72]

Originally Posted by idealer

Probably this post:
http://www.smokinvette.com/corvettef...ad.php?t=28948

I have done extensive research on this project reading everything I can and arguing sometimes even at the cost of sounding like a fool - that's how I learn.

Great. Thank you for that

[idealer]

Originally Posted by forzasteve

One thing I would like to add, and I think you appreciate this, that with modern cars, diving in a making modifications without fully appreciating the complex nature of today's control systems, electronics and emissions ... one can get in way over one's head and cobble up the car. Not only maybe causing more problems than you fix, but degrading the car for potential resale. I expect many of us have had an experience with a previously owned vehicle where you peer into the engine bay and see stray wires going hither and yon, plugged vacuum hoses and goodness knows what all. I conclude from your postings that you give considerable thought before making a mod on your vehicles. Wish more people would have that mind set.

Best regards,

Steve

You couldn't put it any better.
Should I decide to do the vacuum thing since I cannot find or both my hands and head are too big to find the unused port at the back of the engine. I have decided to use the hose going to the brake booster (the last piece before the check valve) Now here is my thinking, I am not going to just wack a hose without thought as to how to go back to stock so I did a little research and found the part # of that hose (actually the entire hose not just the small piece) that is how it comes) So I am going to remove my original factory hose and keep it safely somewhere while I wack this one #ACDelco #176-1726 GM Part # 22784424
I am a prime member, Amazon will have it shipped for less than 30 bucks.

http://www.amazon.com/ACDelco-176-17...ype=automotive

I am always open to suggestions. Why would I spend 30 bucks instead of wack my original hose?. Well you never know when you want to sell your car in a hurry because someone is also trying to sell you a Z06 in a hurry (Trust me it happens --lol). Like Steve mentioned, unexplained mods just scares the pants off me.

[forzasteve]

The Corvette post has one of the issues that I see with retrofitting something that relies on vacuum for operation ... and that is the issue about variable vacuum levels. As the Corvette guy made note of ... open the throttle and engine vacuum declines or even entirely disappears, close the throttle and it builds up.

The Mild2Wild kit for retrofitting the NPP exhaust to a Camaro is another Rube Goldberg modification. As it comes in their packaging, it does not provide a means to stabilize the variance in vacuum and it uses long lengths of rubber tubing and the way it suggests to tap into a vacuum would have you believe that nothing could go wrong.

First, just so you know, the variance in vacuum that is present can be problematic when you are trying to control the exhaust bypass valves on your car. You don't want them opening and closing with just the mere application of throttle position. That is just plan bad implementation. If you are thinking of retrofitting an NPP exhaust to your car and retaining the vacuum actuation, there are five things you should consider.

1. Recommend you do not run long lengths of rubber tubing from the engine bay back to the rear of the car. Rubber deteriorates over time and this method of routing vacuum may lead to vacuum leaks. Recommend you run a long length of solid metal tubing ... just as the factory does. This will not cost much but it will be a bit more difficult to install vs. rubber tubing. There is a reason why factory uses metal tubing to route vacuum over long lengths.
2. Be careful how you tap into your vacuum source, (typically the engine manifold or by tee-ing off an existing vacuum tube in the engine bay). I would avoid drilling holes in the intake manifold. I think better to tap into an existing vacuum line. Read Idealer's post above.
3. Somewhere back where you intend to use the vacuum to control the exhaust bypass valves, install a small vacuum accumulator. The Camaro with the NPP system has a small plastic canister right close the vacuum solenoid valve. The use of a vacuum accumulator will provide a stable source of vacuum to eliminate the variance that is caused by opening and closing throttle. You should be able to purchase a plastic accumulator for a few bucks. Should not be big expense.
4. Put a one-way check valve on the inlet side of the vacuum accumulator so when you open the throttle it does not cause loss of vacuum in the accumulator. Again, very inexpensive.
5. Use a solenoid valve to control the vacuum to the bypass valves actuators. You can get a solenoid valve for about $20 or so. You do not need to have remote transmitter. You can control the solenoid much more efficiently with simple on/off switch mounted in the cockpit. Since you going to the trouble of doing all the rest of this, just go ahead and get a simple on/off switch to control the solenoid. Just provide a +12V to the positive side of the solenoid and fuse protect that. Then route a single wire from the ground side of the solenoid coil to one of the contacts on the switch and then ground the other contact of the switch. This eliminates the risk of a short circuit at the switch and do not need to fuse protect the wire going to the switch.

It really is critical that you take the time and effort to ensure that you do not do something to increase the risk of a vacuum leak. Your engine fuel management and emissions controls rely very heavily on vacuum and putting something in place that may cause a leak can cause problems that could be difficult to diagnose. Better to do it right the first time rather doing it over.

Oh, one last thing. Document what you are doing. You may want to return to stock and it would be really a nice gesture for a future owner to know what you have done.

Regards,


Steve

[idealer]

Originally Posted by forzasteve

The Corvette post has one of the issues that I see with retrofitting something that relies on vacuum for operation ... and that is the issue about variable vacuum levels. As the Corvette guy made note of ... open the throttle and engine vacuum declines or even entirely disappears, close the throttle and it builds up.

The Mild2Wild kit for retrofitting the NPP exhaust to a Camaro is another Rube Goldberg modification. As it comes in their packaging, it does not provide a means to stabilize the variance in vacuum and it uses long lengths of rubber tubing and the way it suggests to tap into a vacuum would have you believe that nothing could go wrong.

First, just so you know, the variance in vacuum that is present can be problematic when you are trying to control the exhaust bypass valves on your car. You don't want them opening and closing with just the mere application of throttle position. That is just plan bad implementation. If you are thinking of retrofitting an NPP exhaust to your car and retaining the vacuum actuation, there are five things you should consider.

1. Recommend you do not run long lengths of rubber tubing from the engine bay back to the rear of the car. Rubber deteriorates over time and this method of routing vacuum may lead to vacuum leaks. Recommend you run a long length of solid metal tubing ... just as the factory does. This will not cost much but it will be a bit more difficult to install vs. rubber tubing. There is a reason why factory uses metal tubing to route vacuum over long lengths.
2. Be careful how you tap into your vacuum source, (typically the engine manifold or by tee-ing off an existing vacuum tube in the engine bay). I would avoid drilling holes in the intake manifold. I think better to tap into an existing vacuum line. Read Idealer's post above.
3. Somewhere back where you intend to use the vacuum to control the exhaust bypass valves, install a small vacuum accumulator. The Camaro with the NPP system has a small plastic canister right close the vacuum solenoid valve. The use of a vacuum accumulator will provide a stable source of vacuum to eliminate the variance that is caused by opening and closing throttle. You should be able to purchase a plastic accumulator for a few bucks. Should not be big expense.
4. Put a one-way check valve on the inlet side of the vacuum accumulator so when you open the throttle it does not cause loss of vacuum in the accumulator. Again, very inexpensive.
5. Use a solenoid valve to control the vacuum to the bypass valves actuators. You can get a solenoid valve for about $20 or so. You do not need to have remote transmitter. You can control the solenoid much more efficiently with simple on/off switch mounted in the cockpit. Since you going to the trouble of doing all the rest of this, just go ahead and get a simple on/off switch to control the solenoid. Just provide a +12V to the positive side of the solenoid and fuse protect that. Then route a single wire from the ground side of the solenoid coil to one of the contacts on the switch and then ground the other contact of the switch. This eliminates the risk of a short circuit at the switch and do not need to fuse protect the wire going to the switch.

It really is critical that you take the time and effort to ensure that you do not do something to increase the risk of a vacuum leak. Your engine fuel management and emissions controls rely very heavily on vacuum and putting something in place that may cause a leak can cause problems that could be difficult to diagnose. Better to do it right the first time rather doing it over.

Oh, one last thing. Document what you are doing. You may want to return to stock and it would be really a nice gesture for a future owner to know what you have done.

Regards,


Steve

Very good advice, which is why my neighbors will have to deal with the always open valves for now.

[millatime84]

http://www.corvetteforum.com/forums/...st-guru-s.html

I used Dano523 direction and bought most of the part listed. I couldn't get the cap off the back of my intake so I tapped a different vacuum source.

To be honest, there isn't a huge difference between open an closed. I typically only have it. CLosed when I'm in the neighborhood and cruising on the interstate.

[Shawno72]

Originally Posted by idealer

Very good advice, which is why my neighbors will have to deal with the always open valves for now.

Yeah I'm leaning on leaving them open for now as well.

[idealer]

Behold the most comprehensive NPP thread especially how and where factory gets its air and how. Pretty easy if you are willing to spend 60 bucks to make it look clean. Factory is mostly hoses too.
http://www.camaro5.com/forums/showth...=376190&page=2
Found this via Google while searching for 1/8 metal vacuum hose. Go figure

[Shawno72]

Originally Posted by idealer

Behold the most comprehensive NPP thread especially how and where factory gets its air and how. Pretty easy if you are willing to spend 60 bucks to make it look clean. Factory is mostly hoses too.
http://www.camaro5.com/forums/showth...=376190&page=2
Found this via Google while searching for 1/8 metal vacuum hose. Go figure

Finally lol. Thanks again!

[SinginHawk]

Thanks for all of the great insight and references everyone! I don't think I could have come to my conclusion without you all.

I have decided to just buy the NPP system used.

If I have issues with drone then I will attempt to address them as with any other exhaust; High Flow Cats and a Magnaflow Resonated X-Pipe.

If I have issues with the volume then I will worry about retrofitting vacuum controls.

Again, thanks for all of the insight! Hopefully this becomes a resource that other people can use in the future to help make up their mind with regards to priorities and feasibility.

[idealer]

Just got back from the muffler shop. Installed mine today. It is day and night compared to stock. Not really sure what people call drone so I cannot comment on that but the sound to me and how it is quite but distinct until you step on it is priceless. I will be running the vacuum line later- complete with a vacuum tank just like the factory ones. The one major diff will be that I will also be able to control mine with the Corvette light switch. I even have the hose with the check valve for the vacuum tap delivered today. Thank you all especially FORZASTEVE who made me take a better look and come up with a better solution by combining knowledge already available in the forum.

[forzasteve]

Originally Posted by idealer

Just got back from the muffler shop. Installed mine today. It is day and night compared to stock. Not really sure what people call drone so I cannot comment on that but the sound to me and how it is quite but distinct until you step on it is priceless. I will be running the vacuum line later- complete with a vacuum tank just like the factory ones. The one major diff will be that I will also be able to control mine with the Corvette light switch. I even have the hose with the check valve for the vacuum tap delivered today. Thank you all especially FORZASTEVE who made me take a better look and come up with a better solution by combining knowledge already available in the forum.

Sweet looking ride you have there ...

I agree, the NPP makes such a huge difference. I really think GM should have made it standard equipment.

Best regards,

Steve