Converting SS exhaust to NPP Exhaust

[jrhagen]

ADM has a kit.

[dentnshell]

Disclamer! I have no experience with NPP in a box... But my understanding is that it is NOT rpm dependent.
Simply - Loud or Vacuum operated
Vacuum operated does have some open and closed action similar to actual NPP, but I think closer would be a RPM window switch that operates the solenoid at RPM's that you determine.

[SomeGeoffGuy]

Originally Posted by dentnshell

If you want true npp then you will need a few items...

I have put together some pricing from Amazon or ebay!
$55 - RPM window switch
$36 - ACDelco 214-474 GM Original Equipment Turbocharger Wastegate Solenoid ( this would not require special barbed fittings, price also includes a pigtail to hook it up. )
$17 - 50’ Gates vacuum hose
$15.35 - RM01 1 Channel Wireless Control On/Off ( basically the relay and wireless mild to wild control)
$8.39 - E Support 12v Car Add-a-circuit Fuse TAP Adapter Mini ATM APM Blade Fuse Holder Pack of 5
$7.99 - Dorman 47380 Vacuum Connector Value Pack, 65 Piece (Really only need a single vacuum Tee)

The wastegate solenoid is a three way solenoid. It will allow for vacuum to be pulled when on (quite) and it will vent to air when off (vent to air will allow for the valves to actually spring back)

An RPM window switch is not really needed unless you want it to operate like factory NPP and be controlled by RPM ebay has a RPM switch in the $45 -$55 range depending on how much control you want. This will allow you to have the NPP come on (quiet down) at a set RPM, say 1500. And go off again (get loud) at another RPM say 3500.

You can also add a second solenoid that will not allow the first to vent to air. This would keep the NPP engaged and keep it quiet at idle or at WOT. This would also require a three way switch. (probably instead of the wireless controller)


It all depends on how much control you want.

Great write-up! I think I would wire this in with a 3 position switch - valve open (off), valve closed (on1), and window switch (on2). That would cover just about every way you would want it.

-Geoff

[tnharley]

Great write-up Denton (dentnshell)

[Camaro Dude]

Originally Posted by Homeless Man

Why don't u just buy another exhaust. Many sound better and will be easier to install.

lol@many

Plz do tell, I'm all ears👂🏻 .....

[Camaro Dude]

Originally Posted by dentnshell

Disclamer! I have no experience with NPP in a box... But my understanding is that it is NOT rpm dependent.
Simply - Loud or Vacuum operated
Vacuum operated does have some open and closed action similar to actual NPP, but I think closer would be a RPM window switch that operates the solenoid at RPM's that you determine.

Indeed, regarding the NPP in the box.

I think it was Forza dude, a respectable vendor on here who makes and sells 2 and 3-way NPP control switches, who said that the flaps actuation would be a bit less responsive to gas pedal command with the NPP in a box, versus the true OEM full hog setup, as installed from the factory.

[dentnshell]

regarding the GM 3-way valve ( or any three way for that matter) You can change how you connect the vacuum hoses to change the way your NPP switch works.

This is especially important if you are using a wireless switch. Since it does retain settings once power is removed.

If you connect the muffler side of your engine side (vacuum source) up to the vent to air port, you will essentially turn NPP on by default, then when you turn the switch on it will close the valve and the normal input will be vented to air.

What does this do... It make the default setting NPP and the powered setting Wild vs default Wild and powered NPP.

It is all about which way you want the sound.

All this being said. I now have Long tubes with HF Cats and my DIY NPP. Dynamite ( in the trunk spare tire location. At highway speeds there is VERY LITTLE difference in sound between the settings inside the car. The is a more noticeable difference in town driving.

The NPP is a cool idea and I like it. I would imagine that Flowmasters or Borla-S type has a deeper sound than NPP.

[Jay462]

Originally Posted by dentnshell

If you want true npp then you will need a few items...

I have put together some pricing from Amazon or ebay!
$55 - RPM window switch
$36 - ACDelco 214-474 GM Original Equipment Turbocharger Wastegate Solenoid ( this would not require special barbed fittings, price also includes a pigtail to hook it up. )
$17 - 50’ Gates vacuum hose
$15.35 - RM01 1 Channel Wireless Control On/Off ( basically the relay and wireless mild to wild control)
$8.39 - E Support 12v Car Add-a-circuit Fuse TAP Adapter Mini ATM APM Blade Fuse Holder Pack of 5
$7.99 - Dorman 47380 Vacuum Connector Value Pack, 65 Piece (Really only need a single vacuum Tee)

The wastegate solenoid is a three way solenoid. It will allow for vacuum to be pulled when on (quite) and it will vent to air when off (vent to air will allow for the valves to actually spring back)

An RPM window switch is not really needed unless you want it to operate like factory NPP and be controlled by RPM ebay has a RPM switch in the $45 -$55 range depending on how much control you want. This will allow you to have the NPP come on (quiet down) at a set RPM, say 1500. And go off again (get loud) at another RPM say 3500.

You can also add a second solenoid that will not allow the first to vent to air. This would keep the NPP engaged and keep it quiet at idle or at WOT. This would also require a three way switch. (probably instead of the wireless controller)


It all depends on how much control you want.

I registered on this forum specifically to thank you for the ideas, but to also warn others to not use that ACDelco solenoid. It is not designed for constant-on duty cycle and will fail. I did it, and that happened. I used a MAC solenoid valve for my corvette in this application. It's better and cheaper. DIY build thread here:

http://www.corvetteforum.com/forums/...ne-intake.html

[dentnshell]

Originally Posted by Jay462

I registered on this forum specifically to thank you for the ideas, but to also warn others to not use that ACDelco solenoid. It is not designed for constant-on duty cycle and will fail. I did it, and that happened. I used a MAC solenoid valve for my corvette in this application. It's better and cheaper. DIY build thread here:

http://www.corvetteforum.com/forums/...ne-intake.html

Thanks for the update.... I wouldn't know as I have it hooked up so that the solenoid is "off" and in "Loud" mode... unless she wants it quiet... Which is rarely... If I have to replace it, I will take a look at the MAC

THANKS!

[jrhagen]

I have it controlled by wireless remote through the garage door opener buttons.

[Bow94z]

Who sells NPP in a box?
Adding NPP mufflers to SS and want to control flaps

[punk5150]

Gs creations. This piece is great if you want to control your exhaust. Converted my L99 years ago. Love the NPP exhaust with long tubes.

[Rocky1974]

Originally Posted by jrhagen

I have it controlled by wireless remote through the garage door opener buttons.

That's how I did mine. I used all the factory vacuum lines and solenoid from the donor car and a cheap ebay wireless switch. It works like a charm. The only problem is it takes up 2 of my 3 Homelink buttons. I wish I had a wireless switch that I could control with one button.