Custom built NPP Setup for a 2011 SS car - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

SScylla · 12-17-2021, 01:37 PM

hi guys, i was doing some brainstorming about my car.
i live in germany and we have kinda strict exhaust laws, or not strict but oddly specific.

to cut to the chase:

my car can be as loud as it wants, but: it has to have a maximum of 76decibel at 50-70 kph (30ish mph to 40ish) and it has to be quiet with a max of 76 decibel at 3750 rpm.

to achieve that, i thought about controlling the valves in these parameters of a NPP exhaust because noone will build such an exhaust in germany afik.

lets say i use the stock vaccum lines and an accumulator tank to store vacuum like the zl1 does. then i can hook that up to a 5/2way valve to control the flow of vacuum. from open to close
and open up again if needed.

i could also use a rpm controlled sensor to actuate the valve to open an close the exhaust as needed.
but since i never did this before, i feel kinda stuck.

has anyone experience in building something like that?

what i also thought was modifying a "npp in a box" with mild to wild, to fit my needs. is this viable?

id love to hear your ideas!

SScylla · 12-17-2021, 01:41 PM

i found these pics about the npp control.

i feel like i am missing something. it shouldnt be hard to figure it out but i cant think of a good idea how to get to what i want.

SScylla · 12-17-2021, 01:58 PM

what i thought about so far:

i need the car to be quiet from start, even if *I* dont sit in the car to start it (see if 5-oh is pulling me over, they are going to test if my car is too loud by doing tests by themselves. so i cant hit a "quiet" switch) OR if i dont want to wake up neighbors or whatever.

so: i thought about putting a generic 12V vacuum pump somewhere in the trunk, which will suck air out of the vacuum lines from the moment you click "ignition" with the key.

then a Tank will store said vaccum.

a RPM controlled switch will determine whether or not the valves can be open or closed.

lets say our window to close is from 3500 to 4000 rpm.
so i need a 2 stage switch, 1st stage will send a signal to close, the 2nd stage a signal to open up again.

https://www.amazon.com/NOS-15982NOS-.../dp/B005AU6TZ0

something like that should work just fine.

then i need an electronically operated solenoid, which opens or closes a 5/2 way valve.

the valve knows "suck air out of exhaust flaps" and "let air in" aka "closed" and "open".

then i need to hook up vacuum lines from the tank over the 5/2 way valve to the exhaust.

but like i said earlier. i feel like this might not work somehow and i cant put my finger on it.
i never hooked up a rpm switch to anything so far, even though i work as a mechanic in germany (we dont do these shenanigans here lol)

can someone give me some input on how to achieve my goal here?
thanks in advance!!

SScylla · 12-20-2021, 01:41 PM

is there really nobody on this forum who has any idea how to make this exhaust happen?

SScylla · 12-25-2021, 08:10 AM

love supportive forums

WspoonSS · 12-25-2021, 09:49 PM

It’s hard to say what the level of the stock NPP is at those specific speeds. I will say that many people have swapped the NPP to non-NPP cars

CamaroDreams76 · 12-26-2021, 12:53 AM

I would be surprised that stock NPP with headers would achieve what you are looking for. Meaning I dont think the NPP exhaust will be at a max of 76db at 3750.

NPP in a box with a mild2wild switch or a Forza remote may be your best bet.

Stock NPP is open during start up and idle (which a forza 3 way remote, you can have the valves shut on start up by press of a button) from 3,000rpm-4000rpm under light load the valves close. Then over 4k and anything with heavy throttle input its open.

The forza 3 way remote has the npp operate like stock, always open or always closed. Im not very techy and once wiring and sensors and all that bs is tossed in, above my expertise.

This is the closest thing I KNOW OF what you are looking for.
https://forzacomponenti.com/modelb6.html

12-17-2021, 01:37 PM	#1
SScylla Drives: Camaro SS (2SS/RS Conv. L99) Join Date: Sep 2021 Location: Germany, Bavaria Posts: 12	Custom built NPP Setup for a 2011 SS car hi guys, i was doing some brainstorming about my car. i live in germany and we have kinda strict exhaust laws, or not strict but oddly specific. to cut to the chase: my car can be as loud as it wants, but: it has to have a maximum of 76decibel at 50-70 kph (30ish mph to 40ish) and it has to be quiet with a max of 76 decibel at 3750 rpm. to achieve that, i thought about controlling the valves in these parameters of a NPP exhaust because noone will build such an exhaust in germany afik. lets say i use the stock vaccum lines and an accumulator tank to store vacuum like the zl1 does. then i can hook that up to a 5/2way valve to control the flow of vacuum. from open to close and open up again if needed. i could also use a rpm controlled sensor to actuate the valve to open an close the exhaust as needed. but since i never did this before, i feel kinda stuck. has anyone experience in building something like that? what i also thought was modifying a "npp in a box" with mild to wild, to fit my needs. is this viable? id love to hear your ideas! __________________ 2011 2SS/RS L99 Black OEM ZL1 Front Fascia BMR Motor Mount Solid Polyurethane Bushing BMR Differential Mount Polyurethane Bushing CN Cobra Braided Steel Brake Lines OEM Dual Mode Exhaust NPP OEM Z/28 CAI CN Cobra 1 7/8" Longtubes CN Cobra 200 Cell CAT's OEM Ported Throttlebody 102mm FAST LSx R 102mm Intake Manifold L99 to LS3 Conversion (Except Camshaft) OEM Ported Heads Tuned by CCRP / Cool Chevy Race Parts, Graz, Austria

12-17-2021, 01:41 PM	#2
SScylla Drives: Camaro SS (2SS/RS Conv. L99) Join Date: Sep 2021 Location: Germany, Bavaria Posts: 12	i found these pics about the npp control. i feel like i am missing something. it shouldnt be hard to figure it out but i cant think of a good idea how to get to what i want. Attached Images __________________ 2011 2SS/RS L99 Black OEM ZL1 Front Fascia BMR Motor Mount Solid Polyurethane Bushing BMR Differential Mount Polyurethane Bushing CN Cobra Braided Steel Brake Lines OEM Dual Mode Exhaust NPP OEM Z/28 CAI CN Cobra 1 7/8" Longtubes CN Cobra 200 Cell CAT's OEM Ported Throttlebody 102mm FAST LSx R 102mm Intake Manifold L99 to LS3 Conversion (Except Camshaft) OEM Ported Heads Tuned by CCRP / Cool Chevy Race Parts, Graz, Austria

12-17-2021, 01:58 PM	#3
SScylla Drives: Camaro SS (2SS/RS Conv. L99) Join Date: Sep 2021 Location: Germany, Bavaria Posts: 12	what i thought about so far: i need the car to be quiet from start, even if I dont sit in the car to start it (see if 5-oh is pulling me over, they are going to test if my car is too loud by doing tests by themselves. so i cant hit a "quiet" switch) OR if i dont want to wake up neighbors or whatever. so: i thought about putting a generic 12V vacuum pump somewhere in the trunk, which will suck air out of the vacuum lines from the moment you click "ignition" with the key. then a Tank will store said vaccum. a RPM controlled switch will determine whether or not the valves can be open or closed. lets say our window to close is from 3500 to 4000 rpm. so i need a 2 stage switch, 1st stage will send a signal to close, the 2nd stage a signal to open up again. https://www.amazon.com/NOS-15982NOS-.../dp/B005AU6TZ0 something like that should work just fine. then i need an electronically operated solenoid, which opens or closes a 5/2 way valve. the valve knows "suck air out of exhaust flaps" and "let air in" aka "closed" and "open". then i need to hook up vacuum lines from the tank over the 5/2 way valve to the exhaust. but like i said earlier. i feel like this might not work somehow and i cant put my finger on it. i never hooked up a rpm switch to anything so far, even though i work as a mechanic in germany (we dont do these shenanigans here lol) can someone give me some input on how to achieve my goal here? thanks in advance!! __________________ 2011 2SS/RS L99 Black OEM ZL1 Front Fascia BMR Motor Mount Solid Polyurethane Bushing BMR Differential Mount Polyurethane Bushing CN Cobra Braided Steel Brake Lines OEM Dual Mode Exhaust NPP OEM Z/28 CAI CN Cobra 1 7/8" Longtubes CN Cobra 200 Cell CAT's OEM Ported Throttlebody 102mm FAST LSx R 102mm Intake Manifold L99 to LS3 Conversion (Except Camshaft) OEM Ported Heads Tuned by CCRP / Cool Chevy Race Parts, Graz, Austria

12-20-2021, 01:41 PM	#4
SScylla Drives: Camaro SS (2SS/RS Conv. L99) Join Date: Sep 2021 Location: Germany, Bavaria Posts: 12	is there really nobody on this forum who has any idea how to make this exhaust happen? __________________ 2011 2SS/RS L99 Black OEM ZL1 Front Fascia BMR Motor Mount Solid Polyurethane Bushing BMR Differential Mount Polyurethane Bushing CN Cobra Braided Steel Brake Lines OEM Dual Mode Exhaust NPP OEM Z/28 CAI CN Cobra 1 7/8" Longtubes CN Cobra 200 Cell CAT's OEM Ported Throttlebody 102mm FAST LSx R 102mm Intake Manifold L99 to LS3 Conversion (Except Camshaft) OEM Ported Heads Tuned by CCRP / Cool Chevy Race Parts, Graz, Austria

12-25-2021, 08:10 AM	#5
SScylla Drives: Camaro SS (2SS/RS Conv. L99) Join Date: Sep 2021 Location: Germany, Bavaria Posts: 12	love supportive forums __________________ 2011 2SS/RS L99 Black OEM ZL1 Front Fascia BMR Motor Mount Solid Polyurethane Bushing BMR Differential Mount Polyurethane Bushing CN Cobra Braided Steel Brake Lines OEM Dual Mode Exhaust NPP OEM Z/28 CAI CN Cobra 1 7/8" Longtubes CN Cobra 200 Cell CAT's OEM Ported Throttlebody 102mm FAST LSx R 102mm Intake Manifold L99 to LS3 Conversion (Except Camshaft) OEM Ported Heads Tuned by CCRP / Cool Chevy Race Parts, Graz, Austria

12-25-2021, 09:49 PM	#6
WspoonSS Drives: 2010 Chevy Camaro 2SS Join Date: Mar 2020 Location: California Posts: 36	It’s hard to say what the level of the stock NPP is at those specific speeds. I will say that many people have swapped the NPP to non-NPP cars __________________ 2010 2SS w/ Magnaflow 2.5 muffler, CAI Intake, Stainless Power LT headers, e85 Custom Tune, vararam power wedge, Vararam Ported TB, BMR rear sway bar, BC Racing coilovers.

12-26-2021, 12:53 AM	#7
CamaroDreams76 Tri-County Camaro SWFL Drives: 2013 IOM 2SS/RS/1LE Join Date: Apr 2013 Location: South West FL Posts: 3,079 View My Garage	I would be surprised that stock NPP with headers would achieve what you are looking for. Meaning I dont think the NPP exhaust will be at a max of 76db at 3750. NPP in a box with a mild2wild switch or a Forza remote may be your best bet. Stock NPP is open during start up and idle (which a forza 3 way remote, you can have the valves shut on start up by press of a button) from 3,000rpm-4000rpm under light load the valves close. Then over 4k and anything with heavy throttle input its open. The forza 3 way remote has the npp operate like stock, always open or always closed. Im not very techy and once wiring and sensors and all that bs is tossed in, above my expertise. This is the closest thing I KNOW OF what you are looking for. https://forzacomponenti.com/modelb6.html __________________ Just bolt ons........ https://www.camaro5.com/forums/showthread.php?t=343023 Last edited by CamaroDreams76; 12-26-2021 at 02:37 AM.