NPP exhaust valves on my SW 3" pipe set - ZR-1 Net Registry Forums

mike100 · 10-24-2013

I liked the extra top end power on my recently purchased SW 3" Cat-back, but lets not even try to be diplomatic- it's pretty much loud enough to piss off your neighbors and give you a headache on a long trip.

So I got some C6-Z06 mufflers with the NPP exhaust flapper valves (vacuum actuated).

Note that the inside pipes are the loud, high flow straight thru section. This will be blocked during cruise conditions.

Hacked them off to put them on my loud-*** SW mufflers.

Working out the fit- had to rotate them a touch to fit the vacuum can.
Also the diaphragm comes loose and you can reposition it so the vacuum nipple points in any direction.

mike100 · 10-24-2013

Got the staggered tip the same on both sides- sort of follows the fascia curve.

mike100 · 10-24-2013

So I finally received the adjustable vacuum switch. When the vacuum controlled secondary throttle is activated on the LT5, so is my loud valve. I set it to 12" of vacuum (12 in Hg).

The switch powers a junkyard EGR vacuum solenoid. This couples the vacuum to the muffler valves. It either connects the vacuum to the valve, or vents the vacuum to the atmosphere thru the little foam filter on the 3rd port. It never has a vacuum leak on the source end. Perfect $8 solution (I should have pocketed it but I was feeling honest). The vacuum source is the nearby vacuum ball used for the a/c and air injection diverter valve. The 12v was easy too- I tapped into the under hood lamps which of course aren't even connected on my car anyhow.

This is actually a second MAP sensor just to monitor the secondary throttle system. I 'T'-ed into it. Vacuum here means all 16 runners and injectors are working on the LT5 and it was a simple idea to switch the NPP valve off of this computer controlled load function.

Here it is idling- the loud section of the muffler is blocked off (left pipe). Will try to get a video on Saturday.

mike100 · 10-24-2013

Just in case you missed the picture of the SW muff. One pipe is straight-thru, the other actually muffles:

XfireZ51 · 10-25-2013

So whaddya think?

mike100 · 10-25-2013

Quote:

Originally Posted by XfireZ51

So whaddya think?

It's great! Bit of a treasure hunt to get the Z06 mufflers I found. I could leave it well enough alone, but I think I can get faster opening and closing if I run a 2nd vac solenoid and have a dedicated feed to each actuator. Bleed down would have twice the vent capacity.

I do rather like lugging the revs a tad and not droning (at all).

Paul Workman · 10-25-2013

Really interesting setup Mike!

I think I have the jist of what you've done, but pls allow me summarize what I think I understand, and then maybe you can clear up where I "lost your trail".

The adjustable vacuum switch receives vacuum from the "T" connection that also feeds vacuum to the MAP (under the ECM on a 1900 Z). At or below 12" Hg, the switch closes, activating the vacuum solenoid.

Normally, this solenoid connects plenum vacuum to the NPPs - keeping them closed. But, when plenum vacuum drops below 12" Hg, the vacuum solenoid receives its signal and "vents" the vacuum to the atmosphere (through the foam filter), thus relaxing the NPP diaphragms and thus opening the exhaust gates.

Now, if not already, is where I get a little

...

You referenced a second MAP, and dedicated vacuum solenoids for each NPP valve. I get the reasoning for the dual system - decreasing bleed time - but I'm missing a link here...

It looks like the vacuum solenoid (pictured) would directly operate the NPPs. But, it is this additional MAP you mentioned, and the electric/vacuum circuitry at the NPP end that has me

. I gather the system as it is now is a "work in progress", is it? By that, I mean the NPP end of the setup is yet to be upgraded for individual operation???

As you can see, Mike, I wandered off the path somewhere...

-=Jeff=- · 10-25-2013

Mike,

you needed the tips as well correct? mind if I ask how much you paid for the NPP mufflers?

I have seen the valves themselves on eBay for about $100 each for new ones

GOLDCYLON · 10-25-2013

Nice thread and a great solution. Dom did you do this electronically or via vacuum like Mike? GC

XfireZ51 · 10-25-2013

Quote:

Originally Posted by GOLDCYLON

Nice thread and a great solution. Dom did you do this electronically or via vacuum like Mike? GC

Mine are connected via what was the vacuum line for the canister and plugged into driver's side plenum port. The one that was previously used for the secondaries. No switch so the NPP valves open progressively like vacuum secondaries on a Quadrajet carb. Sounds a bit like it too. BBBWWWWAAAAAAAAAA! Pretty sure Pete, Al, and BobGs set ups are similar.
Pete has his valves grafted onto B+B tips, Bob and I use the Z06 tips.

Paul,

Were u working on another source for the valves? It is an Easter Egg hunt to find someone who'll cut the tips off and sell for a reasonable price.

10-24-2013	#1
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,786	NPP exhaust valves on my SW 3" pipe set I liked the extra top end power on my recently purchased SW 3" Cat-back, but lets not even try to be diplomatic- it's pretty much loud enough to piss off your neighbors and give you a headache on a long trip. So I got some C6-Z06 mufflers with the NPP exhaust flapper valves (vacuum actuated). Note that the inside pipes are the loud, high flow straight thru section. This will be blocked during cruise conditions. Hacked them off to put them on my loud-*** SW mufflers. Working out the fit- had to rotate them a touch to fit the vacuum can. Also the diaphragm comes loose and you can reposition it so the vacuum nipple points in any direction. Last edited by mike100; 10-25-2013 at 12:03 AM.

10-24-2013	#2
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,786	Re: NPP exhaust valves on my SW 3" pipe set Got the staggered tip the same on both sides- sort of follows the fascia curve.

10-24-2013	#3
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,786	Re: NPP exhaust valves on my SW 3" pipe set So I finally received the adjustable vacuum switch. When the vacuum controlled secondary throttle is activated on the LT5, so is my loud valve. I set it to 12" of vacuum (12 in Hg). The switch powers a junkyard EGR vacuum solenoid. This couples the vacuum to the muffler valves. It either connects the vacuum to the valve, or vents the vacuum to the atmosphere thru the little foam filter on the 3rd port. It never has a vacuum leak on the source end. Perfect $8 solution (I should have pocketed it but I was feeling honest). The vacuum source is the nearby vacuum ball used for the a/c and air injection diverter valve. The 12v was easy too- I tapped into the under hood lamps which of course aren't even connected on my car anyhow. This is actually a second MAP sensor just to monitor the secondary throttle system. I 'T'-ed into it. Vacuum here means all 16 runners and injectors are working on the LT5 and it was a simple idea to switch the NPP valve off of this computer controlled load function. Here it is idling- the loud section of the muffler is blocked off (left pipe). Will try to get a video on Saturday. Last edited by mike100; 10-24-2013 at 11:46 PM.

10-24-2013	#4
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,786	Re: NPP exhaust valves on my SW 3" pipe set Just in case you missed the picture of the SW muff. One pipe is straight-thru, the other actually muffles: Last edited by mike100; 10-24-2013 at 11:51 PM.

10-25-2013	#5
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,686	Re: NPP exhaust valves on my SW 3" pipe set So whaddya think?

10-25-2013	#7
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,466	Re: NPP exhaust valves on my SW 3" pipe set Really interesting setup Mike! I think I have the jist of what you've done, but pls allow me summarize what I think I understand, and then maybe you can clear up where I "lost your trail". The adjustable vacuum switch receives vacuum from the "T" connection that also feeds vacuum to the MAP (under the ECM on a 1900 Z). At or below 12" Hg, the switch closes, activating the vacuum solenoid. Normally, this solenoid connects plenum vacuum to the NPPs - keeping them closed. But, when plenum vacuum drops below 12" Hg, the vacuum solenoid receives its signal and "vents" the vacuum to the atmosphere (through the foam filter), thus relaxing the NPP diaphragms and thus opening the exhaust gates. Now, if not already, is where I get a little... You referenced a second MAP, and dedicated vacuum solenoids for each NPP valve. I get the reasoning for the dual system - decreasing bleed time - but I'm missing a link here... It looks like the vacuum solenoid (pictured) would directly operate the NPPs. But, it is this additional MAP you mentioned, and the electric/vacuum circuitry at the NPP end that has me . I gather the system as it is now is a "work in progress", is it? By that, I mean the NPP end of the setup is yet to be upgraded for individual operation??? As you can see, Mike, I wandered off the path somewhere...

10-25-2013	#8
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,161	Re: NPP exhaust valves on my SW 3" pipe set Mike, you needed the tips as well correct? mind if I ask how much you paid for the NPP mufflers? I have seen the valves themselves on eBay for about $100 each for new ones __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Shelby Series 1 - Wilwood Brakes Custom Interior NCM Lifetime Member #978

10-25-2013	#9
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,119	Re: NPP exhaust valves on my SW 3" pipe set Nice thread and a great solution. Dom did you do this electronically or via vacuum like Mike? GC __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V