Automatic NPP Actuator for $25!
Le Mans Master
Joined: Aug 1999
Posts: 8,827
Likes: 10
check valve might be a good idea. those diaphrams werent designed to see positive pressure
You're probably right however I've had positive pressure on a couple of my C6Z's for many many thousands of miles and never had a problem. Have you ever seen a malfunction because of pressure?
Le Mans Master
Joined: Oct 2003
Posts: 8,863
Likes: 86
From: PA
St. Jude Donor '08
Le Mans Master
Joined: Oct 2003
Posts: 8,863
Likes: 86
From: PA
St. Jude Donor '08
hey ed look at this site....they have almost everything
http://www.mcmaster.com/#about-check-valves/=bjug4
http://www.mcmaster.com/#about-check-valves/=bjug4
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 6,149
Likes: 11
From: Greater Detroit Metro MI, when I'm not travelling.
Most importantly, a check valve will prevent the system from working at all
...
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 6,149
Likes: 11
From: Greater Detroit Metro MI, when I'm not travelling.
It is to prevent two way flow of a liquid or a gas. A&As FI kit adds one for that reason. Your car also has one on the brake booster so it is aways under vacuum. Adding one to the NPP actuator would make it either always closed or always open... Not very useful 
Le Mans Master
Joined: Oct 2003
Posts: 8,863
Likes: 86
From: PA
St. Jude Donor '08
cool.....gotta part # or a price...i need one!!
please explain why it wont work.....insurance saleman here not an engineer. just a dumby here
Last edited by NICK YOSKIN; Jan 29, 2009 at 12:11 AM.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 6,149
Likes: 11
From: Greater Detroit Metro MI, when I'm not travelling.
A check valve is a one way valve. So, if you put it towards the mufflers, it will allow boost through when you get on the gas, opening the mufflers, but then when you get off the gas, it will close; the mufflers will never see vacuum so they will never close.
Reverse the check valve and the reverse happens; it is open under idle and decel, keeping the muffler butterflies closed, but the second you get on the gas he check valve closes so the mufflers never see anything above vacuum and thus they never open.
Not sure where you can get those actuators... Gene Culey from GMPartswarehouse can help you out though.
Last edited by PowerLabs; Jan 30, 2009 at 11:51 AM.
Melting Slicks
Joined: May 2004
Posts: 3,017
Likes: 2
Well, think about it a little bit: The NPP Mufflers open when they see vacuum, and they close when they see no vacuum (atmospheric pressure or boost).
A check valve is a one way valve. So, if you put it towards the mufflers, it will allow boost through when you get on the gas, opening the mufflers, but then when you get off the gas, it will close; the mufflers will never see vacuum so they will never close.
Reverse the check valve and the reverse happens; it is open under idle and decel, keeping the muffler butterflies closed, but the second you get on the gas he check valve closes so the mufflers never see anything above vacuum and thus they never open.
Not sure where you can get those actuators... Gene Culey from GMPartswarehouse can help you out though.
A check valve is a one way valve. So, if you put it towards the mufflers, it will allow boost through when you get on the gas, opening the mufflers, but then when you get off the gas, it will close; the mufflers will never see vacuum so they will never close.
Reverse the check valve and the reverse happens; it is open under idle and decel, keeping the muffler butterflies closed, but the second you get on the gas he check valve closes so the mufflers never see anything above vacuum and thus they never open.
Not sure where you can get those actuators... Gene Culey from GMPartswarehouse can help you out though.
Sam, you got it backward..Mufflers are open at startup..ie no vacuum, and close when vacuum is present. Thanks for the writeup and pictures..I'm plumbing mine up in the next couple of weeks..
Last edited by nwc6; Jan 29, 2009 at 10:37 PM.
