Dominic Sorresso

NPP Exhaust Control Valves help control resonance without the weight and backpressure of a resonator. However the use of engine vacuum can also cause the valves to open during low vacuum or high MAP conditions. Typically, this happens on inclines causing the valves to crack open increasing resonance. I recently had the opportunity to find an NPP Retrofit kit by Nakid Parts. However, in trying to install it, it didn't work well or not at all. Everything checked out and it did work when using a brake bleeder as a vacuum source. When applying engine vacuum however the exhaust control valves remained in whatever position they were in with engine start. Everything checked out. NakidParts checked the unit and found it to operate properly. They stated that they had 800 units in operation including one for Jay Leno. Maybe it's an issue w the LT-5 v an LS-3 or LS-7.
Reviewing the electrical, pneumatic circuits there was no reason why it shouldn't work. But it just didn't. As Sherlock Holmes would say to Watson,

'How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?'

It's now clear the solenoid used w the NPP in a Box Retrofit kit has an issue, at least, w LT-5 engine vacuum. mike100 has done his own NPP control using a GM EGR solenoid. I decided to try this solenoid in place of the one used for NIAB retrofit.
So here's a video showing the operation of the NPP retrofit BUT using a GM EGR SOLENOID in place of the stock NIAB solenoid.

mike100

I'm not surprised the universal GM style solenoid worked, but definitely intrigued by the mysterious malfunction of the one in the kit. It is possible just that one was somehow defective and the spring is collapsed and can't fight the engine vacuum???

Dominic Sorresso

Mike,

I bought one of those solenoids directly from Clippard. Same result. I am leaning towards the solenoid being marginal in this particular application. Maybe ok for c6, but not LT-5 w cams. Now I am trying to find male mini-spades so I can connect the EGR solenoid w the fob circuit. The spade is 3mm wide.

Paul Workman

Dom,

Tri State Electronics in Arlington Hts. might have what you're looking for. It is very near Wayne's Pizza (which you're familiar with).

-=Jeff=-

I don't see that preview anywhere.. only the Jan edition

mike100

Ahh, that's right- now I remember...that would have been the first logical conclusion that an individual unit was defective. I suppose it has something to do with the vent being through the center of the device and not like the GM style. Still plenty of LS engines get cammed, but then again, a lot of those were NPP from the factory.

Dominic Sorresso

Mike,

That's true except the kit I installed is billed as a "retrofit" kit and
as NPP in a Box. Everything you need all in one unit. So it does not depend on having any other NPP components other than the mufflers. That's why I thought it would work for us. I am tempted to reinstall the Clippard solenoid and re-confirm my results.

Paul Workman

My BAD! I confused the Jan issue with the next issue currently being prepped for publication in the next couple weeks or so!

P.

Dominic Sorresso

Mike,

Maybe I could send you one of the solenoids and have you take a look.

mike100

If you still have my mailing address- go ahead. my circuit is in the engine bay and easily accessible and I could test it fast.

Dominic Sorresso

Mike,

PM me ur addy. Don't think I have it.

Dominic

89'Bowtie

That is cool. Sounds good too. I've used those GM solonoid for allot or random projecet needing vacuum control, they can be pretty versatile if used right.

I wanted to try NPP on my C4, but the cost of the valves and gear got me pretty close to used Corsa setup. I just wanted the resonance gone.

You need something for the sound waves to bounce off (closed valve/butterfly) as you've done to let them cancel out and reduce or eliminate the resonance.

Dominic Sorresso

89,

The NPP valves not only reduce the resonance but eliminate the weight of a resonator as is found on the Corsa. I can also use a 3" exhaust and basically straight thru muffs like the DynoMax UltraFlo. The best of both worlds as these are the same reasons the valves are found OEM on the Z06. IMO, I think it sounds better than the Corsa also.

89'Bowtie

You're right that centre resonator does have some weight. The corsa isn't the best sounding, even though I enjoy it, but it's definitely the best off the shelf "kit" resonance killer.

The NPP cars do sound great.

Cool project. Glade it worked out. By the way, I've followed you brake upgrade on you car also. You take on neat projects.

Vic

Dominic Sorresso

ZR-1 is a neat car.

Dominic Sorresso

Have run into a glitch that really has me scratching my head. The M2W remote fob works just fine when the motor is running BUT when the vacuum solenoid and wireless receiver are powered using my little lawn tractor battery as a stand in. However, once I transfer power and ground over to the car BATT and ground, it won't work with engine running. With ignition ON, but no engine start, I can hear the solenoid clicking as I press the fob. Once I start the motor, NADA. Appears that no signal is getting through to the wireless.
At this point, I'm about to give up on the fob and install a ground interrupt switch in the console. I don't see the real value of the fob. It's not like I am going to be walking around the car while it idles and I click the fob on and off.
A toggle switch in the console should work just fine as you drive.
Maybe one of you EE geniuses can come up w a good solution. I may try it just to solve the mystery but otherwise, I've spent way too much time messing w this thing. Altho I definitely want to be able to control the opening and closing of the exhaust valves.

Dominic Sorresso

OK. Decided to forego the fob. However, I have it connected so if I ever figure out what the issue is, I can use the fob as an alternative. Frankly, I don't see myself wanting to close or open the exhaust valves when I am outside of the car with motor running.

Here's my solution. BTW it was idling like that and THEN I realized I had left off the brake booster hose AND the vacuum supply to the Fuel Pressure Regulator. DOH!

Dominic Sorresso

OK. Time to see how the check valve works.

Here's the NPP control installed in rear quarter



And then here's the NPP control working w the check valve in-line. so this will give me a ON/OFF capability depending on which way the console rocker switch is set.