Chevy Exhaust Back Pressure Actuated Valve

[DRACO A5OG]

Anyone try this hack?

Taking a Chevy Truck's exhaust valve actuated by BACK PRESSURE to a dual out system?

Yes, crazy I know, but I did not know this even existed until today. It supposed to keep noise levels stock until WOT or high enough back pressure.

I always thought it had to be rigged to the Tach or Vacuum line.

Just havin fun

[DRACO A5OG]

So I was pondering, do I really want to cut up the rear valances or make her a sleeper and put dual out to the side like the 930 stock???

Hmmm...

Option #1


Sleeper no body mods

Option #2


Cutting of rear and side lower valance :-(

[rnln]

What is "Chevy Truck's exhaust valve actuated by BACK PRESSURE". What does it do Draco?
That red 911 exhaust looks just like mine.

[Driven97]

The DynoMax VT series has a sprung valve inside. No idea if it works or not, or for how long.



I also think a few '00s Nissans had similar passively variable exhausts, so it passed something for a production car.

If you want something a little more active, there's both electronic (aka you can hit a switch and change sound, or hook it up to a WOT switch) or vacuum actuated ones. Just google exhaust cutout.

[J0hnny]

What are you trying to accomplish with this?

This flap is in the GMTs and Camaros to alleviate the booming noise when the V8 enters in AFM mode (V4), the spring is tuned to work at a certain RPM level, and it works in conjunction with the muffler, if you put this valve in a stock system it is just a dead weight.

It is not a bypass like the actuated butterfly valves, it is more of a pressure damper.

[DRACO A5OG]

Originally Posted by Driven97

The DynoMax VT series has a sprung valve inside. No idea if it works or not, or for how long.



I also think a few '00s Nissans had similar passively variable exhausts, so it passed something for a production car.

If you want something a little more active, there's both electronic (aka you can hit a switch and change sound, or hook it up to a WOT switch) or vacuum actuated ones. Just google exhaust cutout.

Oh yeah, well aware of those. I never knew there was a Back Pressure Actuated Valves.

I like the fact it requires no addition of a vacuum line or electronics.

As far my goal, well really did not think about it but I really liked my buddy's GT3 WOT sound on the freeway. CRRRAZZZY sound

Muffler shop stated the Chevy EBPV is 2.75" OD. He looked at my car and I have couple of install options. Kinda excited about this :-D

[DRACO A5OG]

I was thinking about the spring, maybe it can be swapped for less tension to tune it to the RPMs I want it open to???

[Reiver]

Quiet riot......search it.

[DRACO A5OG]

LOL



Gatling Gun, rat tat tat tat. Just need lazers, guy chuckling at the end, too funny.

[Brian 162]

My Z06 has it. When I bought the car the system wasn't working so all 4 tailpipes were open (there's 1 valve per muffler). The exhaust drone was 5 times worse than my dual out muffler on my old SC.
The system runs off engine vacuum. If there's no vacuum the valve is wide open. There's a circuit board that allows vacuum to close the valve depending on throttle input.
Your idea is pretty good if you could apply it to a 911.
Some speed shops sell an electric valve that is off/on that's controlled by a simple switch.

[kjchristopher]

Originally Posted by DRACO A5OG

I never knew there was a Back Pressure Actuated Valves.

You mean a metal flap with a spring to keep it closed?

Here is a picture of a different form of "Back Pressure Actuated Valve:



and a style commonly seen on bull dozers:



And one that was in my 1968 mopar. This one uses a bi-metal spring so it stays open when hot. It is used as a diverter to heat up the manifold, and would open up as your engine heated up. But until that point, it also opened when you put your foot into it.



And here is one that goes in a boat:

[DRACO A5OG]

Wow, can't believe I missed these. Interesting.