Automatic Dual Mode Muffler = loud when u want it loud

[DJJordache]

Dual Mode Muffler


All of us like the heavy power sound from a good running Jeep engine and the factory grocery getter sound does not get it.
I have tried MANY exhaust setups on mine: glass pack, Flow 40, Delta flow 40, and straight pipe, with my full 2.5 inch exhaust system from the engine back, route for the power-house sound and, for a while, it sounded good.
The only problem is, after a while the sound tends to drone from the back glass, and the constant loud exhaust, becomes a detriment to conversation on long highway hauls. There had to be a better way.

Off to the Summit catalog, which of course I keep in the “Library”. What do I find, but a muffler called the Warlock in all sizes and inlet selections. The interesting thing about it is that it has three ports. Inlet, outlet (Which is offset) and a bolt-in removable plug for straight through exhaust (Read Sound) flow.
Now, getting under the Grand to remove and install, this plug, is not in the cards for every day driving. What if I could get this port to open from the inside of the cab while driving, or better yet, if I want to get it automatic for power, but quieter for normal driving.
There are a number of electric cutouts on the market, but they use stepper motors for a controlled opening amount. I wanted automatic open and close, and these systems will not stand continuous signal. They cannot open and close via the use of a micro switch, which would be more difficult to install anyway. They are also VERY PRICY.
Back in the late 80’s General Motors used a vacuum actuated heat riser valve just outside of the right hand exhaust port on many of the small block V-8’s. This valve was spring open and vacuum closed. If I could use this valve for an automatic bypass, I would be in business.
I bought one of these valves (part number below), although you can find them on, for example a mid 80’s Suburban in the junkyard. I connected it to the intake manifold of the Grand with a 10 foot hose and off for a drive. Within about one second of start up, the valve closes. Cruising speed vacuum is around 10-16” vacuum. Start to accelerate and the vacuum drops fast to 0. If the intake manifold vacuum drops at or below 5”, the valve begins to open and is fully open at around 2.5”. This will work!!!
One call to Summit Racing for one 2.5” Warlock (BIG-50522flt) center inlet and center outlet muffler and a 2.5” “Y” pipe (SUM-G4821) and a short piece of 2.5” pipe and we are off.

This is the plug that comes with the muffler to block off the center through flow passage. Originally, you need to unbolt and remove this for unrestricted exhaust flow. It will now be discarded.


Here is the heat riser valve (Oreilly auto part number Murry #150) used to create the automatic bypass effect. Spring open and vacuum closed. Begins to open around 5” vacuum. It is not a sealed closed valve, in the closed position, but enough to do the job.

The Y pipe that comes from the Summit, come with extra flange adapters, You will need a short length of 2.5” exhaust pipe and weld one of these flanges on to it and the pipe modified to return to the Y pipe. This is the standard muffler outlet to the tail pipe.

Here it is being mocked up prior to welding to get the proper angle. I wanted to be able to remove the system, if maintenance were required. Note the second flange adapter mocked up on the straight part of the Y pipe. The heat riser valve has a tapered end that will seal directly into the muffler outlet. Make sure that there are no burrs in the outlet pipe and there will be no leak after you tighten the three bolts. You do need a gasket for between the y pipe to heat riser valve and the muffler outlet to the y pipe. These come with the Y pipe.

Here is a picture of the valve in the closed position. This occurs at full vacuum down to 5”, where it begins to open.

Here, the valve open with no vacuum

Close up of the installed vacuum valve installed and bolted together. No gasket is needed as the tapered seat goes to the muffler. Just make sure the inlet hole has no burrs and it will seal. You need a gasket between the valve and the y pipe and some small grinding of the holes for alignment may be necessary. I used 3/8” bolts and lock washers.


Here is the final installation. Note, I have heard that the Warlock is prone to rusting. I sanded off the original paint and repainted it and the installation, less the valve with the best high heat paint I could find. The original paint came off WAAAYYY too easy, so I would really recommend this extra step.

Final Installation

older pic before I got the rear adjustable arms and welded the exhaust instead of the clamps.
Make sure the vacuum valve is pointed in the up position to avoid damage.

Just bolt, clamp or weld the system into the exhaust pipes as you would a normal muffler and hook up a vacuum line to any port on the intake manifold and you are in business. The Grand now has over 10,000 miles on this set up and it works perfectly. Reasonably quiet for normal driving, but “aggressive” straight through exhaust when you get on it

[KeepItCrunk]

well, i would say thats sick. But its not, because your ass just found a way to make me waste another weekend and paycheck on my jeep.... im just gonna stop goin on this site, then i'll stop getting ideas... hahaha. but anyways, i was gonna do this with that mechanical dump valve from JC whitney, but they looked really hobbly. the DHM i beleive? electric one was really sick... but like 200 bucks or something... i definately respect u figurin this out. U think theres any way you could like, get a sound clip link or something like that up on here? thanks man. later days

[ILikeMud]

Sound clip would be cool.
How'd you like the glass pack? I think that's my next set up.

[DJJordache]

Sound clip would be cool.
How'd you like the glass pack? I think that's my next set up.

here is a "ok" sound clip it does sound better in person and I had to downsize the video some to put on the internet http://media.putfile.com/ZJ-before-intake-swap-dyno
I had a Dynomax Race Bullet glass pack which sounded way better than the cherry bomb glass pack I had on it before. The cherry bomb was kinda ricey! I only had it on there for like a month and went to the dynomax race bullet which sounded alot deeper and more "pipey"
when you watch this dyno run listen real close around 3000 RPM where the engine gets louder when he gets on it at about 2600-3000 and RIGHT after that at about 3000-3400jump it gets louder again, the second one is the muffler opening up
sorry the audio portion is kinda crappy the mics they put in cameras kinda suck for things that are loud and they get all crackly...

well, i would say thats sick. But its not, because your ass just found a way to make me waste another weekend and paycheck on my jeep.... im just gonna stop goin on this site, then i'll stop getting ideas... hahaha. but anyways, i was gonna do this with that mechanical dump valve from JC whitney, but they looked really hobbly.

I thought about the push pull cable thing from JC but it was only 2.25 and cast iron.... I REALLY understand the part about getting ideas! If I never had gotten on the forums my Jeep wouldn't feel inadequit and need CONSTANT upgrades, JEEP= Just Empty Every Pocket now I need more and more, looking at long arms, axle upgrades, brake upgrades, and more because of getting ideas off the internet

[KeepItCrunk]

Amen to that dude, hahaha

[AndrewB]

This is a very cool setup.

Have you tried pinching the line closed after startup to see if the hose will hold the vaccum? This way a small valve could be sliced in to keep the flap closed.

Any one know if any vehicule had a heat riser in a 3 inch size?

[DJJordache]

Have you tried pinching the line closed after startup to see if the hose will hold the vaccum? This way a small valve could be sliced in to keep the flap closed.
Any one know if any vehicule had a heat riser in a 3 inch size?

It should hold vacuum no problem, but if you thinking about being able to hold it closed no matter what the intake vacuum is, I'd just make like a 3 way valve setup on the line to it so that one way would be normal like my setup and the other way would have a 1 way check valve that once it built vacuum to hold it closed it would stay closed.

I have not seen a 3" one but I'm pretty sure they exist, I know Thorley used to make some vacuum ones that were 3" but I think they discontinued them, just go up to Oreilly's auto and they have their big green book catalogs to look stuff up in without knowing the vehicle aplication, is how I got mine, but it was PRICEY! if you can find out the aplication and see if you can find it in a junkyard

I did a little lookin around and thorley only lists the 2.5" one. I think they make the heat actuated(cheap) one up to 3" so you might have to modify a heat one and make it vacuum(junkyard) to get one 3", would probably be cheaper this way too!

[faststang1]

Wheres The Vid??????

[ILikeMud]

Holy old thread!

[DJJordache]

Holy old thread!

x2 almost 2 years old! I'll see if I can find the vid and reup it. Actually I don't even run this muffler anymore since I could not fit it in there with the longarms. So for now I'm using a magnaflow, until I get around to building version 2.0 of this

[macka]

why not use a butterfly valve and control it via a cable? and have the cutout well ahead of the muffler with a pipe running out the back? It doesn't have to be a fancy butterfly and there are companies that make them all metal for hot gas/liquid apps.

[zsimp]

You could even have the same idea, but instead of having it go through the muffler, just have it open to the atmosphere. I think I like that idea.. might have to try it out.

[Ds4x4]

Holy old thread!

every two years eh?

captains call or captains choice witch ever you want to call it..

[Brodon]

well, i would say thats sick. But its not, because your ass just found a way to make me waste another weekend and paycheck on my jeep.... im just gonna stop goin on this site, then i'll stop getting ideas... hahaha. but anyways, i was gonna do this with that mechanical dump valve from JC whitney, but they looked really hobbly. the DHM i beleive? electric one was really sick... but like 200 bucks or something... i definately respect u figurin this out.

[cowboy63b]

HA, now its 4 years!