Dynomax VT muffler - worth taking a look

http://www.dynomax.com/images/mufflers/muf_vt.gif

 

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[ame=http://www.youtube.com/watch?v=xQDY3PD7g0w]http://www.youtube.com/watch?v=xQDY3PD7g0w[/ame]

 

 

http://forums.evolutionm.net/evo-engine-turbo-drivetrain/493903-project-valve-technology-muffler.html

 

 

Edit:

Still on the fence about whether to do Two 2.25" ones behind the bumper, or One 3" in the midpipe. Comes down to the spring choice of <4Liters or >4 liters. Many of the turbo guys ranging from 2-3.5L are finding the <4Liter version to be too soft a spring, and opening too early or even during Fast cruising. But the trade is almost certain hampering of boost threshold...

 

I currently have an Autospeed CBE, and I love love love it, but it really ruins the stealth goal I've been pursuing. Cops down here don't always take kindly to 'them thur ricey jap car boys.'

my buddy bought one. sounds like crap imo. best mufflers ive heard (if you can find em) are prodrives. just that right balance imho.

You can do what a friend of mine did years ago.

 

Get a QTP electric cutout, weld it into the middle of your midpipe (or buy 4 flanges and bolt it into the midpipe).

 

Drill a bunch of 1/4" holes in the plate. When you want stealth, close the cutout. When you want loud, open it up. It was kind of neat.

 

Another idea would be to have that flap controlled by a wastegate, much like the exhaust on the 335i.

my buddy bought one. sounds like crap imo. best mufflers ive heard (if you can find em) are prodrives. just that right balance imho.

 

Can you get him to record a quick sound clip? Not much to go on from my perspective since crap could be anything.

 

As a midpipe muffler, the sound can still be augmented with two tailpipe mufflers.

 

Edit: Part of the consideration is I've gone EL headers, so the exhaust has no personality anymore. Even with Autospeed CBE (best sounding ever in my opinion) it just isn't special anymore. So might as well be pragmatic about it.

 

Edit Edit: What car and header type does your friend have?

You can do what a friend of mine did years ago.

 

Get a QTP electric cutout, weld it into the middle of your midpipe (or buy 4 flanges and bolt it into the midpipe).

 

Drill a bunch of 1/4" holes in the plate. When you want stealth, close the cutout. When you want loud, open it up. It was kind of neat.

 

Another idea would be to have that flap controlled by a wastegate, much like the exhaust on the 335i.

 

I'm all for having a really quiet muffler in the midpipe, two straight through perforated in the tailpipe, and an electric cutout to bypass around the midpipe muffler. But the dynomax VT would be a lot easier and cheaper.

I have an autospeed cbe also. I had a borla xr1 welled in place of the resonator. Sounds awesome but it's still on the louder side of stealth.

Can you post a sound clip? Since going EL headers it's no longer "too loud." The XR1 also got a great review from Itsme. How does it sound vs Autospeed resonator? Still as low and rumbly? How much quieter?

sound clip? i wish, i hardly see the guy. sorry. i do know one of his biggest gripes was that the flap rattled but supposedly they made a new improved spring for it.

my buddy bought one. sounds like crap imo. best mufflers ive heard (if you can find em) are prodrives. just that right balance imho.

 

 

I love my Prodrives with my EL headders.

I love my Prodrives with my EL headders.

 

^$$$ taste

http://forums.evolutionm.net/evo-engine-turbo-drivetrain/493903-project-valve-technology-muffler.html

 

This is the LONG Evo thread, and I'm on page 5 out of 23 so far. Good test reviews.

 

There's also a Cobalt SS :lol: thread about the dynomax vt, but it's practically useless so far.

Very excited about this muffler. Trouble is there's NO data on it. Next step is to try to reach the manufacturer.

I might take a look at the stock mufflers on a 335i, and see about using them. They have a very similar valve, but don't completely block air flow when the valve is closed, they simply open up more when you get on it.

 

I'll take some pics if I can get to a pair of them today.

The latest revision of the VT has a bigger gap on the short side of the valve, assumably to alleviate some of the flapper rattling due to idle and low load pulses hitting it and forcing the older version momentarily open. This benefit is perhaps a design side effect of the lower portion of the flap supposedly contacting the muffler inner wall, thus causing the raddle as well. So there is a lack of clarity as to what exactly caused the original defective part rattle and why, but the new version appears to be slightly better either way. I would much prefer a vacuum operated valve as well, but it would have to be affordable, and so far there is no aftermarket support.

Woah, the 335i stuff definitely wont fit. Oh well.

.Talked to a tech rep, who is going to see if the engineers are willing to release any data, if they have any.

 

He said the >4L version would be an awful match to a 2.5L turbo, but he had a lot of trouble getting at why. I suspect he was alluding to the back pressure causing less of a differential over the turbine wheel, causing it to want to spool slower due to less resulting airflow through the original spool range assuming there isn't any restriction in the first place. Either way I would have 90 days to return one, which is bomb ass. Plenty of testing could be done in that time

 

The Evo guys are all about the >4L version because it stays closed even under light acceleration at high speed. It appears only one member, the OP, tested the <4L version, and he did not like it because the valve opened a little at highway cruise. I wonder how different the stock 4G63 cam profile is vs that of the EJ255/7, and what the pulses difference is like, both in stock and EL header flavors.

One thing to consider is that we have two mufflers on larger diameter pipes vs. the EVO single muffler. You might HAVE to use the <4L muffler if you want the plates to open at all, unless you plan on using one in the midpipe, which seems silly to me (you'd lose ground clearance!)

 

I'm sending you a PM.

I don't understand your post here. They use the same spring across the whole <4L line. I don't know enough about physics to comment on the differences of a 2.25" opening earlier or later vs a 3", but my hunch says same amount of energy acting on the valve at same distribution across the valve = same across sizes. Maybe someone with a physics education can comment.

 

Either way my eventual thought is to put two 2.25" VT cans behind the rear bumper, and have that be it for a while. From what I have seen and what I can figure, this is the safest bet. Would it be stiffer or softer opening that one 3" >4L in the midpipe? I don't know, but either would be fine.

 

If anything, a good exhaust will transfer pulse energy that resonates with the valve, so putting the valve a little further from the engine may give the pulses a tiny bit extra amount of dissipation to keep the valves moving more smoothly, no pulsing. Conversely, there will be a tiny bit more volume to fill with back-pressure before the valves pop open, so in that way there might be a tiny response or spool advantage with the 3" one closer to the turbo. But at the lower RPM lower load areas where the valve would be closed, the factors that permit optimal torque production are different than when flowing over 400 g/s at redline. So: I don't know, I don't know, 2.25" x2 is probably the safest bet as long as you have the Y split designed to split exhaust flow evenly. I have seen some where the driver muffler gets more air than the passenger muffler. That would not be so great with this.

Resurrecting this one. Did anyone try this? I have a 2012 LGT that comes with ELH and would consider this.

Resurrecting this one. Did anyone try this? I have a 2012 LGT that comes with ELH and would consider this.

 

Rao did on his LS-swapped BMW, and plenty people have elsewhere. I don't know whether the company fixed the rattle issues that plagued the initial release of these.

 

I am far more interested in re-purposing an OEM design like the Corvette dual mode mufflers, which each run off a vacuum-actuated valve, and an interrupting solenoid. OEM quality, rarely beaten.