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Any downsides to anti reversion mufflers/devices?

General engine tech -- Drag Racing to Circle Track

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Mikej26
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Any downsides to anti reversion mufflers/devices?

Post by Mikej26 »

I recently installed a set of dynatech anti reversion mufflers after my header collectors and picked up a good deal of low and mid range torque and throttle response. 360 sbc 11:1 comp, lightly ported profiler 195cc heads, hydro roller 242/248 @.050 Headers are 1 3/4” primaries with a merge collector going into a full length 3 inch exhaust with an x pipe.

Basically the addition of these restored the off idle and cruise rpm part of the power and with zero negative impact on the top end power, might actually be better up top too.

Just wondering if there’s ever any reason not to run them since they seem to help so much with no perceived negative trade off
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Re: Any downsides to anti reversion mufflers/devices?

Post by digger »

they could potentially alter the pressure waves at certain rpms which may have negative consequences
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Re: Any downsides to anti reversion mufflers/devices?

Post by RevTheory »

Love it when that happens. Did you install them at any specific length?
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Re: Any downsides to anti reversion mufflers/devices?

Post by BradH »

How much effective collector length is there before the anti-reversion comes into play? I'm asking in terms of the actual collector length of the header plus any straight pipe extension prior to the anti-reversion cut-off, whether internal or external to the AR device.

Also, had the combination been tested with that same effective collector length prior to adding the AR piece?
Last edited by BradH on Wed Jul 03, 2019 12:15 pm, edited 2 times in total.
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Re: Any downsides to anti reversion mufflers/devices?

Post by Carnut1 »

MIke, I have had similar results with a.r. . I couldn't find any down side. Thanks, Charlie
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Mikej26
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Re: Any downsides to anti reversion mufflers/devices?

Post by Mikej26 »

RevTheory wrote: Wed Jul 03, 2019 9:41 am Love it when that happens. Did you install them at any specific length?
I really just got them in there where I could fit them. Ended up being that I could cut the collector extensions down to 4” and slip fit the A.R./torque boosters onto those. They just fit in there ahead of the 60 degree bends leading to the x pipe.

I was apprehensive about whether to install them or not because I wasn’t sure how they’d interact with the merge collectors. The merge collectors pinch down to 2 1/2” after the primaries and open up to 3”. The dynatech A.R./torque boosters ar 3” intlet and outlet, but when closely looking at how they’re constructed the intlet piece that extends into the AR chamber actually has a taper to it the goes back down to 2 1/2”.

So I was and still am having a hard time wrapping my head around how having two choke points in relatively close proximity to each other would work together. My concern was that they’d net a negative effect, my hope was that they’d have a synergistic effect.
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Re: Any downsides to anti reversion mufflers/devices?

Post by Mikej26 »

BradH wrote: Wed Jul 03, 2019 11:40 am How much effective collector length is there before the anti-reversion comes into play? I'm asking in terms of the actual collector length of the header plus any straight pipe extension prior to the anti-reversion cut-off, whether internal or external to the AR device.

Also, had the combination been tested with that same effective collector length prior to adding the AR piece?
I really just got them in there where I could fit them. Ended up being that I could cut the collector extensions down to 4” and slip fit the A.R./torque boosters onto those. They just fit in there ahead of the 60 degree bends leading to the x pipe.

I ran the same exhaust prior with straight 3” pipe taking up the space of the A.R.

A 6” length on straight pipe is what was removed to accommodate the installation of the A.R devices.

But my exhaust is 3” from the 3” collector all the way to the x pipe, so it’s essentially all collector prior to these being placed if I’m not mistaken.
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Re: Any downsides to anti reversion mufflers/devices?

Post by Mikej26 »

Here's a pic of the current set up.
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Re: Any downsides to anti reversion mufflers/devices?

Post by milenkogt »

Thanks for sharing your input on these Mike.

I have a 2019 charger 392 that I installed the stainless dynatech AR chambers into the midpipes.

The cam profile has 46* of overlap and you can start to really feel the power come on around 3k rpm.

The 392 is 11:1 comp, and cam specs from what I've found are

Lift .574" / .541"
Duration @ .050 215/221

Intake Opens (BTDC) 36.0°
Closes (ATDC) 250.0°
Duration 286.0°

Exhaust Opens (BTDC) 278°
Closes (ATDC) 10°
Duration 288.0°

VVT cam phasing range 37*


Hopefully these anti reversion chambers will gain in the lower and mid range.

I'm curious if they will change the sound too?

Mike, did you have any before and after dyno results by chance?

Also, did you notice any change in sound overall?

Thanks for any feedback, it's been tough to find dyno results, but most people seem to state positive results!

Here are the midpipes with the anti reversion chambers.

Image
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Re: Any downsides to anti reversion mufflers/devices?

Post by Warp Speed »

Mikej26 wrote: Wed Jul 03, 2019 12:38 am I recently installed a set of dynatech anti reversion mufflers after my header collectors and picked up a good deal of low and mid range torque and throttle response. 360 sbc 11:1 comp, lightly ported profiler 195cc heads, hydro roller 242/248 @.050 Headers are 1 3/4” primaries with a merge collector going into a full length 3 inch exhaust with an x pipe.

Basically the addition of these restored the off idle and cruise rpm part of the power and with zero negative impact on the top end power, might actually be better up top too.

Just wondering if there’s ever any reason not to run them since they seem to help so much with no perceived negative trade off
How was the performance impact tested?
Seat of the pants, chassis dyno, track times ect. ?
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Re: Any downsides to anti reversion mufflers/devices?

Post by Mikej26 »

Warp Speed wrote: Sat Nov 16, 2019 8:14 am
Mikej26 wrote: Wed Jul 03, 2019 12:38 am I recently installed a set of dynatech anti reversion mufflers after my header collectors and picked up a good deal of low and mid range torque and throttle response. 360 sbc 11:1 comp, lightly ported profiler 195cc heads, hydro roller 242/248 @.050 Headers are 1 3/4” primaries with a merge collector going into a full length 3 inch exhaust with an x pipe.

Basically the addition of these restored the off idle and cruise rpm part of the power and with zero negative impact on the top end power, might actually be better up top too.

Just wondering if there’s ever any reason not to run them since they seem to help so much with no perceived negative trade off
How was the performance impact tested?
Seat of the pants, chassis dyno, track times ect. ?
Just butt dyno and increased traction issues
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Re: Any downsides to anti reversion mufflers/devices?

Post by Protech Racing »

Is there actual BTB dyno testing ?
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Re: Any downsides to anti reversion mufflers/devices?

Post by Mikej26 »

No, I wish I had that. But I do not.
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Re: Any downsides to anti reversion mufflers/devices?

Post by Bill Chase »

Carnut1 wrote: Wed Jul 03, 2019 12:00 pm MIke, I have had similar results with a.r. . I couldn't find any down side. Thanks, Charlie
Have you used them with a straight collector vs a merge collector? And where in the system did you place them? Full street exhaust, or just headers with extensions
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Re: Any downsides to anti reversion mufflers/devices?

Post by Steve K »

I'm curious as to whether there is any noise reduction or change in sound. Also what part number did you use.
79 Cmaro, 427 sbc, Tunnel Ram Dual Quad with Eddy carbs, AFR 210 Race Ready heads, 263-272 @.50 Comp solid roller cam, 4.10's and a faceplated Tremec TKO 600.
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