Any downsides to anti reversion mufflers/devices?

[dfarr67]

The existing bullet is after the cat about 20in, the bullet is there because I had it on hand- no other reason- I am running a proper muffler as well.

[F-BIRD'88]

How many mufflers total?
A cat + a bullet muffler + a "proper muffler" ?

Excessive restriction creates more ex reversion on cammed engines.

[dfarr67]

As it is, as a DD- it is barely tolerable noise wise. If I was to do it again- I would likely use a aerochamber. Existing muffler is Donaldson.

[lc-gtr-1969]

Sorry for dragging up an old thread, I just thought I would comment my experience with a Dynatech torque booster/ anti reversion chamber...

I installed one yesterday on my 350hp inline 6 running a 252/260@50 cam and a big port cylinder head designed for high rpm.

No dyno data but I can definitely say part throttle torque has increased from 2500 onwards. When feathering the throttle around a bend the car feels much more responsive and pulls easier onto the cam. A definite improvement.

I have not noticed much change with full throttle hp. On a street or circuit car I would not hesitate to install these. I can see pulling out of a corner would be improved for circuit work. You could hold the taller gear where without the booster I would probably drop back another gear.

I did not really notice any real difference to sound.

Just thought I would share!

[RevTheory]

How far back did you place it?

[RW TECH]

A pair of anti reversion "mufflers" placed directly after the header collectors filled in a 90 lb ft hole in torque curve of a 424 CID SB2.2 dirt late model engine @ 2500-ish RPM with no significant difference in power everywhere else in the curve.

Very helpful on slow restarts.

[dynoflo]

food for thought. thats a lot of overlap for a tiny cam.

[1972ho]

https://crateinsider.com/using-anti-rev ... ree-power/

[lc-gtr-1969]

How far back did you place it?

It's in the only spot that fits really, which was about 15 inches from the start of the collector.

food for thought. thats a lot of overlap for a tiny cam.

Can't say I would call my cam tiny, and not sure how you worked out the overlap without knowing where the centres are, unless you are referring to another cam?

[Chris_Hamilton]

@lc-gtr-1969
You got any video of that motor of yours. I would love to see it (and hear it) if you do. I love inline sixes.

[lc-gtr-1969]

@lc-gtr-1969
You got any video of that motor of yours. I would love to see it (and hear it) if you do. I love inline sixes.

https://www.youtube.com/watch?v=N-U61tWYaDU

[dynoflo]

sorry about tiny cam. Was looking at mopar numbers.

[skinny z]

A pair of anti reversion "mufflers" placed directly after the header collectors filled in a 90 lb ft hole in torque curve of a 424 CID SB2.2 dirt late model engine @ 2500-ish RPM with no significant difference in power everywhere else in the curve.

https://crateinsider.com/using-anti-rev ... ree-power/

This may have been touched already but this appears to me to be much the same principle as the exhaust termination boxes used to simulate an open header. Those however depend on volume to create the reflected pulse as well as a similar placement of the collector entering the chamber.
Is this to say the anti-reversion chambers from crateinsider.com are accomplishing the same thing with a much smaller package? If I'm not mistaken I believe the conventional termination box has to be equal in volume to the CID of the engine. Or half that if two are employed.

[lc-gtr-1969]

sorry about tiny cam. Was looking at mopar numbers.

I thought that may be the case, no problems, cheers bud!

[lc-gtr-1969]

A pair of anti reversion "mufflers" placed directly after the header collectors filled in a 90 lb ft hole in torque curve of a 424 CID SB2.2 dirt late model engine @ 2500-ish RPM with no significant difference in power everywhere else in the curve.

https://crateinsider.com/using-anti-rev ... ree-power/

This may have been touched already but this appears to me to be much the same principle as the exhaust termination boxes used to simulate an open header. Those however depend on volume to create the reflected pulse as well as a similar placement of the collector entering the chamber.
Is this to say the anti-reversion chambers from crateinsider.com are accomplishing the same thing with a much smaller package? If I'm not mistaken I believe the conventional termination box has to be equal in volume to the CID of the engine. Or half that if two are employed.

I do not think these AR Chambers are quite the same as termination boxes, both may help minimise reversion for obvious reasons, but as you suggest, I am not sure the AR chambers have the volume or dramatic change in area that a termination box will have to induce the engine thinking it has open headers.

If I could fit a termination box I would run one but room is quite tight under there...