Speed-Talk is running on www.Speed-Talk.com

IMPORTANT: Update your bookmarks to https://www.speed-talk.com/forum/
(Right-click the URL and select "Bookmark this link")

Any downsides to anti reversion mufflers/devices?

General engine tech -- Drag Racing to Circle Track

Moderator: Team

F-BIRD'88
Guru
Guru
Posts: 8130
Joined: Tue Mar 27, 2007 6:56 pm
Location: Ontario, Canada

Re: Any downsides to anti reversion mufflers/devices?

Post by F-BIRD'88 »

I am curious if these Anti-Reversion chambers will help a Mid-Length header to restore some of the low/mid range torque loss VS a long tube header.. Have a situation where a long tube header will be a pain and a off the shelf Mid length header fits and makes life much easier.
need a 2.50" in 2.50" out version. 460 -520 horsepower output.

Engine makes great torque with long tubes. Would like to keep (most of) that thrua Mid Length header.
-Hedman #68600-

(the long tube header baseline is not a optimized header
at all . Off the shelf street stuff)
F-BIRD'88
Guru
Guru
Posts: 8130
Joined: Tue Mar 27, 2007 6:56 pm
Location: Ontario, Canada

Re: Any downsides to anti reversion mufflers/devices?

Post by F-BIRD'88 »

If the Anti- Reversion chambers reduce exhaust reversion and thus reduce exhaust gas dilution in the combustion chamber the reduction in residual exhaust gas remix should speed up combustion speed. Spark timing adjustment may be nessessary to optimize with now resulting LESS EGR effect.
If your engine seemed to be hungry for more spark advance than others similar, the anti reversion chambers may correct this. A minor carb jetting tweek msy be called for also.
Exhaust gas doesn't burn.. Less exhaust gas dilution allows for more air/fuel to combust.
Carnut1
Guru
Guru
Posts: 4579
Joined: Tue Jun 11, 2013 6:32 pm
Location: Melbourne fl.

Re: Any downsides to anti reversion mufflers/devices?

Post by Carnut1 »

Bill Chase wrote: Fri Feb 19, 2021 5:28 am
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
I extended tge 3" collector and welded custom flanges to connect the full 3.5" exhaust with an H pipe. Early 90's
Servedio Cylinder Head Development
631-816-4911
9:00am - 9:00pm EST
pcnsd
Expert
Expert
Posts: 541
Joined: Thu Dec 13, 2012 12:04 am
Location: North County San Diego CA

Re: Any downsides to anti reversion mufflers/devices?

Post by pcnsd »

digger wrote: Wed Jul 03, 2019 6:22 am they could potentially alter the pressure waves at certain rpms which may have negative consequences
Digger,
Are you able to model these shapes in EngMod4T?
When I try to visualize what happens with an AR device regarding pressure wave vs particle flow. I can see that particle flow is effected by the shape. Pressure? That is less than clear to me. It may be delayed (spread over time), but I also think it possible the shape may have no effect on the progression of pressure waves within a tube system.
Can you educate me?
- Paul
RW TECH
Guru
Guru
Posts: 2267
Joined: Thu Nov 24, 2005 9:08 pm
Location: DETROIT, MI

Re: Any downsides to anti reversion mufflers/devices?

Post by RW TECH »

I tested a pair of anti-reversion devices in the collectors of a 424 CID SB2.2 dirt late model engine and they filled a 90 lb ft "hole" in the torque curve just under 3K RPM.

There were slight low single digit losses here & there in the curve (4000-8000 RPM sweeps @ 300 RPM/sec), but nothing that would offset the big TQ gain
NewbVetteGuy
Expert
Expert
Posts: 504
Joined: Sun Aug 07, 2016 4:11 pm
Location:

Re: Any downsides to anti reversion mufflers/devices?

Post by NewbVetteGuy »

For what it's worth CrateInsider.com's advice on the DynaTech/Hendren / Crate Insider AR "mufflers" is: "the longer the primary is, the closer you want the muffler to the collector; shorter primaries like 12-14" before AR muffler."

They say on a 604 circle track crate they're worth 15-25 ft lbs between 2,500 and 4,500 RPM. (275/280 roller cam @ lash, 208/221 @ 0.050", .474"/510" on 112 LSA).

--I wish I felt like I had a good guess for why a shorter primary would would want the AR muffler at a longer distance from the collector...


Adam
skinny z
Expert
Expert
Posts: 532
Joined: Tue Mar 11, 2008 8:42 am
Location: Alberta Canada

Re: Any downsides to anti reversion mufflers/devices?

Post by skinny z »

digger wrote: Wed Jul 03, 2019 6:22 am they could potentially alter the pressure waves at certain rpms which may have negative consequences
Or possibly improve the pressure wave tuning no?
Gathering parts and knowledge...
skinny z
Expert
Expert
Posts: 532
Joined: Tue Mar 11, 2008 8:42 am
Location: Alberta Canada

Re: Any downsides to anti reversion mufflers/devices?

Post by skinny z »

NewbVetteGuy wrote: Tue Feb 23, 2021 8:33 pm For what it's worth CrateInsider.com's advice on the DynaTech/Hendren / Crate Insider AR "mufflers" is: "the longer the primary is, the closer you want the muffler to the collector; shorter primaries like 12-14" before AR muffler."

They say on a 604 circle track crate they're worth 15-25 ft lbs between 2,500 and 4,500 RPM. (275/280 roller cam @ lash, 208/221 @ 0.050", .474"/510" on 112 LSA).

--I wish I felt like I had a good guess for why a shorter primary would would want the AR muffler at a longer distance from the collector...


Adam
This looks like a job for Larry Meaux and PipeMax.
Gathering parts and knowledge...
F-BIRD'88
Guru
Guru
Posts: 8130
Joined: Tue Mar 27, 2007 6:56 pm
Location: Ontario, Canada

Re: Any downsides to anti reversion mufflers/devices?

Post by F-BIRD'88 »

I wish I felt like I had a good guess for why a shorter primary would would want the AR muffler at a longer distance from the collector/i]

The AR chambers may causevan effect as if the short primarys act as being longer.
A faux secondary pipe.
digger
HotPass
HotPass
Posts: 2205
Joined: Sun Jan 27, 2008 6:39 am
Location:

Re: Any downsides to anti reversion mufflers/devices?

Post by digger »

skinny z wrote: Tue Feb 23, 2021 9:28 pm
digger wrote: Wed Jul 03, 2019 6:22 am they could potentially alter the pressure waves at certain rpms which may have negative consequences
Or possibly improve the pressure wave tuning no?
yes, IMO normally it helps somewhere but is worse somewhere else as well.
digger
HotPass
HotPass
Posts: 2205
Joined: Sun Jan 27, 2008 6:39 am
Location:

Re: Any downsides to anti reversion mufflers/devices?

Post by digger »

pcnsd wrote: Fri Feb 19, 2021 10:39 pm
digger wrote: Wed Jul 03, 2019 6:22 am they could potentially alter the pressure waves at certain rpms which may have negative consequences
Digger,
Are you able to model these shapes in EngMod4T?
When I try to visualize what happens with an AR device regarding pressure wave vs particle flow. I can see that particle flow is effected by the shape. Pressure? That is less than clear to me. It may be delayed (spread over time), but I also think it possible the shape may have no effect on the progression of pressure waves within a tube system.
Can you educate me?
i have not had a chance to look at this. in theory yes. as there is a "collector style" intended for anti reversion devices when i was looking at the user manual but id need to ask Vannik as there was something i was unsure of.
RevTheory
HotPass
HotPass
Posts: 5441
Joined: Thu Sep 04, 2014 6:45 am
Location:

Re: Any downsides to anti reversion mufflers/devices?

Post by RevTheory »

I'm curious as to whether or not there's enough volume in that little chamber that's mostly inner tube to actually cause pressure waves to reflect.
n2omike
Expert
Expert
Posts: 857
Joined: Sat Sep 02, 2006 10:56 pm
Location: West Virginia

Re: Any downsides to anti reversion mufflers/devices?

Post by n2omike »

These look like the 'bombs' they have been installing in Motocross exhaust systems for years now. I wondered if/when they would make the transition.
xxdabroxx
New Member
New Member
Posts: 33
Joined: Wed Jul 22, 2020 10:38 am
Location: Central CA

Re: Any downsides to anti reversion mufflers/devices?

Post by xxdabroxx »

Is that what is inside one of those? I always figured it was just an expansion chamber of sorts but it would make a lot of sense if they were mini versions of these.
User avatar
Rick!
HotPass
HotPass
Posts: 236
Joined: Fri Jan 01, 2016 4:13 pm
Location:
Contact:

Re: Any downsides to anti reversion mufflers/devices?

Post by Rick! »

n2omike wrote: Wed Feb 24, 2021 8:40 am These look like the 'bombs' they have been installing in Motocross exhaust systems for years now. I wondered if/when they would make the transition.
The "Powerbomb" pipe is basically a bulge with a perforated liner. Not so much anti-reversion. The Megabomb is a bit different with a larger chamber. It appears that Hytech has a patented anti-reversion chamber. Back last century, you could buy headers with AR cones in each pipe, at the header flange.
Post Reply