Understanding Reversion
Stellar HDF Member
Joined: Jan 2013
Posts: 2,721
Likes: 103
From: St. Louis, MO
1997Bagger, thanks again for posting this.
I am flat amazed how $1.18 in thumb screws have made my bike significantly peppier on the highway. Thank you for taking your time to post this up.
https://www.hdforums.com/forum/softa...l#post14137528
Next I'll try power cones and see if they make a difference too.
I'll need to pull my plugs - wish I'd done it before I installed these, but I didn't so I'll have to see how they look after 50 miles with the mod and check it again later after a few hundred miles.
I am flat amazed how $1.18 in thumb screws have made my bike significantly peppier on the highway. Thank you for taking your time to post this up.
https://www.hdforums.com/forum/softa...l#post14137528
Next I'll try power cones and see if they make a difference too.
I'll need to pull my plugs - wish I'd done it before I installed these, but I didn't so I'll have to see how they look after 50 miles with the mod and check it again later after a few hundred miles.
Outstanding HDF Member
Joined: Apr 2012
Posts: 2,938
Likes: 30
From: North Florida
Reversion cones are basically reversion traps, you see them in mufflers to trap the sound wave as it returns up the pipe. In drag pipes they also work to increase the velocity of the exhaust at lower RPMs and increase the bottom end/mid range torque.
This is basically the same as running smaller valves, small intake and small exhausts, the velocity is what makes the torque.
The problem is while they work great at lower RPMs because they make a smaller exhaust exit they also restrict the flow at higher RPMs to the point that they kill top end HP, much the same as baffles.
This is basically the same as running smaller valves, small intake and small exhausts, the velocity is what makes the torque.
The problem is while they work great at lower RPMs because they make a smaller exhaust exit they also restrict the flow at higher RPMs to the point that they kill top end HP, much the same as baffles.
Stellar HDF Member
Joined: Jan 2013
Posts: 2,721
Likes: 103
From: St. Louis, MO
Reversion cones are basically reversion traps, you see them in mufflers to trap the sound wave as it returns up the pipe. In drag pipes they also work to increase the velocity of the exhaust at lower RPMs and increase the bottom end/mid range torque.
This is basically the same as running smaller valves, small intake and small exhausts, the velocity is what makes the torque.
The problem is while they work great at lower RPMs because they make a smaller exhaust exit they also restrict the flow at higher RPMs to the point that they kill top end HP, much the same as baffles.
This is basically the same as running smaller valves, small intake and small exhausts, the velocity is what makes the torque.
The problem is while they work great at lower RPMs because they make a smaller exhaust exit they also restrict the flow at higher RPMs to the point that they kill top end HP, much the same as baffles.
I was looking for a dyno sheet of power cones vs no power cones but have come up empty so far.
This dyno sheet I cribbed from the video above, showing the difference between mufflers, 90 degree thumb screw, 45 degree thumbscrew and open pipe, really opened my eyes. Note how the 90 degree thumbscrew gives you 75% of your lost torque back with virtually no decrease in upper end HP or TQ. And you keep the sound some of us like.
At $1.18, that's a pretty cheap lunch to me! I'm quite happy with this mod.
Stellar HDF Member
Joined: Jan 2015
Posts: 2,504
Likes: 150
From: ct
Reversion cones are basically reversion traps, you see them in mufflers to trap the sound wave as it returns up the pipe. In drag pipes they also work to increase the velocity of the exhaust at lower RPMs and increase the bottom end/mid range torque.
This is basically the same as running smaller valves, small intake and small exhausts, the velocity is what makes the torque.
The problem is while they work great at lower RPMs because they make a smaller exhaust exit they also restrict the flow at higher RPMs to the point that they kill top end HP, much the same as baffles.
This is basically the same as running smaller valves, small intake and small exhausts, the velocity is what makes the torque.
The problem is while they work great at lower RPMs because they make a smaller exhaust exit they also restrict the flow at higher RPMs to the point that they kill top end HP, much the same as baffles.
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