Short shots suck?
Short shots suck?
Everyone tells me that V&H short shots suck for performance and i should get a longer set of pipes to prevent reversion. So i look at some drag pipes from cycle shack and look at exhaust systems with mufflers and even the stock HD system. if you look at the pipe for the front cylinder on short shots and the front cyl pipe for cycle shack drags or stock HD theyre the same shape and stop at the same point right where the swingarm connects to the frame. So why does everyone say short shots are so bad for performance when the reality is theyre not that short? what am i missing?
HDF Community Team
Joined: Jun 2006
Posts: 12,778
Likes: 2,608
From: san antonio
Everyone tells me that V&H short shots suck for performance and i should get a longer set of pipes to prevent reversion. So i look at some drag pipes from cycle shack and look at exhaust systems with mufflers and even the stock HD system. if you look at the pipe for the front cylinder on short shots and the front cyl pipe for cycle shack drags or stock HD theyre the same shape and stop at the same point right where the swingarm connects to the frame. So why does everyone say short shots are so bad for performance when the reality is theyre not that short? what am i missing?
Ultimate HDF Member
Joined: Aug 2012
Posts: 6,470
Likes: 4
From: on the road
If reversion on short shots were that big of issue they wouldn't make them for fuel injected bikes.As far as the comment about short pipes and power that really isn't totally true as the rpm range they make power is just higher than a mufflered pipe.2 into 1 pipes seem to be producing the most power at this time dyno wise.
What doesnt make sense to me is that the short shots are the same overall length as stock pipes pretty much. So yes i know mufflers are on the stock pipes but why is it that mufflers are better then just having baffles? I know drag pipes suck for street performance but nobody can really explain the technical or mechanical reason as to why its so much better to have a 2 into 1 or a big dorky ugly looking muffler hanging on the side of your bike.
HDF Community Team
Joined: Jun 2006
Posts: 12,778
Likes: 2,608
From: san antonio
What doesnt make sense to me is that the short shots are the same overall length as stock pipes pretty much. So yes i know mufflers are on the stock pipes but why is it that mufflers are better then just having baffles? I know drag pipes suck for street performance but nobody can really explain the technical or mechanical reason as to why its so much better to have a 2 into 1 or a big dorky ugly looking muffler hanging on the side of your bike.
Ultimate HDF Member
Joined: Aug 2012
Posts: 6,470
Likes: 4
From: on the road
I think you misinterpreted my statement-----------------that was the fuel injected motors have a bigger tendency towards reversion than a carbed motor just due to design----------------------basically cams,heads,compression ratio etc doesn't have much to do with reversion on the grand scale.A set of 2 inch or bigger drag pipes will have reversion on a stock engine but might not on a big hairy cammed monster.Length of pipe doesn't matter but RESTRICTION does it needs to be just enough to stop the slinky affect the sound waves have in the pipe
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HDF Community Team
Joined: Jun 2006
Posts: 12,778
Likes: 2,608
From: san antonio
I think you misinterpreted my statement-----------------that was the fuel injected motors have a bigger tendency towards reversion than a carbed motor just due to design----------------------basically cams,heads,compression ratio etc doesn't have much to do with reversion on the grand scale.A set of 2 inch or bigger drag pipes will have reversion on a stock engine but might not on a big hairy cammed monster.Length of pipe doesn't matter but RESTRICTION does it needs to be just enough to stop the slinky affect the sound waves have in the pipe
Every four stroke internal combustion engine has reversion; some more than others. Reversion is nothing more than the event that occurs when both the intake and exhaust valves are open near to completion of the exhaust cycle when cylinder pressure is greater than atmospheric and combustion residue is forced into the intake flow until cylinder pressure and atmoshpheric pressure equalize and the reversion flow stops.
If you look at the below illustration, it should be obvious that valve timing and compression very much affect reversion.
Not trying to start a pissing contest, just trying to clarify.
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Road Master
Joined: Jul 2011
Posts: 1,016
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From: West New york, NJ
Reversion on a straight, no baffle, no muffler pipe always takes place. The idea is to measure the length of the wave length and have your pipes match that. The wave length is different depending on where the motor makes its power.Once you baffle etc. You break that wave.
