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Discussion Starter #1
So I sent out an email to the major exhaust manufacturers 3 days ago about pipes/exhausts for our Cross-bikes. The only company to reply was CobraUSA. Their customer service department told me that they just received a 2011 cross country in on september 1 and that they are working on pipes for it. Earliest release date would be end of october. Great! Now that I had my mind made up on what I want, now I'm gonna wait to see what Cobra has to bring to the table.
Hopefully this is a start for other big name manufacturers to jump on the Cross-bike band wagon!
 

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Sweet!

Great news. Have they mentioned if they're up to a full exhaust system or just slip-ons? I cannot imagine letting go my D&Ds, but I can never say "never."
 

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full

Would love to see a full exhaust.....I emailed supertrapp they stated thhey do not plan on making an exhaust at this time
 

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Cobra is married to Vic, and it will be a dealer only system
Doesn't Cobra make most or all of Vic's exhaust systems?

Cobra recently came out with a special fuel tuner for HD's that caught my eye because it's an on the fly auto tune unit. So I emailed and asked if they will be making one for Victory and they said they did and it will be sold through the Victory dealerships. Maybe Victory chose not to market this device. Have you heard anything about it Kevin?

I think the HD unit was selling for around $500.
 

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Discussion Starter #6
In the email, the guy only mentioned "pipes". Is it a full system, slip ons, or just their version of the baffles i dont know. Witch such a short time from R&D to an actual product for sale (he sia dabout 2 months), i'm assuming it just a re-baffling. I'm sure new pipes needs more R&D time because of the backpressure needed.
 

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I'm sure new pipes needs more R&D time because of the backpressure needed.
It's about velocity, scavenging, reversion, and pulse length. Back pressure is a NEGATIVE side effect of a controlled exhaust flow. If back pressure actually made power. Corvettes would have corks in the pipes. Man I hate that misconception.
 

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It's about velocity, scavenging, reversion, and pulse length. Back pressure is a NEGATIVE side effect of a controlled exhaust flow. If back pressure actually made power. Corvettes would have corks in the pipes. Man I hate that misconception.
I'm not doubting what you're saying Kevin but the industry has been saying back pressure is a key element in exhaust systems forever. Perhaps it's an overly simplified was of saying it's a way of controlling the positive effects of those things you mentioned.

Are you saying there been a fundamental change in that belief?

Any word on the Cobra tuner?
 

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I'm not doubting what you're saying Kevin but the industry has been saying back pressure is a key element in exhaust systems forever. Perhaps it's an overly simplified was of saying it's a way of controlling the positive effects of those things you mentioned.

Are you saying there been a fundamental change in that belief?

Any word on the Cobra tuner?
It has never been about back pressure, and those in the industry that say it; do not know what they are talking about. I can remember my father being iritated when I was a little kid....by the same topic. The artical linked in an earlier post is excellent, and they do not prepetuate the myth about back pressure being a good thing
 

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Kevinx is absolutely correct. It always drives me nuts as well when I hear someone talk about needing backpressure in their pipes as well. I could go into a bunch of complicated engineering crap (laminar vs turbulent pipe flow, pulse and reversion waves, etc) but what Kevin said puts it best. All exhaust systems (and air intake systems for that matter) are optimized to work at one ideal exhaust gas velocity (engine rpm) and is a compromise at all other rpm ranges.

In very basic terms, smaller diameter and longer pipes do a better job a scavaging exhaust gases at low rpm ranges and larger diameter, shorter pipes perform better at high rpm ranges. If you design for high rpm performance your going to lose low rpm performance & vise versa. Its the reason why you see the high revving sport bikes putting EXUP valves in their pipes and cars like Ferraris switching between two different intake runners on their engines. They are trying to get the best of both worlds by having their high rpm performance while still trying to maintain good low rpm performance. Luckly, our low revving V-twins don't have a very large rpm operating range so it makes it much easier to design a good performing exhaust system. When people incorrectly state that they need more back pressure in their pipes what they are actually saying is they need an exhaust system that is optimized to flow better at lower rpm ranges which can be achieved by smaller diameter pipes, longer pipes, or you can use tuned muffler baffles to achieve similar results.


But personally I will never put another Cobra pipe on any bike I ever own. Years ago I had a Valkyrie that we put some Cobra 6 into 6 pipes that dropped 10HP on that bike. I spent countless hours adjusting carbs and dyno tuning that bike trying to get it to run like it used to. Finally we called Cobra directly about the pipes and their answer was "yeah, we know about the HP loss on those pipes. You can either have the HP or the sound but not both." The funny thing was that Vance & Hines made 6 into 6 pipes just like the cobras but they didn't lose any power with those. I for one will only buy pipes from a company that cares as much about peformance as they do about sound.
 

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So I was right when I said that using the term backpressure was an over simplification of the principles using velocity, scavenging, reversion, and pulse length.

In purely technical terms the word "backpressure" in this context doesn't apply but when using the vernacular to describe the engineering terms associated with having the right length/diameter/baffles; it applies perfectly.

I kinda doubt anyone is going to change how the wording on how this function of science/math is applied to exhaust systems in the industry for the average Joe on the street anytime soon.

JMHO, FWIW, YMMV
 

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The word backpressure only applies in as much as it is a negative side effect of poor decision making. VELOCITY is the word that makes the bike go vroooooom
Okay, okay, okay! You win!! :D

I was merely trying to point out, however wrong the term may be technically, it's the generic term for all the good stuff that makes it go vroooooom. ;)
 
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