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| Daycruiser | | Chaac |  | | Reg. Date | : | 08/11/2011 | | Posts | : | 704 | | Location | : | Garner, NC, United States |
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| | Posted : 09 Feb 2014 - 16:27 Post title : Front Header Cross Over Pipe - Purpose? | | | We've talked the Cat Eliminator / X-Over topic to death but I've seen very little mention of the Front X-Over pipe at the Headers on the T-Birds. To those exhaust experts on here what is the function of that cross-over pipe? I can't tell if it's more for structural integrity of the headers or actually serves a purpose behind the sensor bungs? I'm having my headers modified to remove the stock bung and put in new bugs for the wide band sensors, so while the headers are at the machine shop thought about deleting this cross-over pipe unless it's really needed.
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| n3zat | | Set | |  | | Reg. Date | : | 18/09/2013 | | Posts | : | 171 | | Location | : | Coatesville, pa, United States |
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| | Posted : 09 Feb 2014 - 18:14 Post title : Re: Front Header Cross Over Pipe - Purpose? (Re: Daycruiser) | | | I can't really say on the bike although it may work the same , but on an auto using an x pipe or crossover will make an 8 cyl sound like an 8 cyl instead of sounding like two four cyl it blends the tone your bike being a two cyl will have a better tone instead of two one cylinders . its the only way on an auto that I've experienced this .
| Charlie
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| Daycruiser | | Chaac | | | Reg. Date | : | 08/11/2011 | | Posts | : | 704 | | Location | : | Garner, NC, United States |
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| | Posted : 09 Feb 2014 - 19:40 Post title : Re: Front Header Cross Over Pipe - Purpose? (Re: Daycruiser) | | | I think I've answered my own question. Read on some racing forums that the header cross-over plays a key role in exhaust scavenging lending that to low/mid range performance. It does also smooth out the exhaust pulses which goes to the point of exhaust sound. The cross over stays.
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| drhach | | Set | | | Reg. Date | : | 18/10/2011 | | Posts | : | 250 | | Location | : | Waukegan, Illinois, United States |
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| | Posted : 11 Feb 2014 - 14:02 Post title : Re: Front Header Cross Over Pipe - Purpose? (Re: Daycruiser) | | | It does provide scavenging and where you place it in the stream dictates the point in the RPM range where it has the most effect. You can also do multiple crossovers, but you get in to aesthetics issues if you have too many.
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| davetac1 | | Thunderbird | | | Reg. Date | : | 06/09/2010 | | Posts | : | 8,379 | | Location | : | Haverhill, Ma., United States |
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| | Posted : 12 Feb 2014 - 22:56 Post title : Re: Front Header Cross Over Pipe - Purpose? (Re: drhach) | | | The purpose of the cross over pipe is to keep the back pressure balanced or equal comin from both cylinders,or both banks if it's got more then one cylinder per bank so it breathes better.I believe the term is called reversion. I'm not sure about a triple cylinder.I owned one,but all three exhausts were independent of one another.But that was over 40 years ago and things have changed.So the newer triples probably do connect in some way for balance purposes. Anyone own a Speed Triple??? take a look at the exhaust and report back.PLEASE!! Dave!!!
| | Post edited by davetac1 on 12 Feb 2014 - 23:11 |
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| KingOfFleece | | Set | | | Reg. Date | : | 30/09/2009 | | Posts | : | 304 | | Location | : | United States |
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| | Posted : 13 Feb 2014 - 01:13 Post title : Re: Front Header Cross Over Pipe - Purpose? (Re: davetac1) | | | My Street 3 is 3 into 1 into 2. No crossover.
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| Daycruiser | | Chaac | | | Reg. Date | : | 08/11/2011 | | Posts | : | 704 | | Location | : | Garner, NC, United States |
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| | Posted : 13 Feb 2014 - 02:03 Post title : Re: Front Header Cross Over Pipe - Purpose? (Re: KingOfFleece) | | | Yep all sounds about right to me. Exhaust guy agreed that it had to stay. New Bungs installed now so time to install the AT-300 and be done with all the engine mods and put the bike back together for March riding season. There's 6 inches of snow on my driveway and it's pissing me off, if I wanted fucking snow I'd live in Essex County and listen to Dave whine about it. Damn it Dave, keep your crappy snow to yourself!! 
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| drhach | | Set | | | Reg. Date | : | 18/10/2011 | | Posts | : | 250 | | Location | : | Waukegan, Illinois, United States |
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| | Posted : 17 Feb 2014 - 19:47 Post title : Re: Front Header Cross Over Pipe - Purpose? (Re: Daycruiser) | | | I used to be involved with an engineer at Ford who designed exhaust systems for a living. He used to laugh at the term "back pressure". Back pressure, is not desirable and there is no design consideration for it (At least not at Ford, which carries some weight for me). Actually what he told me was that it really has no meanign for exhaust design. Crossovers allow you to tune the pulse that is coming from a cylinder and maintain the momentum of that mass so that you can get exhaust scavenging.
Think of the pulse of exhaust that is coming out of your pipe as a plug, there is a pressure wave in front of it and it's departure creates vacuum. If you time it right, that vacuum on the back end of the pulse can clean out your cylinder and allow a cleaner charge of new air/fuel to enter in it's place. It's not "back pressure", it's the node of a sine wave. The placement along the exhaust sytem coincides to the rpm that you are tuning for and the length of the exhaust wave.
I'm always tempeted ask, what are the units of "back pressure"? How do you measure it? Keep your crossovers. Triumph paid a lot fo really smart engineers to decide that's where it belongs.
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| surfing72 | | Set | |  | | Reg. Date | : | 20/03/2012 | | Posts | : | 483 | | Location | : | Nth, New South Wales, Australia |
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| | Posted : 17 Feb 2014 - 21:17 Post title : Re: Front Header Cross Over Pipe - Purpose? (Re: Daycruiser) | | | I actually welded a small plate the size of a coin to close the X over off in an attempt to give a more direct flow hoping to increase the volume of the exhaust. (I know nothing about exhaust - experiment only) and the bike idled like a HD - Sounded terrible - irregular idle. I removed the welded plate and returned the X over. It seems the X over is definatley a positive thing and mine is here to stay
| Dan
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| n3zat | | Set | | | | Reg. Date | : | 18/09/2013 | | Posts | : | 171 | | Location | : | Coatesville, pa, United States |
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| | Posted : 17 Feb 2014 - 21:54 Post title : Re: Front Header Cross Over Pipe - Purpose? (Re: surfing72) | | | I'm glad you said it there is a whole lot of BS out there and back pressure is one of them .
| Charlie
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| Linkdog | | Thor | |  | | Reg. Date | : | 10/02/2011 | | Posts | : | 2,952 | | Location | : | Groveland, FL., United States |
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| | Posted : 17 Feb 2014 - 22:41 Post title : Re: Front Header Cross Over Pipe - Purpose? (Re: Daycruiser) | | |
Daycruiser wrote:
Yep all sounds about right to me. Exhaust guy agreed that it had to stay. New Bungs installed now so time to install the AT-300 and be done with all the engine mods and put the bike back together for March riding season. There's 6 inches of snow on my driveway and it's pissing me off, if I wanted fucking snow I'd live in Essex County and listen to Dave whine about it. Damn it Dave, keep your crappy snow to yourself!! |
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At least now, Dave can get more TIME out of his tires
| Never drink from a cow with one udder! 2010 1600 Blue&White ( of course ) Long TORS and HP filter.
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