2 into 1 exhaust?

Discussion in 'Dakar champion (950/990)' started by BigMac, Jul 15, 2005.

  1. Nightstalker

    Nightstalker YO BUDDYPAL!

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    I'd sure love to get all that exhaust heat off my right foot!!!

    #41
  2. Flanny

    Flanny Flanny-it-up!

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    Hmmm...that's interesting, but not what I'm after...I want the header and collector down low, and then a high exit pipe like on the 950 Rallye, or possible a dual high exit pipe like on the 660 Rallye (I'd like to keep my ti Wings if possible)

    My "spare" header pipes came in today...within a few months (sigh...I'm too damned busy), I'll have someting done.
    #42
  3. K2m

    K2m ....58....

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    I'm a fense sitter on this


    BigMac's idea is value because of keeping the original headers and the power they produce.......... plus cheep.... 1 muffler 1 fuel tank KATO's collector makes this possible

    STEPHEN's idea of getting the luggage in is a very good idea. I hardly use my panniers because they are too wide. You loose the advantage in traffic of having a bike.

    I like FLANNY's idea of running two mufflers(the ones I have now) 660 stile with 2 10lt fuel tanks. I think that we will lose our centre stands Flanny!

    Keep the ideas cumming boys!!!!!
    #43
  4. pRICK

    pRICK Been here awhile

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    75 degree 4 stroke vee twin. Yer pipes wont work by simply making a two into one at the header. Most pipe manufacturers I have talked to cant find enough room to get correct pipe lengths to make a high two into one system work. The only way to make a cost effective two into one system work on a 950 is a low pipe like the Rallye IMO.
    #44
  5. Flanny

    Flanny Flanny-it-up!

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    Yeah...the centre stand is toast...but I would gladly give it up for another 100kms of range.
    #45
  6. K2m

    K2m ....58....

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    75 degree 4 stroke vee twin. Yer pipes wont work by simply making a two into one at the header. Most pipe manufacturers I have talked to cant find enough room to get correct pipe lengths to make a high two into one system work. The only way to make a cost effective two into one system work on a 950 is a low pipe like the Rallye IMO.

    Quote from KTM@01

    KTM found enough room with the 990 Duke to make a 2 into 1. Do you agree?

    [​IMG][/img]

    Do you mean that a unequal length header two into one fall short in the power game?

    Or do you mean just from a cost effective point of view?

    Sorry mate, I am just not sure what you are trying to say..... Having looked at your previous posts I have the highest regard for your opinion. And if no one has said this then a BIG WELCOME to the list. We need people with your background and experience to this forum. :thumb
    #46
  7. Stephen

    Stephen Long timer Supporter

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    Looks to me that the SupaDuka header will foul the Adventure starboard tank. The pipes also go very low, well under the bike, which is great for a Duke but not for a dualsport.

    Bring me the rally headers! Really, that would be the simple solution. Coated with that fancy ceramic shit, maybe even some o'that racer exhaust tape, keep my foot and fuel cool, fool. :D Slap a silencer on low, and go. :thumb
    #47
  8. pRICK

    pRICK Been here awhile

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    Yes KTM engineers have probably designed this system with correct pipe lengths to make it work. There is room with a low system to get correct lengths. If you cut away the storage area under the seat on a 950 Adventure you may be able to bend a pipe to the correct lengths and make it work. Might sound simple but it is not, there are many variables.
    I will try to explain as simply as possible. We will only talk about twin cylinder bikes. One complete cycle of both cylinders would be a total of 720 degrees of crankshaft rotation. The purpose of a tuned length exhaust system is to get each exhaust pulse to create a low pressure at the collector from cyl # 1 to draw the exhaust from cyl # 2 and then cyl # 2 creates a low pressure to draw the exhaust from cyl # 1 etc. etc. etc. A horizontally opposed twin with 180 degree crank throws could in theory use equal length pipes with each cylinder firing at 360 degrees apart. A 90 degree twin would have exhaust pulses at say 360 degrees of crank rotation and then at 630 degrees of crank rotation. Equal length pipes to the collector wont work because of the unequal duration between exhaust pulses. Different length pipes are required to time the pulses evenly. Similar principle applies on the 950 with 75 degree vee. With incorrect pipe lengths it is possible to have # 1 cylinder exhaust pulse create a low pressure and # 2 cyl exhaust pulse create a high pressure restricting exhaust flow from # 1 causing poor scavenging of # 1 cylinder. Resulting damage can include burnt out valves or excessive carbon on valves of one cylinder etc. etc.. The variables????? Front cylinder pipe will run cooler in clear air flow therefore exhaust gasses, heat, pressure (velocity) will be less from front to rear for equal length of pipe blah blah blah blah. Like I said, many variables. With the pictured home made two into one system exhaust temperatures will be different between the two cylinders, tuning may be necessary to rectify any heat problem (lean running condition) with a reduction in horsepower the probable result. I have read this again and I think it makes sense but it is very basic.

    Point I am trying to make is best case scenario will be loss of horsepower/torque, worst case will be engine damage. If you make major exhaust changes get your bike on a dyno to compare HP/torque curves to standard and monitor air/fuel ratio's and temperatures in a controlled environment. The noise it makes and seat of pants feel is nothing more than noise and goody goody feelings through you pants. And I haven't even mentioned balance pipes!!!!.
    #48
  9. K2m

    K2m ....58....

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    Please tell us about the part that balance pipes play in the equation.
    #49
  10. Flanny

    Flanny Flanny-it-up!

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    Yeah - I'll chime in here too since you really seem to know your stuff.

    Mine will be a two-into-two like on the 660 rallye, and effectively the same as the stock set-up, except with a low exit. So essentially just re-routing the existing configuration.

    I will essentially try to reproduce the stock individual header lengths (or at least length ratio). But, what I'd like to know about is the "cross over" which is currently just after the connection to the rear part of the pipe. I know that cross over allows scavenging and creates balance, but I will not be able to reproduce that short cross-over and also not it's exact position on the pipe.

    The best I could do in a low exit situation is a longer (8") cross over essentially just front of the rear wheel.

    So, would it be practical just not to have a cross over at all? (ie: have both cylinders be completely independant). Or is a croiss over critical to performance? If so, would a longish cross over serve the purpose?

    BTW - I don't mind sacrificing some peak power or torque, but what I don't want are big dips in the curves.

    Also, FWIW I plan on having proper Dyno testing done afterwards to get the jetting straight.

    Thanks for your insights.
    #50
  11. pRICK

    pRICK Been here awhile

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    Crossover or balance pipes can and do improve performance. They balance exhaust pulses or pressure between the two pipes and reduce noise. One would normally be fitted as close as possible to the headers and of the same diameter as the main system but probably not less than 75% of the diameter of the main system. With an 8" crossover I would definately make it the same size as the main system. Flanny it will be interesting to see your dyno results. To duplicate manufacturer pipe length ratios I fill each pipe with water and measure the quantities. Sounds simple and it works for me. (most times) Dynos and lap times tell the real story. I'm no expert, just learnt from mistakes
    #51
  12. Stephen

    Stephen Long timer Supporter

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    Now that's damn clever! :thumb

    That's just the kind of method I'd think of if I were as smart as I'd like to think I am. :huh
    #52
  13. K2m

    K2m ....58....

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    Flanny

    When the exhaust gas expands into the atmosphere it sands a pulse wave back through the pipe to stop the inlet charge from escaping the cylinder. This improves volumetric efficiency at a certain rev range. With the standard system this pulse probably comes from the exit of the cat into a large chamber surrounding the cat. Adding Acra's should improve performance considerably due to less exhaust presser for the pistons to push, but also alters the tuned length of the pipes. This could explain why there are no reports of big HP increases when adding these mufflers.

    So I would suggest that you measure from the end of the cat to the head. Then include the straight through muffler in your pipe length.

    I think KTM were serious with there pipe tuning as I notice that there pipe narrows a few inches after leaving the head. ie. if it widened it would need to be shorter for tuned length. That water trick is brilliant. :nod
    #53
  14. Flanny

    Flanny Flanny-it-up!

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    I have to sell the sub-frame and stock exhaust headers that I bought a few months ago...I don't have the time for this project, and need to clean out the shop...

    Here are the items after they closed on e-bay.

    http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=7985046065#ebayphotohosting

    http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=7985502460

    I'm looking for $450 us for the two items plus shipping...The sub frame alone (wihtout light and plastic is $450 retail, and each header is $200 Retail, so $450 is a steal...)...

    I'll also cross post this is the flea market...

    Cheers!
    #54
  15. Linjasika

    Linjasika Adventurer

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    Here is my SE with Devil Trophy.The mod is not ready yet and not tested but you can see what it looks like.[​IMG]

    Attached Files:

    #55
  16. Linjasika

    Linjasika Adventurer

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    And a closer look

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  17. Nightstalker

    Nightstalker YO BUDDYPAL!

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    Looks pretty damn sweet to me!!
    #57
  18. gefr

    gefr Life is a trip

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  19. RAGrote

    RAGrote Fishin w PICO

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    You will, of course, need testers.:deal :freaky
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  20. b0mb3r

    b0mb3r Old Git

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    bump :D
    #60