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Calling engineer types - exhaust technology

Discussion in 'General' started by HPPT, Apr 14, 2022.

  1. HPPT

    HPPT !!!

    Can someone think of a reason why a titanium exhaust header would produce one more horsepower than a similarly shaped header made of heavier metal?

    Supersport-spec R6, if that matters.
     
  2. 83BSA

    83BSA Well-Known Member

    Thinner wall thickness, hence larger ID?

    Cheers,

    Dave
     
  3. Mongo

    Mongo Administrator

    Similar isn't exact is my initial guess. ID of the Ti being slight smaller/larger is another. I wonder if the surface of Ti is smoother allowing for a hair better flow?

    Really though, 1hp is just too small for me to think it's more than a measurement fluctuation.
     
    tophyr likes this.
  4. 27

    27 Well-Known Member

    It has to do with the way different metals dissipate heat.

    Howerton, the Flat Track bike builder for Bryan Smith on Bo Lemastus’ Crosley Radio teams main business was building Indycar exhausts out of something better than Titanium... can’t remember what it is but he was able to pioneer the welding of it and it’s use in racing... guess it’s way better and way more expensive... maybe top secret as I don’t even remember what material it is ;)
     
    BigBird, Trainwreck and SpeedyE like this.
  5. HPPT

    HPPT !!!

    Okay, for this exercise, let's go with the assumption that the header was designed from the inside out. Same diameter inside, whatever that works out to on the outside.

    The guys making the decision have enough dyno experience that they decided it was worth going with titanium even though that prevented them from solving a problem that triggered the experiment in the first place.
     
  6. HPPT

    HPPT !!!

    Interesting. Would that matter on a single dyno pull, before things run too hot?
     
  7. Mongo

    Mongo Administrator

    Inconel?
     
    Knotcher, CBRRRRR999 and 27 like this.
  8. 27

    27 Well-Known Member

    Think of it like this Papa... a piece of Ti will cool way faster than stainless and that faster than say iron... so as the exhaust flows through it, the heat temp exchange creates like a vacuum to suck the spent gasses/exhaust out of the head/cylinder
     
    Wingnut likes this.
  9. Mongo

    Mongo Administrator

    I figured they knew what they were doing, granted experience like that on a racing team doesn't always preclude insanity - Ti is just cool after all and one pony is one pony! :D
     
  10. 27

    27 Well-Known Member

    It’s going to drive me nuts... can’t remember... Nan would know... it’s all the Indy guys use...
     
  11. HPPT

    HPPT !!!

    The idea was to make the bike heavier because of a rule change. I suggested the header. After the test, it wasn't retained.
     
    27 likes this.
  12. Riot

    Riot Well-Known Member

    Titanium generally has a lower thermal conductivity than stainless steel, so there is a small chance that this could yield a benefit, depending on the application (bike/tuning goal specific)

    Basically, the exhaust might stay hotter longer, resulting in a higher local speed of sound, resulting in better flow.

    Of course, you could achieve the same effect with a few feet on pipe wrap.

    Not to dismiss Mongos theory that it is mostly rounding error on an R6.
     
    HPPT and 27 like this.
  13. 27

    27 Well-Known Member

    For sure... dyno runs vary greatly depending on the heat of certain parts of the bike.... like old school... if the carbs were hot or cold, exhaust too... fuel of course... so many variables... the Buell gas tank frame cost them I think it was 7hp because the fuel was always hot from the heat transfer from the engine to the frame
     
  14. Mongo

    Mongo Administrator

    Can't lose that pony :D

    Would make sense, header is nicely spread out weight. But no matter what, Ti is still cool even if stainless would help the weight.
     
  15. ChemGuy

    ChemGuy Harden The F%@# Up!

    F1 uses...or used....Inconel 625. Very thin and strong...high heat resistance
     
    27 likes this.
  16. 27

    27 Well-Known Member

    Suggest a shake weight! :D

    If nothing else just for the laughs.
     
    turner38, TurboBlew and CBRRRRR999 like this.
  17. HPPT

    HPPT !!!

    It might improve the handling. They had a version of that in F1 until it was banned. :D
     
  18. 27

    27 Well-Known Member

    That’s funny... was the F1 driver holding/using it while driving? Switching hands between corners to be well balanced?

    :D J/K of course but I could see some of the pretentious pompass asses pulling them out of their purses and shaking it up!

    Told you I know nothing about F1 :crackup:

    Was it a damper of sort? An old racing buddy is making and selling something similar for dirt bikes called CounterShocks that mount by the triples.
     
  19. HPPT

    HPPT !!!

     
    27 likes this.
  20. CBRRRRR999

    CBRRRRR999 Well-Known Member

    Speed-talk has quite a few very long winded discussions on just about every aspect of engine building and tuning if you want the nerdly explanations.
    FWIW astonishing engine outputs have been had w mild steel, titanium, stainless and iconel. With and without internal or external coatings. For four strokes, exhaust isn't the magic bullet they are with proper motors.
     
    HPPT likes this.

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