Canister style expansion chamber

Discussion in 'Performance Mods' started by Fabian, Jun 13, 2013.

  1. Fabian

    Fabian Well-Known Member

    Can't wait for the day.

    Can you design a more compact low rpm torque pipe, like the older Curtis Youngblood (R/C) Muscle Pipe 5
    It's a compressed long pipe layered into a multi-tubular arrangement, thereby greatly reducing it's external length yet retaining the total length of a tuned pipe:


  2. geebt48cc

    geebt48cc Member

    HS, looks the part!~ I read what your saying, I was just unaware that you could put a 90 degree bend in exhaust in order to get full results? Once again, it does look the part!!!!!!! ;)
  3. Fabian

    Fabian Well-Known Member

    Because in Australia we drive on the other side of the road, so it is advantageous to keep the pipe on the left hand side, so when traffic (i.e police vehicles) drive past, it makes it more discrete by hiding the bulk of the pipe on the left hand side of the bike; obscuring most of it from the eyes of a police officer.
  4. HeadSmess

    HeadSmess Well-Known Member

    gas flow is not pressure waves! so yep, a pipe can look like a snail. or turn a ridiculously tight bend whilst still being effective.

    too tight a bend and the gas breaks into turbulence. doesnt effect the pipes workings but does effect general flow in the system...

    ahhh, curtis. old school heli master. the pipe itself though... hard to say.

    physics be physics, and you cant alter how far the waves need to travel.

    you cant "squash" a pipe into a shorter length concentrically.(unlike mirrors and lenses!)

    but you could, i guess, somehow snake it around, the pipe has to stay within dimensional limits...

    bends and joins equal time and money. tough luck. this clears everything nicely and should fit most frames and mounts entirely to the motor :)

    the curtis pipe just looks like a standard expansion chamber, fed in at right angles. an expansion chamber, not a tuned pipe. big difference. an expansion chamber is exactly that, a chamber for expansion. its more of a silencer than anything.

    helis require a fair bit of power but dont appreciate "pipey" behaviour, ie, powerbands etc. they want the motor to sit at various rpm's and stay there, predictably. they use 25% nitro for the power.

    even an R/C car can become unuseable when the pipes too effective!
  5. HeadSmess

    HeadSmess Well-Known Member

    oink oinks? boys in blue? so far ive been lucky but then again, is a point....


    joins equal time and money that people dont want to pay.

    same time, as the pipes get lower in rpm, they get longer in length. 1.2 metres for 6000rpm!

    easiest place is to continue bend around so it wraps right round frame and yes, does pop out on the left again...
  6. Fabian

    Fabian Well-Known Member

    Jaguar, can you then design a compact expansion chamber like the stacked pipe arrangement as i have shown in a prior post, because many of us have concerns about the law and having a large and obviously visible motorcycle style expansion chamber on a bicycle, which makes it look much less like a bicycle and more like a motorcycle.

    A compact expansion chamber that in some way resembles the standard exhaust pipe and muffler would make it less obvious to the long arm of the law.

  7. jaguar

    jaguar Well-Known Member

    Why don't you just buy the pictured one? I have no idea of the internals and so I couldn't duplicate it.
    If you don't want an expansion chamber then just extend the header of a standard exhaust 5 or 6 inches for more torque.
  8. Fabian

    Fabian Well-Known Member

    Because it is designed for a 15cc engine running at an operating speed of 15,000 rpm. It's length is only 15 centimeters.

    A conventional tuned pipe for this style of engine is aprroximately 3 - 4 times the length of the Muscle pipe.
    The innovative stacked design makes a tuned pipe significantly more compact.

    With your knowledge of pipe design i am sure that you could make an equally compact design for the 69cc engine, making installation of the pipe not only more practical but less (visually) obvious to the law; a point to make note of for people living in an environment that crucifies those who use an internal combustion engine in their bike.
  9. jaguar

    jaguar Well-Known Member

    It just isn't humanly possible to make an equivalent expansion chamber in that size.
    Anyway the cops don't care what pipe you have on it as long as it isn't too loud. They care about engine size, max speed, lights, etc.
    Please send me a text message if you want to persist on this wild idea of yours that can't work.
    I guarantee you that bomb at best just has a diffuser cone in it, one that is too short. It is more of a muffler than anything.
  10. Fabian

    Fabian Well-Known Member

    I guarantee that you are wrong.
    Curtis Youngblood is a world R/C helicopter pilot and has won many championships using his own designs and products. It might add weight to his results considering that he also happens to be an engineer, and non of his products are designed to offer less performance than any of the other market leading products.

    I can't see why the (compact) stacked pipe principle is not able to be scaled up to the size of a standard 2-stroke exhaust/muffler system, not to mention it would be a much more user friendly to install and has the added benefit of avoiding the potential of contact burns between your leg and a conventional tuned pipe.

    At very least it should be something that you can experiment with, given your knowledge on the subject.

  11. BigBlue

    BigBlue Active Member


    Have the perfect muffler for you to keep the police at bay:

    AKA: BigBlue
  12. HeadSmess

    HeadSmess Well-Known Member

    actually, what would be interesting is to be given the peak rpm of this torque pipe, along with relevant dimensions without having to modify the exhaust port, and ill run a simple demonstration by designing and comparing equivalent pipes using my expensive software results, my cheap software results, my freebie "superstitious caveman" software results, and jaguars excel torque pipe results, on a stock standard motor :)

    then may the answer be physically demonstrated, and the argument forever closed.

    im also keen to try any other design thrown at me :)

    this youngblood pipe. i tried to find a cutaway pic of it. good boy :) i can now sit here and analyse it a bit... im not so inclined to just throw the idea away, ive seen plenty of aircraft exhausts. that isnt quite normal.

    strangely, it stems from the feeling that the rounded end is a parabola, with its focus point approximately at the end of the internal tube... on the short fat one, at least. the other one just looks standard really.

    curtis youngblood has what many of us possibly dream of...unlimited funds. factory sponsoring. fancy gizmos to test everything with, every idea. and marketing geniuses if the product doesnt work too well in the end! :jester:

    firstly, i reckon make a model and put it in a ripple tank. watch wave propagation.

    ill make you one, scaled up. what will you pay?

    ill still say its not a true tuned pipe, but im sure it has something over a standard muffler/chamber...

    note. an expansion chamber is just a chamber of any dimension. a tuned pipe is TUNED.

    :toetap05: totally hi-jacked :toetap05:
  13. Fabian

    Fabian Well-Known Member

    I am sure we can come to some sort of agreement for the :beta1: version :smile:

    The stacked pipe arrangement will have to (in my application) exit on the left hand side of the bike and be able to clear a 2" frame down-tube.
    From what i can see the pipe would need to have the option of a secondary mounting tab to be able to tie it back to the frame just in case resonance proves to be excessive for the two exhaust studs.

    I am sure that a well designed stacked pipe could offer significant improvement over the standard muffler yet give much more stealthy appearance than a conventional tuned pipe as well as reducing noise.

    R/C helicopters typically operate in the 15,000 rpm band and due to the nature of helicopter operation they run constant rotor speed which required the engine to run at constant rpm, hence all of the performance pipes are designed to provide optimal power at a tuned rpm zone.
    I can't imagine Curtis Youngblood designing his Muscle Pipe to make less power than his competitors products and i would imagine that a well designed stacked pipe concept (at very least) may provide some of the benefits of a tuned pipe with much better packaging.
  14. jaguar

    jaguar Well-Known Member

    HS, I wish you would make a torque pipe. Then you'd see its advantages over a normal pipe and maybe produce them for others. I was toying with the idea of having the local latino welder make them but getting these latinos to work is like pulling teeth.
    Last edited: Jun 18, 2013
  15. Fabian

    Fabian Well-Known Member

    Jaguar, i completely agree with the notion of making a proper torque pipe, because it would be beneficial for those people who can get away with having such a pipe installed on their bike, and i wished that i was in an environment where i could have that kind of system installed on my bike.

    Unfortunately many of us live in environments where the law persecutes people who ride a motorized bicycle, hence a more compact, less visually obvious pipe is beneficial to that sector of the motorized bicycle community.

    Ideally it would be a great thing to have both: an optimally designed torque pipe (long version) and a compactly designed torque pipe for purchase.
    Last edited: Jun 16, 2013
  16. jaguar

    jaguar Well-Known Member

    A standard pipe with a 5 or 6 inch header extension is the po-boys version of a torque pipe.
  17. HeadSmess

    HeadSmess Well-Known Member

    i use MH aerotools, freebie, has reasonable but not spectacular results. i looked on from there. strangely, it still uses the same basic calculations outlined by blair and bell, that are standard practise nowadays... it has bugs. mainly in the cone layouts it produces, rather than effectiveness. and being single stage, its rather limited in performance gains.

    2 stroke wizard pro. i actually prefer its results to slightly costlier ones. shame i tried it last.

    MOTA. meh. for value for money, wizard pro wins.

    TSR. just freaking confusing and way too involved unless youre really into racing and i should have saved my money. oh well.

    i had another one but it was on another puter and vanished. it wasnt worth reregistering.

    and theres this one im yet to try! another freebie.

    ill make a torque pipe if you calculate me the dimensions for a 48cc with no modifications, for a comprehensive evaluation.

    just give me the rpm it will produce peak power, and ill design the same :)

    but, for some reason, even when using freebie software, im getting results that tell me there no point going for more CC or changing anything else? they maynt be at the ballpark, but they must have live feed coming over cable or summink.

    the reason i invested in software was because i have been making pipes on karts and bikes for a few years now. i didnt start on a pushy.

    i fiddle with pipes now, not in the search of more power, but in the search of a simple, cheaply produced design that works and suits 90% of bike frames. power is no issue.

    our thread? our own thread?

    hows about pipe bomb? power in a small tin :)
  18. HeadSmess

    HeadSmess Well-Known Member

    well, look at that...

    i have had my thinking cap on.

    i maded a drawing :)


    hopefully its displayed correctly.

    its not to any particular scale, its just a diagram, the measurements are a byproduct. surprisingly good though :) maybe just try it out as is!

    so, im contemplating that the end of that first "header pipe" is best shaped as a parabola.

    the end of the internal tube is placed at this focal point.

    this way, the positive wave travelling down the header from port, is focussed to a point, and the subsequent positive reflected wave is confined to the internal tube. the negative wave reversing and sucking exhaust out from port.

    positive wave then travels down this internal tube, encountering some divergence to keep the negative wave building.

    now, experiments will prove me right or wrong... a parabolic end opposing the internal tube, which reflects wave back, but up the external tube. these encounter the end of the chamber, which i feel is best flat but possibly tapered. not parabolic. this larger chamber acting much like the belly.

    the wave reflects, returns to the lower parobola, reflects and is once again confined to internal tube where it intensifies.

    emerges from end of tube, reflected, travels back into header raising pressure.



    refer back to diagram.

    critical dimensions i hopefully listed :)

    any others, please mention.


    i propose, firstly, a simple ripple tank test. i make a simple model from some styrene sheet in a plastic tub. experiment with angles and shapes for perfect wave transfers, if any :)

    two dimensions gives a good idea of wave propagation inside a tube, albeit at reduced speed.

    it does give a visual representation, and therefore an understanding of the internal action of this design.

    one concern is the main header from engine enters at right angle. the ripple tank will prove/disprove this.

    maybe it will need a real tight but smooth bend directy to the internal tube, obviating the external tube.

    theres the possibility of an elliptical end being used, with the property of being able to focus the wave "over there"...

    ie, the external "header" tube is ovalised, with the internal tube and internal header side by side.

    an ellipse has two focii, so the wave can be focussed from one tube to the other. (im not too sure about this bit... theory only... seems to work in concert halls?)

    so, figuring out the maths.....

    yee gods, i havent even started thinking that far! prove the concept with a simple model before proceding!

    i know some of the basics may apply. possible divergences in tubes, etc.

    reflection points hence curves of parabolas, which govern certain diameters/lengths. i really do feel the focal points play a major role in effectiveness of this design, if any.

    lengths. speed of sound, temperature and density/pressure.

    stinger/bleed placement...

    i do feel, that, if this pipe is doing what i picture its doing, it should actually do something!
  19. HeadSmess

    HeadSmess Well-Known Member

    Fabian likes this.
  20. HeadSmess

    HeadSmess Well-Known Member

    Fabian likes this.