efficient expansion chamber silencing

Discussion in 'Performance Mods' started by jaguar, Jul 14, 2012.

  1. jaguar

    jaguar Well-Known Member

    If you have ever listened to an expansion chamber unsilenced you would swear that they were designed to increase the exhaust noise as much as possible, and you wouldn't be far from the truth. The area of the stinger is usually around 60% of that of the header so the exhaust pulse is compressed as it goes through the stinger. Its exit thereof is like a mini explosion as the compressed gas rapidly expands into the air. But even with the same stinger size you can let the chamber gases exit from the side of the belly for an incredible noise reduction because the exit is 90 degrees perpendicular to the rearward direction of exhaust gas pulse. That side exit alleviates the pressure in the chamber and so the "pulses" exiting there are not so pronounced.
    I just tested my exhaust system after relocating the stinger from the rear of the baffle cone to the side of the belly. That, in conjunction with my new design of silencer, results in less noise exiting the silencer than what I can hear from the cylinder. (I need to insert fin vibration dampeners.) This is as good as it gets for a high performance engine.
    I am in the process of making free construction plans for the silencer as I don't believe anyone would pay $60 for a silencer (which would be the price from my distributor).
    This design is an offshoot of the Russian silencer I have been bragging about. It works even better than mine but the inventor is waiting for a factory to buy his design.
     

  2. Fabian

    Fabian Well-Known Member

    Can you post photos of everything - why not make a video as well!
     
  3. jaguar

    jaguar Well-Known Member

    Here is a picture of it on my bike.
    7-12silencer.jpg
     
  4. Fabian

    Fabian Well-Known Member

    How does the muffler or silencer work - what are the physical specifications of the baffle geometry inside the rectangular box?
     
  5. jaguar

    jaguar Well-Known Member

    Here is a side view of the internal paths in the silencer. The shortest path snakes about a bit and as it is doing that it is allowed to expand into other chambers. With the belly stinger and this silencer I don't even feel sharp exhaust pulses coming out of the silencer. Relocating the stinger is actually easier than making the silencer and will give excellent results no matter what silencer you use. But the two together are super excellent. I don't know how long before I can have construction plans ready. Tomorrow I am doing testing of exhaust gas temperatures in relation to exhaust port heights of 2 different cylinders to see how much of a relation there is. All for use with my Excel file for designing an expansion chamber. Otherwise the designer has to buy a $100 meter and drill a small hole in the header to measure the exhaust gas temperature. Then I have to figure a way to incorporate the 3rd generation baffle return wave into the 1st generation to give a realistic view of the final return wave that will affect engine performance. Excel file programming is quite cumbersome but is resulting in nice graphics that let you see the strength and shape of the waves returning to the cylinder.
    (This graphic of the silencer should say its length is 12cm, not 12mm.)
     

    Attached Files:

    Last edited: Jul 15, 2012
  6. Fabian

    Fabian Well-Known Member

    Excellent work Jaguar - i want to see more of your innovative experimentation :likelots:
     
  7. jaguar

    jaguar Well-Known Member

  8. Fabian

    Fabian Well-Known Member

    Can you please attach photos of the internal components of your silencer on your website.
    Although the information presented is good, it's a bit confusing when looking at the plans.
     
  9. jaguar

    jaguar Well-Known Member

    I will if I make another. Right now the only one I have is on my bike and it's sealed at the edges with JBWeld and is painted and so I don't want to take it apart to take pictures.
     
  10. Fabian

    Fabian Well-Known Member

    I think that we all look forward to you making another silencer and taking photos of the internal components, but the best option would be to make these silencers available for purchase, either through your website or through the JN Motors website.

    I really want one of your silencers!
     
  11. jaguar

    jaguar Well-Known Member

    The problem is that SBP sells a silencer for $9 and if JNMotors sold my silencer it would retail for $50-$60. So I gave up on the idea of making/selling it.

     
  12. Fabian

    Fabian Well-Known Member

    Why is that a problem?

    I have bought three of your Jaguar CDI's (for myself and friends) and would happily pay double the price if it came with the extra features that i want.

    I would also be happy to pay $50 or $60 for a silencer that works to perfection making the engine virtually silent without reducing power.
     
  13. jaguar

    jaguar Well-Known Member

    Well you are definitely in the minority. It took 3 months to sell one torque pipe. What conclusion do you think I got from that experience? Only reason my CDI is popular is because it is an item that is almost essential to this engine.

     
  14. Fabian

    Fabian Well-Known Member

    With motored bikes effectively become illegal just about everywhere in the western world, more and more people will have the need to ride almost silently under the radar.

    I am happy to credit your account with a Paypal funds transfer if you manufacture this new generation silencer.
     
  15. jaguar

    jaguar Well-Known Member

    My main business is in the alternative health field and I can tell you that what the intelligent logical person sees as essential is very different than what the common man thinks.
     
  16. Fabian

    Fabian Well-Known Member

    I am happy to credit your account with a Paypal funds transfer if you manufacture this new generation silencer.
     
  17. jaguar

    jaguar Well-Known Member

    You are the only person requesting this so far. It would take many more before I invest my time and effort into training someone to make them. I sure don't have the time.
     
  18. jaguar

    jaguar Well-Known Member

    Well, I bought a decibel meter (dbc) and measured my belly stinger pipe with and without my stealth silencer the same way the AMA reads them, 20 inches away at a 45 degree angle. Readings were 89 and 91db. So...
    91db has 16% the noise level of a silenced motocross bike (99db)
    89db has 10% the noise level of a silenced motocross bike (99db)
    So the belly stinger design reduces noise by 84%, and my stealth silencer reduces noise by 37%. Obviously if you want a quiet ride, and you have an expansion chamber, then you need to convert it to a belly stinger design. How? Cut off the stinger at the end of the baffle cone, weld that opening shut, drill a hole in the belly of the pipe (12mm for 48cc and 14mm for 66cc), cut out from sheet metal a "channel" and have it welded to the side of the pipe starting at the hole and ending side by side at the end of the baffle cone, then weld the original stinger to the end of the channel.

    ps- decibel does not relate to the power ratio of the noise directly. A reduction of 10 decibels means the noise is now 10% what it originally was. I used the calculator at http://www.sengpielaudio.com/calculator-db.htm to figure out the equivalent energy quantities of each decibel reading to come up with my percentage figures.
     
    Last edited: Jul 31, 2012
  19. vermhot

    vermhot Member

    Is that a pipe that you welded on your pipe belie to put on that silencer ???? And How long is the pipe and dose it matter the length of it ??? Did you Have a diameter of the pipe also !!!! Sorry alot of questions !!! I'm going to make another one ,had fun making the first so I want to do it like yours !!!!!!
     
  20. Fabian

    Fabian Well-Known Member

    You do not need to train someone to make the silencer.
    Just make the pipe yourself and i'll be happy to purchase it and credit your account with a Paypal funds transfer.
     
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