Muffler/Expansion Chamber - Making One

Discussion in 'Rack Mounted Engines' started by Hive, Dec 6, 2007.

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  1. Hive

    Hive Guest

    Okay! Not sure where to post this one, so will stay with similar drive type, though this may apply to other applications and engine types.

    It is 0 degrees F where I live, bike is hanging, motor is tucked in corner. Fishing is kaput. I would be hunting but too cold and not in mood. Besides, no respectable grouse or pheasant would be out in this weather, so, before I get into the darkroom, here is the plan.

    Construct a "muffler" or small expansion chamber for next season. All suggestions/critiques are welcome, particularly from those who have tried a similar project.

    Motor is 2-cycle T-3300 on GEBE rack system.

    Use a 3/8" copper elbow from exhaust pipe - it fits and is easily clamped tight after cutting slits in one end to secure;

    Attach high-temp silicone tube to the elbow;

    Connect that tubing to 6" piece of 2.5" PVC - the "chamber;"

    The "chamber" or muffler will be empty (as opposed to a holed out pipe or silicone and/or surrounded with SS wool inside)

    Exit end is .5 inch.

    Paint black.

    Fasten chamber downward to GEBE rack mount, redirect exhaust away from bike.

    Will this rig reduce exhaust noise and not harm engine or reduce efficiency?

    Last edited by a moderator: Dec 7, 2007

  2. Hmmmm...somebody else here used copper in their exhaust system....Can't remember off hand....their solder joint if you use copper have to clamp or use a spring system to keep it all together..sounds like you might be doing that since you mentioned the high temp silicone hose..As far as PVC and high temps....Not sure....but gut feeling is that it may melt?....I could be wrong tho but PVC is basically like a plastic....and probably not a high temp tolerant one at that...but if it is far enough downstream maybe the exhaust will lose enough heat so as not to melt it?
  3. Hive

    Hive Guest

    Copper Exhaust Failure

    That was moi. I assumed it would fail, but had to see how long it would take. Not long. I removed the thread, fearing someone would try it and have an accident ...

    The first connection melted and dropped the pipes. Just glad it did not hit a car, etc.

    That is why only copper will be first piece attached to engine pipe and no solder employed.

    May have to use copper instead of PVC for the chamber to gain a heat sink, but silicone will be employed and clamps will connect the components physically this time.
    Last edited by a moderator: Dec 6, 2007
  4. JemmaUK

    JemmaUK Guest

    When I set up the Exhaust extension on my old bike I used a .140 aero engine bend to connect to the exhaust port... that was fine regarding temperature...

    From what you have said about the plan so far it sounds good - it *might* given you will have created a stinger, provide a little bit of power boost but I'm not sure..

    Im curious about the performance of your engine. I just got the T3300 and as far as top end and fuel consumption I am not entirely impressed...

    Jemma xx
  5. kerf

    kerf Guest

    Tin based solders won't handle the heat close to the exhaust port but phosphorous copper brazing will. The melting temp is 1400 F, so you need at least oxy/mapp to get the job done. The rod uses no flux, just sweat as you would with tin.
  6. Hive

    Hive Guest

    Tin soler

    Yes, Thanks. I found that out the hard way. I will use a ss clamp to connect to pipe and then clamp silicone tube to that elbow and go from there.

    Sound good?

    All I have to do is acquire the silicone tubing.
  7. Haggard

    Haggard Guest

    Hi Hive . Your on the right track . Exhaust can make or breaka 2 strokes performance . I'm trying to think of the term I heard used.
    . Harmonic charger? Harmonic boost maybe?
    I've done an extreme amount of reserching aswell as hands on trial and error and while I cant tell you excactly what length , what width what degree etc ,No one can without having the actual motor in there hand , I can give you a good thorough understanding of the principles involved but be warned, once you delve into this misterious phenominom . It'll be spring before you know it!!. Keep an eye on the Mounting a pocket bike thread in rack mounts. I'll be doing a complete section on 2 stroke exhaust that i guarantee to answer all your questions : )
  8. Hive

    Hive Guest

    I Will

    Be looking forward to it.

    I right now I have concluded that the chamber, given the fact that the exhaust is just open pipe otherwise, it must be such that it does not create too much back pressure.

    Figure a 6-incher will do it, with a 2-inch diameter.

    Spring! I wish!
  9. Haggard

    Haggard Guest

    You can see a working model of a stroke expansion chamber on "my space"

    It demonstrates why the length of the header and the size and angles of the expansion chamber have to be directly perportionate to the cylinder size and port timing has to be taken into consideration aswell for ultimate performance

    Last edited by a moderator: Feb 13, 2008
  10. Hive

    Hive Guest

    Expanion Chamber

    Great video, Haggard. Thanks!

    I knew these things have a science behind them but decided not to get too big with extractor device, not going for speed.

    Planning to go with a gradually opening pipe diameter, so any restriction is minimal.

    Using .75 copper pipe I had laying around, may go to one-inch.

    The inside is 5/8", which is larger than the engine exhaust pipe. If 1" will use .75 inside pipe but make it shorter.

    The inner pipe will have lots of orderly drilled ports (holes) and is longer than the outer pipe, to accept the silicone hose from exhaust port.

    The inner pipe extends just a bit from rear of pipe with gaps around it to increase flow - decrease resistance.

    I was going to stuff area between two pipes with fiberglass roving, but may forget the roving in this first version or only fill one-half of pipe - a mini expansion chamber?

    The roving will deaden sound and not deteriorate and float away, according to the information on the "Swedish Exhaust Pipe" link for straight-through exhaust muffler on 4-cycle airplane power, here:

    May build second version with roving, if first causes problem or does not work and even third to experiment a bit just for fun.

    I wish to deaden sound a bit, without the bulk, and without hindering flow, which is why the larger pipe. Engine exhaust for is only 3/8". A 3/8 copper elbow is clamped with SS hose clamp and a silicone hose connects the elbow and the muffler.

    Will keep all posted with pics etc. but will likely begin separate thread on it, so look for it when I can test the device.

    Appreciate the video you linked - and other vids also. Thanks again.
    Last edited by a moderator: Feb 13, 2008
  11. Hive

    Hive Guest

  12. Hive

    Hive Guest

    I Just Figured

    Out something.

    The Tanaka 3300 and this and similar engines already have a built-in expansion chamber.

    All one has to do is quiet that gas stream with less back pressure.

    Voila! Make sense?
    Last edited by a moderator: Feb 13, 2008
  13. Hive

    Hive Guest

    Added Thought

    That I posted on another thread covering same topic: The Tanaka has a built in expansion tank, so I figure the pipe to just deaden some noise, if it works. If not, back to bare pipe. No big loss.

    Brent, your bikes impressed the heck out of me.

    Bet lottsa neighbors hangin' 'round your garage, right?

    The vidio link changed and Imiss the Asian exhaust in the lobby.

    And the great Len Cohen too! Love it!

    Am I in right league?
    Last edited by a moderator: Feb 14, 2008
  14. Hive

    Hive Guest

    Muffler/Expansion chamber - Sorta

    Okay, I am anal and could not let this sit, although there is 5 inches of snow on ground and temp this AM was 3. But, why not?

    Decided to try to stay small, muffler-wise.

    Pic shows following: 8 inch x 1/2" copper pipe; two 1" x1/2" connectors; one 1' connecting sleeve. (NOTE: These items were in bin with other 1x1/2 inch reducers (so bin label said) and some were a bit larger than these were,so I took those that fit INTO the 1" sleeve I already had with old fittings.

    The 1/2" pipe has a number of drilled ports in the center for the short option and will increase number of ports, if need to extend the device as in the long version shown. Short version is in middle, bottom is extended. Will be able to test without soldering etc, by moving outward as needed.

    Using silicone tubing from Dave's to connect exhaust to suppressor.

    The idea is to make a short/small suppressor/muffler, packing one end or not with roving, and testing, and gradually lengthen until satisfied with low sound and engine performance. Will trim ends at that point, if necessary.

    The Tanaka-33 exhaust is 3/8" and am guessing the resistance from 1/2 inch pipe to chamber will not be sufficient to reduce efficiency but will reduce sound and remain compact.

    Will likely hang/attach this below the engine from its cowling in some way, but will cross that bridge after I test to see if this cobbled muffler functions as intended.

    Attached Files:

    Last edited by a moderator: Feb 16, 2008
  15. Hive

    Hive Guest

    Clamp to Engine Exhaust

    With spring just around the corner, so I put this up, for early starters. but, might be better to wait and let me advise if it is worth the time, etc. Of course, if anyone wants to jump-start this experiment, have at it.

    This is Tanaka 3300, but I am thinking it will apply to 25s, 40s and 47s, but not sure. I use a 3/8th copper fitting elbow to go slip over the engine exhaust pipe.

    If Tanaka uses same muffler or exhaust for their engines, should be same. Regardless, if other engines are large, large fitting can be located, am guessing.

    Picture of hole that is needed to necessary to drill in engine cowling around exhaust port/pipe for screw driver to be able to tighten small ss clamp that secures 3/8 copper elbow fitting to engine exhaust pipe. Only has to be as large as screw driver head.

    The copper pipe's larger end is cut with 4 or 6 small slots, so it will tighten down on pipe, as the SS clamp is tightened around copper fitting. Will put that picture up later.

    With Dave's silicone hoses, should stay together, with silver solder only in the muffler component.

    Now, if it reduces noise, Voila!

    Home free!

    Attached Files:

    Last edited by a moderator: Feb 26, 2008
  16. Hive

    Hive Guest

    Need Your Opinion

    With the warm weather approaching, am thinking of putting engine/rack assembly back on bike and beginning my exhaust experiment, but need advice from those who know about such things.

    As you know, this "muffler" is for Tanaka T3300 2-cycle.

    The pipes used are larger than the engine exhaust port, to minimize any back pressure.

    The gases can enter and exit the mini expansion chamber in three ways:

    1. Essentially a straight-through device. Run the pipe straight through, as shown in above pics of copper muffler, with ports drilled in the pipe to allow gases to circulate in chamber before exiting.

    2. Same as above, but with fiberglass blanket around the pipe to absorb sound.

    3. Run gas into chamber but the pipe does NOT run straight through, letting gases expand and circulate, before exiting at other end...

    Looking for quiet, not added speed, without adding adverse back pressure.
    Last edited by a moderator: Mar 17, 2008
  17. vegaspaddy

    vegaspaddy Member

    hi hive,

    keeping a close eye on your thread, my t3300 was supposed to get here today but UPS doesnt have the right address, found that out threw the tracking link from gebe.

    Ah well one more day wont kill me
  18. Hive

    Hive Guest

    Muffler Parts and Assembly - Experimental Fun

    For the anxious ones, like me. We have 8 inches of soggy snow on ground, but...

    Here are two pics of the muffler parts and potential assembly, with explanations. NOTE: Has not been installed and tested to see if it actually does reduce sound level ... part of fun.

    1.) Clamps, SS, that secure system to engine cage - small one to cage, around spacer/shim piece, other to muffler.

    2.) Filler piece that rests against protective cage grille so clamp can hold without crushing cage.

    3.) Pencil points to copper connect pipe that will likely be silicone hose - need at least one section of hose so assembly can be removed.

    If 500 degree silicone hose is used at this point, use "fitting elbow, having one large end and one narrow .5" end, so hose slips over easily. I will likely use hose here also. Makes for easy adjustments, etc.

    4.) Hose to separate 3/8" elbow from assembly to limit heat affects and easier assembly removal.

    5. 3/8" elbow (with slits in connecting end) connects to exhaust port, and small SS clamp that holds the slit 3/8" elbow to exhaust port.

    6.) Outer section of muffler - .75" sleeve connecting .75-to-.50" reducers.

    7.) Through-pipe, with holes drilled for circulation and to allow gases to flow into chamber and/or by/through fiberglass covering - may omit, trimming at each end...have not decided.

    The second pic shows device assembled, though not soldered as yet. It will hang directly beneath the Tanaka protective cage, with longer exit pipe - may have to alter if dripping exhaust moisture/oil becomes a problem.Will extend to rear with hose if a problem to preclude messy bike/tire, etc...

    Still have to determine whether to run straight through pipe with holes and fiberglass or trim at each end inside of muffler section to let gases bounce about and flow out with minimal back pressure.

    Plastic tube is silver solder.


    Attached Files:

    Last edited by a moderator: Mar 22, 2008
  19. Hive

    Hive Guest

    Progress Report

    Progress report...

    Pics of soldered (silver) muffler, and approx engine positioning...need to paint etc.

    Will hang beneath cage using two hose clamps, one around pipe and one around two small pieces of pipe at cage to form grip area above and below cooling slots. Idea is not to damage slots and offer a stong grip.

    If it works, will extend pipe past fuel tank a bit.

    Will hold off painting until after test run.

    It snowed last night, with more coming. But, looks like a fifty degree temp coming in day or so.


    Attached Files:

    Last edited by a moderator: Apr 1, 2008
  20. Alaskavan

    Alaskavan Guest

    I hope this one works. I have stopped trying to invent one myself. I'll just wait 'till you perfect it, then steal your design. Assuming you won't mind. And thanks again for pointing me towards this site (seems like years ago).