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exhaust flame thrower

Discussion in 'Electronic Basics' started by ngdbud, Jan 8, 2006.

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  1. ngdbud

    ngdbud Guest

    Could I make a simple exhaust flame thrower for my mini bike without a
    $100 kit? I'm thinking of just putting in an SPDT momentary rocker
    switch (if there is such a thing) that can redirect the electricity
    from the engine to a spark plug in the exhaust. The kind of switch I
    would need would be switch that is always on in one setting and then
    springs back after I press it to a different setting. Do they make

    on (except when pressed)

    --------------_____------(> engine spark plug
    switch -------(> exhaust spak plug


    If that makes any sense.
  2. Tom Biasi

    Tom Biasi Guest

    Do a search for a SPDT momentary contact rocker switch with a 15,000 volt
  3. Are you looking for a bloody great backfire from the exhaust pipe or do you
    really want a flame thrower?

  4. Jasen Betts

    Jasen Betts Guest

    you'd need a switch that can switch the thousands of volts that go to the
    spark plug. you could possibly use an autombile disttributor.

    you'd need to attach a lever to the input shaft to to turn it sufficiently
    to switch to the other plug.
  5. steamer

    steamer Guest

    --Funny you should mention this. Last weekend, I think it was
    on Spike TV on one of the truck shows they showed how to do this. You
    might snif around over there. I'm planning something similar for an art
    car project. Another place to ask would be over at in one of
    the pyro or art car tribes.
  6. Rich Grise

    Rich Grise Guest

    It's doable, BUT!

    Yes, there are momentary rocker switches, but you wouldn't want SPDT,
    because then your motor wouldn't fire.

    But the real problem is switching the 15-25KV spark voltage. The
    spark would happen in the switch. What you really need is another
    coil, and a free-running sparker, that you energize with your
    rocker switch.

    If you haven't been an electronics nut for a year or more, then it'll
    be cheaper to buy one, if you can get one for a hundred bucks.

    Good Luck!
  7. Rich Grise

    Rich Grise Guest

    I sit next door to a performance shop, and if OP thinks he can do this
    for less than $100.00, he's in dreamland.

  8. ngdbud

    ngdbud Guest

    Thats exactly the show I saw that set me on this path. I checked out
    the kits he was talking about, there $100 daollars. That sounds like
    way too much money just for a kit to divert electricity from an engine
    coil to rear coils. There maust have been some sort of driver involved
    with the kit, but still, it shouldn't cost that much. I saw that show
    just before going to a supercross event with Bubba Stewart, Ricky
    Carmichael, Jeremy McGrath, Chad Reed, every body. It was so cool.
  9. ngdbud

    ngdbud Guest

    Depriveing the engine of power is the only way this works. Without a
    spark a perfectly measured air fuel mixture is sent through the exhaust
    pipe to be burnt near the end of this journey. Your supposed to rev the
    engine up to a high rpm and press the switch. Momentum will keep the
    engine going long enough to get a good flame; so if you can shoot
    flames for about a second to keep the engine from stalling (at least
    for a minibike like mine, for a car you could go longer). I had a
    course for a couple of weeks in small engines. There electrical system
    works a magnet IN THE FLY WHEEL being sent past a small coil to
    generate the high voltage, so yes, the first spark would be lost in the
    switch but each spark after would light it up.
  10. ngdbud

    ngdbud Guest

    A side thought, what if youwere doing this with a v8 engine. could
    power be cou to just 4 cylindars and have them pump gas while the other
    four run the engine so you can get a continuos flame?
  11. JeffM

    JeffM Guest

    if OP thinks he can do this
    On a 40-year-old car with a carburator and Kettering ignition
    it would be duck soup.

    Rig a pull-choke
    (maybe $4; $0 if you have an old lawnmower for parts).
    Add a 2nd ignition coil (maybe $10--less from a junkyard).
    Rig a SPST switch that cuts primary juice from the main coil
    and diverts it to the tailpipe coil.
    (The points are hooked to both coils.)
    Mount the 2nd coil near the tail pipe
    so the high-voltage lead can be short.
    (1 ft of used spark plug wire: $0)
    (Used spark plug: $0.)
  12. Jasen Betts

    Jasen Betts Guest

    if the motor fires there's no fuel going into the exhaust.

  13. If anyone not familiar with this device is interested in seeing and
    hearing it in action, go to this web site:
  14. cbm5

    cbm5 Guest

    I used to think that putting a 4-inch exhaust cap on 1.5-inch pipes from
    a 1.6 liter engine was the epitome of mental retardation, but at least
    that wasn't dangerous.

    I nearly choked on my lunch seeing the photos of that miserable Honda
    Civic. Not satisfied with merely installing fart cans, these "gearheads"
    are now LIGHTING the farts.

    The first time someone singes my grille, I'm ramming.
  15. Rich Grise

    Rich Grise Guest

    But why do you want to cut the juice to the motor coil? You
    want your motor to quit while you're trying to blow flames
    with its exhaust?

  16. JeffM

    JeffM Guest

    why do you want to cut the juice to the [engine's] coil?
    Someone else already mentioned rotational inertia.
    (Actually, you don't push in the clutch.)
    You want the fuel/air to get thru the engine UNBURNED.
  17. Alan B

    Alan B Guest

    Precisely. If the OP's mini-bike has a carburetor and an engine kill
    switch, he needs no mods. While riding, kill the ignition for a
    second or two, blip the throttle, and re-engage the ignition. Kaboom!
    Now of course, the reduced lifetime of the exhaust system must be
    considered as part of the overall cost. :)
  18. Alan B

    Alan B Guest

    Yeah, you can put another coil and spark plug in the exhaust, but that
    will do squat. The exhaust is hot enough to ignite combustible
    material without a spark helper - the spark would really have little
    effect at all. What you need is unburned fuel in the exhaust.

    Probably (I'm guessing here) the flame-thrower show mods are a fuel
    sender to a combustion chamber attached to the exhaust. Separate fuel
    lines, separate coil, separate fuel injection system. Hunnert bucks,
    yeah, that oughtta do it! :)
  19. Alan B

    Alan B Guest

    Ramming is soooo immature. Sue the bastards.
  20. Rich Grise

    Rich Grise Guest

    I've seen these - right next door, there's a "performance shop", and
    I occasionally see this very thing on some show car or another.

    I think "a hunnert bucks" will get you about 1/8 of the system or so. ;-)

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