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Discussion in 'Off Topic [BG]' started by merlin, Nov 26, 2002.

  1. Small Explosion

    73 vote(s)
  2. Controlled Burn

    15 vote(s)
  1. Alrighty i need everyone's help here. Even if you dont reply but just vote that'll be sufficient.

    At rehearsal last night, my guitarist and drummer got into a heated discussion about "Is it a controlled burn or a small explosion that drives the pistons in a combustion engine?"

    My drummer said it was a controlled burn as mentioned to him by his mechanic. My guitarist the ever up coming scientist explained that it is a small explosion resulting when petrol is ignited under pressure etc.

    I am the third party on this and they asked me to research it because they have put a bet on it. :rolleyes:

    So yeah? what is it?


  2. lesfleanut

    lesfleanut Guest

    Sep 25, 2001
    Syracuse N.Y.
    Its more of a controlled small controlled explosion. :D
  3. Secksay

    Secksay Guest

    Sep 6, 2002
    New York, NY
    it's definitely a small explosion of the controlled kind. a burn wouldnt cause the kind of sudden force needed to drive the pistons downwards. although, the 'explosion' is merely high pressure fuel being burned at a high rate, so its kind of a burn too. hah.

    just tell him is an explosive burn, that'll settle it ;)
  4. Nick man

    Nick man

    Apr 7, 2002
    Tampa Bay
    Im pretty sure they are technically the same.

    The only difference I can think of is that an explosion in the way that we think of it is a rapid sudden burn.

  5. Nick Gann

    Nick Gann Talkbass' Tubist in Residence

    Mar 24, 2002
    Silver Spring, MD
    Think of it like this...

    If someone burns a piece of paper on the sidewalk, it exerts no force on the surrounding objects. An explosion however exerts force. Think of a grenade. It can shoot a piece of metal many many many yards away at a high speed.

    A piston is moved by a force being exerted. So it is an explosion, not a burn.
  6. Secksay

    Secksay Guest

    Sep 6, 2002
    New York, NY
    yeah, thats pretty much what I was saying. Most people associate explosions with uncontrolled events. if you really want to get technical with the terminology, an explosion is:

    a large-scale, rapid, or spectacular expansion or bursting out or forth

    Gasoline that is burned at an ordinary rate is what we think of when we think of 'burning'. Ignite gasoline at high pressure, and it merely burns faster, resulting in a 'spectacular expansion'. An explosion can really be anything, from rapid burning, to high air pressure or water. (ever explode a hotdog in the microwave? :D)

    I have my father to thank for all this useless knowledge. Hes a chemical engineer, with a speciality in combustion.
  7. kazzles


    Nov 23, 2002
    new york
    After reading the responses..I agree that its a explosion. Otherwise, I have no idea what the answer is! :D Gotta heart me! ;)
  8. Tsal


    Jan 28, 2000
    Finland, EU
    Small explosion, forcing the piston to move.

    Now, my consultant fee is 10% of the winnings :D
  9. D. Funkalicious

    D. Funkalicious

    Sep 22, 2002
    Small explosion...spark plugs ignite the fuel/air mix after it is compressed by the piston. The resulting explosion forces the piston down and starts the cycle all over again. If it burned at all, the performance of the engine would suffer.
  10. ldiezman


    Jul 11, 2001
    a small controlled explosion... yeah thats it
  11. lneal


    Apr 12, 2002
    Lee County, Alabama
    It is a controlled burn, NOT an explosion. As the piston goes up on the compression stroke, the fuel/air mixture is compressed into a small area that is about 8.5 times smaller than when it entered the cylinder. When the piston reaches the top of the cylinder the spark plug then ignites the mixture, and if all is functioning properly, the mixture burns evenly across the top of the piston. It is not an explosion that creates the power, rather the expanding gases caused by the burn that forces the piston down in the cylinder.

    Yes, I was a hot rodder and have all this useless knowledge that I need to share.
  12. Tsal


    Jan 28, 2000
    Finland, EU
    And this is not an explosion because... ? :)
  13. Hategear

    Hategear Workin' hard at hardly workin'.

    Apr 6, 2001
    Appleton, Swissconsin
    It's a quick, controlled burn (I've turned wrenches on both automobiles and motorcycles).


    EDIT: The fuel/air mixture is (usually) ignited just before TDC, which helps force the piston downward. The fuel/air mixture is ignited by a spark, not by the pressure exerted on it by the piston.
  14. bplayerofdoom


    Aug 6, 2002
    im not a mechanic but i am a rocket scientist. Its an explosion. (yes us rocket scientist have time to sit on comps all day and play bass too. I mean come on, its only rockets.)
  15. neptoon

    neptoon Supporting Member

    Jul 25, 2000
    Melbourne, FL
    ahhhh.....detonation verses deflagration. i dig this stuff. what causes a piston to move is the expansion of gases from the burning, or deflagration, of the gasoline on the face of the piston. cylinder volume, blah blah blah is really no big deal, because then you get into compression ratios and a whole bunch of upper end valve stuff. detonations, or explosions, occur when the reaction between reacted material and unreacted material occur at velocities at or greater than the speed of sound and create shockwaves. wouldn't that suck? to hear thousands of shockwaves breaking the sound barrier in our engines?
  16. neptoon

    neptoon Supporting Member

    Jul 25, 2000
    Melbourne, FL

    ahhh, the dieseling effect....or compression/ignition...in it's truest form, _that_ actually is an explosion, but in automobiles, we have glowplugs to help the reaction along to keep from blowing our engines up.

    i ain't a rocket scientist, but i am a missile technician (really...no s**t). second best thing, ya know ;) now, say it slow....can we all say cyclotetramethylenetetranitromine? :D good, i thought so
  17. neptoon

    neptoon Supporting Member

    Jul 25, 2000
    Melbourne, FL

    sorry, but i've got beef with that...
  18. Hategear

    Hategear Workin' hard at hardly workin'.

    Apr 6, 2001
    Appleton, Swissconsin
    Dieseling sucks -- bad!
  19. neptoon

    neptoon Supporting Member

    Jul 25, 2000
    Melbourne, FL
    you're right, it does...i have had experience with it onboard submarines. mixing an oily pipeline with 4500 psi air ain't cool...trust me. it makes BIG badaboom
  20. This is great people! Although its starting to sound like band practice with the "yes it is, no its not" arguements...



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