diesel questions

Discussion in '1982-Present GM Diesel' started by unick, Dec 10, 2003.

  1. unick

    unick 1/2 ton status

    Aug 16, 2003
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    San Diego Comufornia
    Whats the difference beteen a gas and diesel engines? I know the fuel is different and a diesel has glow plugs insted of spark plags. Is there anything else?

  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Jul 23, 2000
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    E-town baby!
    The diesel engine uses nothing more than compression for ignition. It uses a mechanical injection pump that injects the fuel into each cylinder at extreme pressures. The timing of each 'injection' event is akin to a spark plug firing on a gas engine.

    Glow plugs are only used when a diesel is cold, it provides a glowing heat source to aid in ignition, and is only needed for start up. Once it's running the glow plugs aren't used.

    Diesel engines don't have ignition systems. They also don't have any throttle plates, in fact the intake is wide open and large enough to inhale a cat (OK, a small cat...) A diesel will run just fine with no intake at all, but it would be difficult to filter the air that way.

    Diesels use much higher compression ratio's than gas engines. Typically above 18:1, although the 6.2 uses 21:1 for easier starting.

    Contrary to popular belief, the 6.2 was not derived from any previous gas engine built by GM. Detroit diesel designed and built it from the ground up for GM.

    Lastly, diesel generally make a ton more torque at the lower rpm's and also use fuel much more efficiently than gas engine. All things being as equal as they can be a diesel will generally get 70%-100% better fuel mleage than a gas engine.


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