Is it better for gas engines to run at a fixed speed?

Discussion in 'Mechanic and Repair' started by DieselDeere, Dec 16, 2003.

  1. DieselDeere

    DieselDeere LawnSite Senior Member
    from Midwest
    Messages: 411

    Is it better for gas engines to run at a fixed speed?

    NCSERVICE LawnSite Member
    Messages: 206

    depends on the engine type, and speed
  3. Tvov

    Tvov LawnSite Bronze Member
    from CT
    Messages: 1,157

    My understanding of the situation is that "straight" gasoline engines (four stroke) last longer running at a constant rpm. "Mixed gas" (2 stroke) run better and last longer when they are running faster and slower rpms (not a "fixed speed").

    Personally, I haven't seen a difference. Stay on top of your maintenance, and you should be fine.
  4. xcopterdoc

    xcopterdoc LawnSite Senior Member
    Messages: 752

    I would say, the fewer rpms you turn any engine, the longer it will last. The exception being at idle. So, if you dont need to run the ole weed wacker at warp 9 to cut that grass sprig, don't do it. How many hours any engine will last is based on how many revolutions it turns during any given hour. As long as the maintenace is done of course. I have worked on many industrial type engines where constant speed is the norm. I saw no differences based on anything else except rpms. The diesels and old large gassers lasted longer due to the lower rpms.
  5. DieselDeere

    DieselDeere LawnSite Senior Member
    from Midwest
    Messages: 411

    We have a generator with idle contol which will let the engine idle if no load is present, should this feature not be used? Why is letting an engine idle bad?
  6. criecke2001

    criecke2001 LawnSite Member
    Messages: 3

    Air cooled engines depend on the constant flow of
    a volume of air to keep the temp. within a safe range.

    Fan on the flywheel provides this flow but only when
    it is turned at the design rpm.

    Faster rpm more air,more air cooler engine, cooler engine
    longer life.
  7. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    It will not hurt your engine to use the automatic idle control. I did contruction before starting my own LCO and we used a lot of generators. The best generators were Hondas with AIC. They lasted forever.

    An engine's temps will stay low even at idle. The reason they want you to rev an engine when you're actually using it is because engines do get hotter when they work.

    If you had an infrared temperature sensor you would clearly see that when an engine is under load it gets very hot. Remove the load and it cools down almost instantly.
  8. DieselDeere

    DieselDeere LawnSite Senior Member
    from Midwest
    Messages: 411

    Thanks Richard, what does the 1st number mean below you post?
  9. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    That is your IP number. It is your "identifier" to the Internet. Web sites on the Internet keep track of who's coming and going and where you've been using that number in addition to the famous cookie.

    There are 2 kinds of IP addresses. Static and Dynamic.

    A static address never changes and is only assigned to your computer. Most ISPs assign a static address to any given customer. An example of someone who might have a static address who be a Comcast cable modem subscriber.

    Dynamic addresses are new numbers that are assigned everytime you log onto the ISP. An example would be a AOL subscriber.

    Don't be concerned that any old Tom, **** and Harry can see your number through the use of my signature line. Your number is only shown to you and cannot be seen by any other users here at Lawnsite.
  10. dishboy

    dishboy LawnSite Fanatic
    from zone 6
    Messages: 6,176

    I don't know if I can agree with everything I just read. I think it is ok to run a two cycle engine at high rpms as long as long as it is not running lean since that also leans the amount of oil lubing things. I have run my machines seven to ten years and never seized or ruined a crank. The rest of the machine wore out. It may in fact be harder on them lugging, don't know because the idea is to get done fast as possible so I guess I'll never make that test. The idea that a engine runs cooler faster I would question also because it is also creating more heat. Everytime it fires; that's heat. I do age all these engines run cooler unloaded, I always cool down my machines at idle until I hear the rpms drop off a little.

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