Do Yoy really need to run at full throttle?

Discussion in 'Lawn Mowing' started by Beckham, Jun 12, 2007.

  1. Beckham

    Beckham LawnSite Member
    Messages: 30

    First let me tell you I'm not in the business just enjoy reading the discussions about the machines. Keep up the good work! I come from the old school (read age here) where you use enough throttle to get through the grass you were cutting. Thus more throttle for higher grass and less for lower grass might even go down a gear (pre-hydro here) for the heavy stuff and stay at the same RPM. Thats the way we were taught, saving engines and fuel economy and such. I know they now say open her up......cut wide open, the engine cools better, you get a better cut etc. It just seems that you guys that have high HP machines or larger machines with the diesels would not need to run with the throttle wide open. Lots of those engines are water cooled so cooling shouldn't be an issue at most RPM's. Max torque is very seldom made a high RPM especially in those diesels! Do you guys with those engines peg them to the max and head out for a days work or is there a happy medium somewhere?:confused: :confused:
  2. cantoo

    cantoo LawnSite Silver Member
    Messages: 2,910

    The pumps need to run at the correct speed and as far as I know this is usually full throttle. I know my Steiner whines if it is run below half throttle. We usually run them wide open to keep blade speed as fast as possible.
  3. LindblomRJ

    LindblomRJ LawnSite Silver Member
    Messages: 2,570

    Yes, blade speed for quality of cut and cooling on an aircooled machine is important. These engines are designed to run at high speeds. Both gasoline and diesel.
  4. 02DURAMAX

    02DURAMAX LawnSite Gold Member
    Messages: 3,801

    Is this your first post since July 2004??

    oh and yes they need to run at full RPM..
  5. cantoo

    cantoo LawnSite Silver Member
    Messages: 2,910

    02DURAMAX Is this your first post since July 2004??

    oh and yes they need to run at full RPM..

    He didn't want to speak out of turn.
  6. LindblomRJ

    LindblomRJ LawnSite Silver Member
    Messages: 2,570

    LOL. At least its not a question that gets asked 50 times a day.
  7. 02DURAMAX

    02DURAMAX LawnSite Gold Member
    Messages: 3,801

    well then i guess he won't be posting here again for another 3 years..:rolleyes:
  8. tacoma200

    tacoma200 LawnSite Fanatic
    Messages: 5,426

    How many times have I heard that you need to idle the engine a while to "cool" it down before shutting it off. So that would seem to contradict the WOT is needed to cool an engine.

    I personally don't know if idling cools one down but that's what I've always heard. Throttle down on the way back to the trailer and let it run a while a low rpm to cool the engine before shutting it off.

    Just wondering why there are two schools of thought here. I run mine at lower than WOT at times such as when I'm not wanting to discharge as far (around beds) or in wet grass the lower blades speed seems to help. Exmark told me it wouldn't hurt them to run at less than WOT.

    Can't say I'm sure.
  9. KS_Grasscutter

    KS_Grasscutter LawnSite Gold Member
    Messages: 3,336

    An air cooled engine is going to have more air flow at WOT, thus helping it cool down better. Not sure on liquid cooled engines though.
  10. topsites

    topsites LawnSite Fanatic
    Messages: 21,653

    If I really open up my new 15hp engine, it literally turns the muffler red hot. And if I don't let the mowers idle for a good minute before shutting it down, they go Ka-BOOM as unburned fuel backfires out the exhaust. If I do it on the new engine, it shoots a flame out, kinda cool looking, like on a rice rocket, it's a short white burst.
    But, should I let it do that?

    I've ran machines both ways from new to crapped out... That is, either run it WOT the entire time from the day you get it until you throw it away, or do it the other way (just enough to do the job).

    I personally see no difference in how long they last, I would think they last longer away from wot.

    I usually run WOT when I've got the area to do it in, but if I'm not in that much of a rush, I like 90% throttle (which is, back it off full until the rpm's just want to drop, right before they drop, that I call 90%)... It seems to save fuel.

    The Z has hydros, those need power.
    But the gear drive fixed deck has plenty of rpm's, even at 1/2.

    I turn down rpm's near the house and vehicles, also when the chute has to face the street or the house, around people and animals as well, and when I run in 4th gear instead of fifth, I use less throttle as well.

    With the trimmers and blowers, same thing, just enough to do the job.
    It saves considerable fuel, I get 4-5 lawns on a trimmer tank during spring, 8-10 in the summer... The blower lasts 2-3 days on one tank, sometimes 4.

    Honestly, I think the thing about running it WOT is a saying because you can't go wrong telling Lco's to run Wot. Either way, running less than wot saves $ on fuel, I keep the Wot option open for hardcore work.

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