Optimal operating RPM for engine

Discussion in '4-Stroke Engines' started by WENSIAW, Jun 10, 2009.


    WENSIAW New Member

    My Robin EH025 engine has a max output at 7,000 rpm and max torque at 5,000 rpm.

    What would be the optimal operating rpm for max balance of power, torque, fuel consumption and durability? Is it 5,000, 7,000 or somewhere in between?

  2. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    These are bulletproof little motors and you are obsessing way too much....
    I have a Robin EH035 and I ride it around at high revs most of the time, I don't worry about any of that stuff

    Just listen to the engine where it sounds most comfortable
    Change your oil and keep your air filter clean and it will last a very long time

    Peak torque at 5000 rpm would be your answer
    Look on the makers website
    Last edited: Jun 10, 2009
  3. stude13

    stude13 Active Member

    that is built to rev. it was built as a utility motor.
  4. Happy Valley

    Happy Valley Active Member

    The manufacturers curve peak HP at near redline rpm and it will be screaming at 7k.
    Conversely, it's not good to lug these little motors at throttle loads too far below peak torque. I remember a saying from my motocross days where we said to "keep it up on the pipe", meaning staying in the power band and of course, that was with a transmission.
    With a single speed motorized bicycle that is usually overcome by pedaling.

    WENSIAW New Member

    Sounds Cool! Most Importantly It Is To Determine The Optimal Rpm For Max Torque And Power In Order To Determine The Gear Ratio That I Need For Climbing Steep Hills.

    Fuel Consumption And Durability Comes Second.
  6. Happy Valley

    Happy Valley Active Member

    Yes and a good question. I would estimate you might use 4500 rpm for your equation.
  7. Old Bob

    Old Bob Member

    Peak effiency is at at peak torque. Car makers gear cars to have engine rpm at or near torque at normal highway cruise speed.