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Prius Engine Sound in ECO zone

Discussion in 'Gen 3 Prius Main Forum' started by Roger T, Dec 27, 2014.

  1. Roger T

    Roger T Member

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    I am wondering, when the HSI in the ECO zone (after the mid line, before the PWR zone), how does your Prius gasoline engine sound like? Is it like a low humming sound? Or completely quiet?

    What about in the PWR zone? Do you consider it loud in the PWR zone?

    I noticed that some Prius are quieter than the others... My cousin's Prius has almost no engine noise... In the ECO zone it is barely audible (completely overwhelmed by the tire noises at any speed), in the PWR zone it is just slightly low humming...

    BTW, her tires in the Prius is always under-inflated, like 30 or 31 while the factory spec for her tires is 35 front/33 rear. Does it make a difference?
     
  2. CR94

    CR94 Senior Member

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    That's all very subjective, but my impressions as a novice Prius owner:
    If we subdivide into thirds the section of the "ECO" zone you describe as "after the mid line, before the PWR zone, " I'd say the engine is inaudible or nearly so in the left third except at very slow speeds. It's clearly audible in the right third. The engine seems surpisingly loud in "PWR," compared to my much older, smaller, and lighter car that preceded the Prius. However, that perception may be largely due to the Pruis being so much quieter in other respects.

    I was a surprised that acceleration of the Pruis is so leisurely (to put it charitably!) even near or inside the PWR zone.
     
  3. Roger T

    Roger T Member

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    Thanks for your reply.

    I have the same perception. At highway speed, it is barely audible at first third in the ECO zone, audible but still very quiet in the second third and third third in the ECO zone, very loud in the PWR zone, so loud when floored, sometimes i floored the gas just to hear it ;), which is a nice jet engine like loud humming noise. At lower speed (0 to 40 mph), the first half in the ECO zone is very low frequency humming, second half is louder but still low humming, the PWD zone is... loud.

    One of the Prius design principle is, use a small engine in an un-matching big car. In full power acceleration scenario, the electric motor in full power in a short period of time. But i am still surprised at how loud the gas engine would be under full throttle.
     
    #3 Roger T, Dec 28, 2014
    Last edited: Dec 28, 2014
  4. bisco

    bisco cookie crumbler

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    i'd say mine is a low buzzing in eco, and loud buzzing in power.
     
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  5. bisco

    bisco cookie crumbler

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    yes, the lower pressure is hurting her mpg's, but helping her ride comfort.
     
  6. jonb505

    jonb505 Member

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    In your cousin's prius are you by chance sitting in the passenger seat? Where you are sitting in the car could make the engine noise more or less noticeable.
    Perhaps the unpleasant engine noise in the pwr zone is another method the prius employs to train the the driver to drive more efficiently.
    Driver wants to go faster, pushes gas pedal down, hears loud unpleasant noise, backs off gas pedal, gets better mpg. :)
    The jet engine noise you hear at wide open throttle may also be the sucking noise of the battery cooling fan under the rear seat.
    The battery fan in my prius v goes full throttle almost every time when i put the pedal down to maintain speed up a local, short, 20% grade at 50kmh. Makes sense, the prius figures its a good opportunity to cool the battery while the gas engine makes lots of noise to distract the driver from the noisy cooling fan. Brilliant design, no? (y)
     
  7. Starship_Enterprius

    Starship_Enterprius Active Member

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    Depends on your driving style and whether you have a heavy foot or not.

    In the PWR zone even if it is all lit up, you can still floor the pedal and go faster and make the engine growl really loud.

    Within the ICE zone, it can be quiet or loud depending on the current speed you are going and how fast you got it up there.

    From a standstill, if you stomp on the gas without letting the electric motor move you from zero, then it will be noisy and labored without adding much to your speed. But if you first let the electric motor bring you to speed before letting the ICE kick in, then it will be a quiet and relaxed drive.

    From the EV zone if already moving if you force it up quickly to max ICE zone it will be noisy and labored. But if you respect how the Prius restarts the engine and work with that little bump when the engine comes in, then it will be a much quieter and more relaxed ride.

    At highway with the ICE already on, working on momentum and depressing the gas only slightly and respectfully waiting for it to bring you up to speed a la rubber band style will give you a much quieter accelerations.

    The last one is the trick on how to keep you engine quiet on any car. Just depress the accelerator lightly and consider that a suggestion (instead of a command) then wait for it to get to speed. Soon enough you'll know how much sooner you need to do that in anticipation of road conditions ahead. Its gets so you can start pressing on the pedal a few seconds ahead most other cars just to keep up with traffic rubber band style while keeping the engine happy.

    I do this even with our Sienna minivan and my Dad and other passengers often remark how powerful the engine must be because they never heard it scream or labor even fully loaded. Not realizing its how i respect the engine and always try to keep it at it's best power zone. I also get way above EPA mileage with it.
     
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  8. GregP507

    GregP507 Senior Member

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    Underinflation isn't a bad idea in the winter if you have traction problems. Some trucks in Russia have tire-pressures that can be set on-the-go, in accordance with terrain conditions. I think I've heard of it being used elsewhere as well.
     
  9. css28

    css28 Senior Member

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    Many military trucks also have central tire inflation systems.

    They're integrated in such a way as to prevent highway speeds at reduced pressures.

    I'd only use below spec pressures temporarily in order to get unstuck.
     
  10. Easy Rider 2

    Easy Rider 2 Senior Member

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    It is a MYTH that under-inflation will give you better traction.
    In the vast majority of cases it will NOT.
     
  11. GregP507

    GregP507 Senior Member

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    I guess I'm the mythbuster then, because it works well. How much experience do you have with the snow?
     
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  12. Easy Rider 2

    Easy Rider 2 Senior Member

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    Almost as much as you do.

    Most of my 68 years was spent in Illinois, where the winters are about the same as many places in southern Canada; sometimes worse.

    Once again, you don't have to take my word for it. Do a Google search and see what the tire experts and their tests show about tire inflation when there is ice and snow.