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Thread: Question on changing gears

  1. #1
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    Question on changing gears

    I've finally acquainted myself with manuals, but I have a question or two.
    In movies and video games, it's portrayed that the best time to shift is right at the end of the tacho, the 'redline' is it? When the engine is revving very hard. But this isn't the case for road driving is it, why?
    Is it that it's a waste of fuel and isn't necessary? Are basic family transport sort cars able to withstand that kind of abuse? Is it just adding extra wear to the engine?
    All about the t-tops

  2. #2
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    If you're looking to squeeze out the best performance/acceleration out of your engine then yes, you want to be changing gear somewhere just below the redline. However, for everyday driving it's a pretty silly thing to do. For getting the best mileage out of the car in terms of fuel consumption and longevity of the engine/gearbox, you want to be shifting nice and smoothly somewhere in the low-to-mid rev range of the engine.

    The occasional run up the rev range for shits and giggles won't do too much damage, as the red line in a road car will most likely be set fairly low for safety's sake, but it's probably not a good idea to be doing it too regularly. Race engines are designed to run to the rev limit all the time, but even they don't last too long when doing it. You'll probably seriously reduce the lifespan of your engine by revving it hard all the time.
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  3. #3
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    In some cars (mostly turbocharged and diesels) there's not much point in insisting after a certain revs if you want max performance since the power delivery decreases sharply.
    Lack of charisma can be fatal.
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  4. #4
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    If acceleration is better after gear change than before it, then you should change under redline (in case of performance driving). The proper rpm might be different with each gear in a car. As said above, in family cars they change earlier for consumption, longevity, and noise.

  5. #5
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    now, im going to play counterpoint here. yes you do lose fuel consumption and incresase wear on your engine if you bounce it off the rev limiter regularly (as i do) but your engine does like to be flogged on occasion. if you pamper it and keep it on the lower half of the tach for its entire life, it wont really run right. a quick jaunt up to redline a few times a week will keep the engine a bit cleaner, and also keep it running smoother.

    i know specifically that the Minis that were kept at low rpms for their lives have more trouble with their superchargers, and with overall engine fuel management than the ones that are more violently driven. this has led to them being in the shop far more frequently and lower overall mpg.
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  6. #6
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    With the Mazda Renesis engine if you do NOT drive it enthusiastically then it can have problems later in life. You are instructed in the Mazda manual to rev it to the rev warning beep, which is about 500rpm before the rev limiter kicks in. Perhaps not as often as we tend to do it -- which is almost every gear change that way the car comes alive.
    "A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'

  7. #7
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    Shifting at red line all the time is basically like driving full throttle all the time on an automatic... it's just silly to do so. It also puts a bigger strain on the engine.
    Previously know as "Rotary.freak"

  8. #8
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    I shift around 3 grand in my everyday driving (Redline is 6 grand) and I get good mileage and my car isn't dead yet. When I merge onto the highway I usually push it higher.

  9. #9
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    Quote Originally Posted by Matra et Alpine View Post
    With the Mazda Renesis engine if you do NOT drive it enthusiastically then it can have problems later in life. You are instructed in the Mazda manual to rev it to the rev warning beep, which is about 500rpm before the rev limiter kicks in. Perhaps not as often as we tend to do it -- which is almost every gear change that way the car comes alive.
    all rotaries are like that. the higher the pressures in the chamber, the longer the apex seals will last. thats one reason my 12A is in good shape. it wasnt driven much, but when it was it gut a good bit of stick.
    Honor. Courage. Commitment. Etcetera.

  10. #10
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    True, but the reason for the Renesis is two-fold.
    First the ECU injects more oil the harder the engine is pushed.
    If it's never revved then it can actually have oil problems.
    Secondly, the 230hp engine has an additional intake control that only opens at higher revs. Again, if it's not kept "working" it can become sticky.
    "A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'

  11. #11
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    I see I see.
    I'm buying a $2500 car with more than 250,000km. Should I resist hitting the redline? Putting strain on a 20 year old Nissan Pulsar sounds like a recipe for expensive repairs.
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  12. #12
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    ah, older cars are governed by different rules
    "A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'

  13. #13
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    Of course. Maybe harsh driving is out of the question then. Thanks. :P
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  14. #14
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    yep ..... I don't rev the Matra's beyond 4500-5000 and the A610 used to be revved out to the red line --- but of course has now blown up twice So it'll be getting treated a wee bit better ( well for the first 2 weeks at least )
    "A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'

  15. #15
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    Lol. Blown up twice. Okay, that's something I don't really want.
    All about the t-tops

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