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Thread: 80+ mph for cruising in a 5MT

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    80+ mph for cruising in a 5MT

    Texas highways are 70-75mph so usually i find myself doing 80-85mph when the traffic at 5-6am just won't let me drive slow without a bunch of angry drivers lining up and flicking me off as they pass me by.

    It runs about 4k-4,200 rpm at these speeds. Is gas mileage the only thing that suffers at this speed? Or will prolonged driving at 80+mph cause the engine to lock up? (I had a motorcycle motor lock up on me driving highway speeds but it was a high mileage used 250cc that had been sitting for awhile so not the best condition)

    It really doesn't feel like the engine is struggling at this speed but i'm wary about keeping her there for too long. It doesn't get near the redline and i'm definitely not hitting 90+.



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    Moderator inuvik's Avatar
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    Quote Originally Posted by jscv0341 View Post
    Texas highways are 70-75mph so usually i find myself doing 80-85mph when the traffic at 5-6am just won't let me drive slow without a bunch of angry drivers lining up and flicking me off as they pass me by.

    It runs about 4k-4,200 rpm at these speeds. Is gas mileage the only thing that suffers at this speed? Or will prolonged driving at 80+mph cause the engine to lock up? (I had a motorcycle motor lock up on me driving highway speeds but it was a high mileage used 250cc that had been sitting for awhile so not the best condition)

    It really doesn't feel like the engine is struggling at this speed but i'm wary about keeping her there for too long. It doesn't get near the redline and i'm definitely not hitting 90+.
    Torque peak is at 4000 rpm so I don't think that's an issue. Now on the other hand is running those type of rpm's for extended period of times with 0w20 oil optimal? I really don't know.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 40.5 mpg (US) ... 17.2 km/L ... 5.8 L/100 km ... 48.6 mpg (Imp)


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    Senior Member Ares's Avatar
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    Opinion:
    Engines life depends in a lot of variables. Engine speed is only one variable.

    IIRC one of our members here drove lots of highway miles. However, I dont recall him hauling ass doing 80-85mph.

    4krpm for an hour or two a day is, IMO, within the "acceptable use." You may want to think of doing maintenance sooner just for protection.

    Now if you're hauling ass 3-5 or more hrs a day, that may be an issue. I'd get an oil and tranny cooler - maybe find some cooling upgrades as far as radiator/coolant is concerned.

    Just keep up with maintenance and you should be good.

    I feel like if I can get 200k miles from a $13k car, it was worth it.

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    Senior Member Cobrajet's Avatar
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    Quote Originally Posted by Ares View Post
    Opinion:
    Engines life depends in a lot of variables. Engine speed is only one variable.

    IIRC one of our members here drove lots of highway miles. However, I dont recall him hauling ass doing 80-85mph.

    4krpm for an hour or two a day is, IMO, within the "acceptable use." You may want to think of doing maintenance sooner just for protection.

    Now if you're hauling ass 3-5 or more hrs a day, that may be an issue. I'd get an oil and tranny cooler - maybe find some cooling upgrades as far as radiator/coolant is concerned.

    Just keep up with maintenance and you should be good.

    I feel like if I can get 200k miles from a $13k car, it was worth it.
    /\ This! I don't think you will hurt anything. But do keep in mind that extended 80 mph freeway runs really aren't what this car was designed for, not only in terms of engine and transmission but also brakes, tires, and handling.

    The Mirage is a city car, and that is where it excels.

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    Moderator Eggman's Avatar
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    Talk to Rkt Ship. I'm pretty sure he does a fair amount of highway travel, though I don't think he sustains 80-85mph.

    He replaced his engine due to head gasket failure.

    I suspect this should become a point of inspection - but how? Note cylinder compression at oil changes? What other measurements can track head gasket failure?

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.5 mpg (Imp)


  7. #6
    Our one car does 70mph for most of the day. It has a cvt so not revving as high as a 5spd but its getting close to 200000 miles and the engine is still fine.

    Eggman: These testers work https://www.amazon.ca/Lisle-75500-Co.../dp/B0007ZDRUI if you have compression leaking into the coolant passage.

    Amazon US: Lisle 75500 Combustion Leak Detector

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)


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    Your countrys are used to high cc engines, here in Europe only high price cars have higher cc engines. So many cars here are 1.2 engines, or less so people use this cars not only for city driving but also long trips. Its usual to see cars like these doing lots of highway at those speeds and for long periods. I had a Smart forfour 1.1 with mitsubishi engine (173000km) and swapped it for my Mirage. As long as you keep your maintenance ok you have no problems. I see everyday bigger engines even diesel breaking up so...



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