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engine pre-heat for better mpg?

Discussion in 'Prius c Fuel Economy' started by CAlbertson, Nov 4, 2012.

  1. CAlbertson

    CAlbertson Member

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    Has anyone installed an electric engine block heater? It seems this would improve gas milage on short trips. So much of the energy used in the first 1/2 mile is to heat the engine. So I thought, what if you heated it electrically. The block heater is a standard part used widely in Canada and the northern US. it plugs into an AC outlet.

    No, it is not about saving another 2 cents per day. I'm more curious than cheap. I live in California where a block heater would be pointless, it is warm here year round. But some of your live places where it might work.

    I've heard of peole blocking the grill. Large 18-wheel trucks some times have driver adjustable shutters.

    Aside from keeping the engine warm, there is the concept of "cooling drag". It is an engineering term for the friction of air in the cooling system. The shutters reduce cooing drag by reducing the cooling air velocity. Shutters were common on high performance propeller driven aircraft.
     
    #1 CAlbertson, Nov 4, 2012
  2. rwyckoff

    rwyckoff Phev's Plus Home Solar power1

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    A number of us have tried both over the years in our Gen 2 Prius's. One of the other benifits I was trying for was that quicker warmups could also reduce wear on the engine, extending it's life. But two things made this benefit and the others insignificant. First, the engine already lasts longer than just about anything else in the dual drive trains. And second, the engine block heater does not heat the oil hardly at all. Grill blocking also turns out to be insignificant because first, you can't block the whole grill because of the inverter cooler, and other systems in the engine bay, and then a two thirds block is fairly inecfective because of rapid cooling when air in the fifties whistles through. Now other people in colder climates or very short drives may find something worthwhile, but I havn't.
     
    #2 rwyckoff, Nov 5, 2012
  3. james cook

    james cook Member

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    I just get in and go. I floor the gas to heat it up while i'm driving.

    Last 2 fill ups it's been getting down to 7 degrees F here(last 2 fill ups).

    my mpg is at 42 mpg vs 47 when it was warmer. MPG only drops when it gets below the freezing point of water I've noticed.
     
    #3 james cook, Nov 22, 2012
  4. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    The block heater will raise coolant temperature by about 40~50F degrees, maybe the lower number in winter, and the higher number in summer. Fully warmed up the engine coolant is around 190F. Unless the ambient temperature in your region is 160~170F degrees, there's a benefit. ;)
     
    #4 Mendel Leisk, Nov 22, 2012
  5. Ashley7

    Ashley7 Active Member

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    That seems unnecessary? Does it even work to heat the car faster?
     
    #5 Ashley7, Nov 22, 2012
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    I use at 0°C/32°F and below but I'm sure there's still benefits at 10°C/50°F but you may need it plugged in for a shorter time period.

    My work has the plugs on a 40 min cycle and frankly I have no idea what the schedule is like so I never know how long the heater has been on when I return to the car but I have seen benefits such as the engine shutting off in ECO mode with the climate control off just 1km down the road at -10°C/14°F. That's pretty good for a car that has been cold soaking all night (except for the EBH plugged in).
     
    #6 Tideland Prius, Nov 23, 2012
  7. james cook

    james cook Member

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    Yeah it works, I get better mpg on a cold start driving the C like it's a normal car. I have a block heater but I'm to lazy to get it installed.
     
    #7 james cook, Nov 23, 2012
  8. frugaldriver

    frugaldriver Ceterum censeo Carthaginem delendam esse - Cato

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    I'm starting to notice a pattern on your laziness :p. First its the potentially gas saving grill blocking (3 min install, <$2) and now 20 min block heater install .... hmmmm. Well, I cant say much, I'm pretty lazy getting around to doing things that aren't completely necessary as well. And about the weather, last weeks temps were nice (got up to 63 here one day), too bad winter is once again upon us (23 was the high today, and only to get lower...:cry:). Also by "flooring it", doesn't that offset any gains from quickly trying to heat the engine in the first place?
     
    #8 frugaldriver, Nov 23, 2012
    james cook and RocMills like this.
  9. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Flooring a cold engine, regardless of tanking the mileage, is really rough on it, life shortening.
     
    #9 Mendel Leisk, Nov 23, 2012
  10. Tideland Prius

    Tideland Prius Moderator of the North
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    If it's freezing or below, mine's plugged in. It's also 100% blocked at the bottom and I'm holding 50mpg (indicated... so it's probably like 46mpg calculated) with my 6 mile commute and the heater running in ECO mode at temps between 5°F and 20°F
     
    #10 Tideland Prius, Nov 24, 2012
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