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GM 6.2L MPG

Discussion in '1982-Present GM Diesel' started by JHG, Jul 28, 2002.

  1. JHG

    JHG 1/2 ton status

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    I have a 81 Blazer K5, 38" tyres, 4.88 rear, 12bolt/dana44, NP208, 350ci and TH350.

    I was considering swapping the 350/350 out for 6.2/TH700.

    Is it possible to predict what kind of MPG I would get?

    Shouldn´t it be much better than with my current combo?

    I love the 350 but the prize of gas is around $4 for the gallon over here .

    It is would also be good not to have to travel with as much extra gas when I am traveling out of nowhere (my 30 gallon tank is not big enough).

    Jon H.
     
  2. rugger03

    rugger03 1/2 ton status

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    I would visit the following links to see how i got this answer, i dont think its very scientific but here it goes.
    By getting the aproximate milage for the engine rpm from the diesel page link.
    http://www.thedieselpage.com/mileage.htm

    and getting your engine rpm with the tires and gears you have and using the rpm caluculator here
    http://www.4lo.com/

    you would be turning 1963 rpms at 65 Mph which should put you in the 17 mpg area. Keep in mind the milage estimates on the diesel page are for the 6.5 turbo diesel which does have more power, but is less fuel efficant. also the rolling resistance caused by your tires will probally decrease you fuel economy. But you will get far better gas milage than you are now.
    rugger
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Welcome to CK5!!!! /forums/images/icons/smile.gif

    It might be worth it for you to spend a couple of hours and read through the relevant posts on this forum. This topic has been discussed a few times already. I'm sure you'll learn a lot about 6.2s as well, which may help you decide if a diesel is for you.
     
  4. Tybee

    Tybee 1/2 ton status

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    $4 /forums/images/icons/shocked.gif a gallon, Id buy a car.
     
  5. JHG

    JHG 1/2 ton status

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    Thanks for your answears /forums/images/icons/smile.gif

    Jon H.

    P.s. I also have two cars, 86 T/A /forums/images/icons/cool.gif and a little economy box from Suzuki /forums/images/icons/blush.gif
     
  6. René

    René 1/2 ton status

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    That is here the same. The gallon premium fuel costs more than $4 and diesels $3,7. Therefore I double the value of my car, if I refuel fully. /forums/images/icons/grin.gif
     
  7. JHG

    JHG 1/2 ton status

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    I was talking to a friend and he stated that trucks, similar to mine (38" tyres, gearings etc) with 6.2 would not get better than 12 mpg (perhaps that is with TH400?).

    I currently get around 10 mpg (if I dont speed) but it can get as bad as 7 mpg /forums/images/icons/frown.gif

    I am sure you know better than this friend of mine (I surely hope so).

    Jon H.
     
  8. René

    René 1/2 ton status

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    I calculated the gear ratio and came to the conclusion that it isnt really ideal. The 3. speed is somewhat too short and the overdrive cant out-play its advantage. Lock manually the OD and measures. If it doesnt rise around 10%, the end ratio is wrongly selected.

    Altogether however your consumption is too high. Could it be that the engine has a defect or is wrongly adjusted?

    Forget the TH400. Its more durable, but the first speed is 19% longer and it is missing the OD. both reasons, which dont make your car more economical.
     
  9. kickinasphalt383

    kickinasphalt383 1/2 ton status

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    i get around 14 mpg, with my K30 with 36's, 4.56's, and with a SM465 manual (i got the same kind of mileage when i had the TH400 in it too).

    I personally have never seen worse than about 11 (maybe 10) and that was when i was fourwheeling ALL day at the sand dunes. so maybe there might be something wrong with your engine
     
  10. JHG

    JHG 1/2 ton status

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    My get around 10 mpg with my 350/TH350 combo. I use my truck mostly over the winter.

    I think that GM 6.2 with TH700 must get must get MUCH better mpg than that!

    My 350 sbc runs very strong (knock on wood /forums/images/icons/wink.gif ), I think the rear diff (4.88) and no overdrive plays a big role in my 10 mpg. I use 4.88 because I changed my truck for 44" tires, currently I have 38" Dick Cepec.

    Jon H.
     

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