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3.08 vs.4.30 fuel milage

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    #1

    3.08 vs.4.30 fuel milage

    Well today was the first time I have been on a highway trip with the car since installing the 4.30's. So I thought I would check the milage. I am pleased I got 20mpg from ohio to virginia 190 mile trip. But....

    Facts and figures:

    4.30's / / 3.08's

    fuel economy 20mpg / / fuel economy 24mpg

    avg. speed 60mph / / avg. speed 70mph

    rpm at 60mph 2200 / / rpm at 70mph 1600

    1 5/8'' shorty headers / / stock mustang headers

    2 1/2'' dual exhaust / / 2 1/4'' single exhaust

    There's the breakdown kids. Enjoy.


    '90 LX 5.0 mustang
    Big plans
    Tags: None
    #2
    Interesting report!
    2012 Mazda5 Touring | Finally working on the LTD again!

    Comment

      #3
      Originally posted by 1987cp View Post
      Interesting report!
      +1


      thanks for the post
      sigpic


      - 1990 Ford LTD Crown Victoria P72 - the street boat - 5.0 liter EFI - Ported HO intake/TB, 90 TC shroud/overflow, Aero airbox/zip tube, Cobra camshaft, 19lb injectors, dual exhaust w/ Magnaflows, Cat/Smog & AC delete, 3G alternator, MOOG chassis parts & KYB cop shocks, 215/70r/15s on 95-97 Merc rims

      - 2007 Ford Escape XLT - soccer mom lifted station wagon - 3.0 Duratec, auto, rear converter delete w/ Magnaflow dual exhaust

      - 2008 Mercury Grand Marquis Ultimate Edition - Daily driver - 4.6 2 valve Mod motor, 4R75E, 2.73s. Bone stock

      Comment

        #4
        Originally posted by 1980c10 View Post

        fuel economy 20mpg / / fuel economy 24mpg

        avg. speed 60mph / / avg. speed 70mph

        rpm at 60mph 2200 / / rpm at 70mph 1600

        Would be interesting to see the comparison with equal average speeds
        2000 Grand Marquis LS
        2000 F150 XLT 6 inches of lift.
        1987 Bill Blass Mark VII - Sold
        1985 Mercury Grand Marquis Colony Park- SOLD. to a little old lady
        Mercury Owners Group member
        Save The Whales, Restore an Old Station Wagon!!

        Comment

          #5
          Yeah I wish I could have but 70mph is spinning the motor to high to do it for an extended period of time like 3 hours lol. And with the 3.08's 60 was to low of an rpm and I couldn't keep it in od going through the mountains. It would always downshift into 3rd going up the mountains. But I did take several trips to many different places with the 3.08's and never got better than 24mpg regardless if I went slower than 70mph or not.


          '90 LX 5.0 mustang
          Big plans

          Comment

            #6
            Did you install the gears yourself? I know how critical measurements are on the install. I would be looking at about $450-$500 for parts (install kit, gears, and trak-loc dif) through summit. A reputable professional shop quoted me $1200 for everything. I may have to live with the 3.08 for a while.

            2011 Grand Marquis LS Ultimate Edition
            Dual Exhaust w/ AP XLerator mufflers and 3 1/2" tips, Eibach 1" rear sway bar, Pioneer Head unit and speakers, 17X8 Drag DR-72 wheels

            RIP 1984 2Dr Crown Vic "The Millennium Falcon"
            Carbed 5.0 HO w/nitrous , Performer RPM intake, GT40P heads, E303 cam, FRP Shorties, FRP 9mm plug wires, Off-Road H-pipe, Magnaflow round mufflers, 2000 rpm stall
            NA-15.78@91.21, 80hp shot-14.48@96.21

            Comment

              #7
              Do you have any ideas about your fuel economy around town, and whether or not it improved? Don't need specific numbers, just a yay or nay haha
              sigpic


              - 1990 Ford LTD Crown Victoria P72 - the street boat - 5.0 liter EFI - Ported HO intake/TB, 90 TC shroud/overflow, Aero airbox/zip tube, Cobra camshaft, 19lb injectors, dual exhaust w/ Magnaflows, Cat/Smog & AC delete, 3G alternator, MOOG chassis parts & KYB cop shocks, 215/70r/15s on 95-97 Merc rims

              - 2007 Ford Escape XLT - soccer mom lifted station wagon - 3.0 Duratec, auto, rear converter delete w/ Magnaflow dual exhaust

              - 2008 Mercury Grand Marquis Ultimate Edition - Daily driver - 4.6 2 valve Mod motor, 4R75E, 2.73s. Bone stock

              Comment

                #8
                Yes I installed them myself. It's not technically hard, but lol you need to take lots of measurments and have specific tools. Ford racing gears are also the easiest persay as you don't have to set pinion depth, just measure the thickness of the pinion head and shims on the stock pinion, then use shims and make the pinion head thickness of the new one the same as the stock one. You can't do this with any other gears btw just ford racing.

                I think I got around 18-20 in town with 3.08's and I think around 15-16 now.


                '90 LX 5.0 mustang
                Big plans

                Comment

                  #9
                  I'd be a little surprised if a sustained 2500rpm were to hurt anything, but I suppose the noise could get annoying (and the off-throttle engine braking if you're like me and don't have cruise control).
                  2012 Mazda5 Touring | Finally working on the LTD again!

                  Comment

                    #10
                    I dunno if it will actually hurt anything. Doesn't the aod rear case have lubrication problems at high rpm?. Or am I thinking of another tranny?


                    '90 LX 5.0 mustang
                    Big plans

                    Comment

                      #11
                      I wouldn't know, my engines never see high RPM (WOT shifts at 5k).
                      2012 Mazda5 Touring | Finally working on the LTD again!

                      Comment

                        #12
                        Never mind lol. Its the 4r70w I am thinking of not the AOD
                        http://www.dirtydogperformance.com/t...t/prod_57.html


                        '90 LX 5.0 mustang
                        Big plans

                        Comment

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