You auto guys.

Discussion in '1996 - 2004 SN95 Mustang -General/Talk-' started by LaserSVT, Jul 13, 2008.

  1. I have an auto 98 GT with 3.73's, but I haven't bought a speedcal yet and my speedometer is way off (although I have referenced it with a gps), so I can't measure speed or MPG. What rpm (and speed, if you happen to know it or have a corrected speedo) are you doing in OD to get 25/26 mpg?
  2. You might not have a 2500 RPM Stall TC in it.

    I have 4.30's in my auto car, I see 3000 RPM at 80 MPH.

    Yes, I forgot to mention that you should do the J-Mod.

    When I put a stock Mark VIII/Mustang GT TC in my TBird, I could launch at 2700 RPM with a good tire. Starting in 2nd gear, it was around 2500 RPM.

    I am getting 20 MPG in the city and 26 MPG with my 96 TBird. It has a 4200 RPM Stall TC and 4.30's. It is a DD...

    If I had a Mark VIII, I would do the J-Mod, a 3200 RPM stall TC and 3.73s with a Trak-Lok differential. It would be a fun DD that wouldn't be to bad on fuel.
  3. Its a LSC so I have the trac loc already. If I do gears it will be 3.73s. I drive the speed limit and dont punch it at all going to and from work and can only get 22.5 mpg average :(
    Whats the J mod?
    And Brian I thought the Marks didnt have the IMRC :scratch:
  4. 22.5mpg is horrible mileage for a stock Mark.....I would certainly check into it.

    And yes, the Mark VIII engines had the IMRC plates...just like all early 4V's. They didn't remove them until the '99 model year in the Cobra's. Pic below....


  5. The fuel pump/injectors/lines/filter are all new. The car was running lean and gave the same mileage. I did 450 miles with the cruise set at 75 mph and thats the best I could do at 22.5 :shrug:
    Runs perfect and no leaks so IDK where else to check :shrug:
    It is a 255lph pump, dont know if that matters :scratch:

    As for the J mod, looks like fun.
    Guess ill just do the remap first and see if im happy with the faster shifts and change the shift points :shrug:
  6. Ok Brian, after testing out the mileage thing it seems the car will see 26.2 average doing 70 mph on my drive to work. It drops to 25.1 when on the back roads doing 60 but alot of sweeping turns. :shrug:
    Sound normal?
  7. Pretty close I would say. You did mention the car does have a few mods, does it not? When was the last time it had a tune up (plugs, fuel/air filter, etc), since those would contribute as well. I'm pretty sure my dad averaged 95-100km/h on his trip (knowing the way he drives) where he knocked down the 30mpg, which equates to about 60mph.....which is probably where the majority of the difference in fuel exonomy lies.
  8. get this it will convert your car into awd

    AWD Kit [AWD45] - $450.99 : KaleCoAuto, Hard to find automotive items!
  9. Thanks, but I like RWD :shrug:
    Besides I spent all my money on the O-pipe and two bars of boost :nice:
    I was thinking about the oil bypass kit but will wait till I get my third boost bar.

    And yeah Brian, I can hit 60 on the highway and knock down 28.7 mpg but I am in danger of getting run over :notnice:
    The plugs/coils and whole fuel system are new.
    Im fat and prolly start a little faster than I should which both will contribute to lesser mileage :shrug:
  10. I've had 4.10s for 6 years. I get great mpg, I run 3000rpm at 80mph. I would never dream of having less gear. That would be a mistake with a 4R70W.

    3.73s can suck my balls.:)
  11. What mpg do you get at 3000rpm doing 80mph?
  12. as you wish sir i just figured you would like an awd system but you tore that idea apart but yea oil bypass would be sweet. lol get the adjustable powerband too. and to put it all in maybe a jar of elbow grease:rlaugh: