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Difference between 3.8L and 3.9L

Discussion in '1994-2004 V6 Mustang Tech' started by RedPearl04, Oct 2, 2007.

  1. RedPearl04

    RedPearl04 Can't Touch This

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    I just recently purchased my first Mustang, its a 2004 3.9L. I was wondering if anyone had any information on this engine, and how is it different from the 3.8L? In ways such as performance, fuel economy, modification, and any other information. Thanks for any help.
     
  2. Jester4Kicks

    Jester4Kicks pwn-hawk

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    No difference. Really just a math thing.

    Do some searching.
     
  3. cgrant26

    cgrant26 Chiroptera Parvulus

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    By my calculations, 0.1 L. :p
     
  4. Jester4Kicks

    Jester4Kicks pwn-hawk

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    Even that is overstating it. Ford basically worked it so that they could round up to 3.9 instead of rounding down to 3.8.
     
  5. Vee6

    Vee6 Well-Known Member

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    So you think it was a marketing ploy by Ford to sell more "super-fied" V6's to further finance the V8 GT productions? :rolleyes:
     
  6. cobra232

    cobra232 New Member

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    bore and stroke are different

    3.8= 3.81x3.39
    3.9= 3.80x3.46
     
  7. Jester4Kicks

    Jester4Kicks pwn-hawk

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    Ugh... now I gotta do the math to show where they rounded up.
     
  8. Marc@UPR

    [email protected] Four-Six Mafia

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  9. Raymond

    Raymond `

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    Just forget the math, since no one wants to give you information and only tells you to "search," I'll attempt to clear it up a little.

    There's no difference in the performance, power ratings, or fuel economy between '99-'03 3.8Ls and '04 3.9Ls. Ford got cheap towards the end of production and moved the Mustang engine production to the same plant as the Windstar minivan plant. This is what I have heard as rumor, and what numerous people have told me, so I assume it's true. Supposedly Ford changed a few things in the Mustangs engine to Windstar-specifications, bumping the engine liter up by a little less than .1 liter. When they did the math, they rounded up to 3.9L. Hell, even our 3.8L sixes are 3.75234934 or something like that, rounded up to 3.8. As far as modification goes, ANY part that you see available for 99-04 V6s will work for your car. If the site only says 99-03, then they just haven't updated it yet. If they tell you it wont work, they are stupid and don't know what they're talking about. Welcome to the site though, and have fun modding. :)
     
  10. RedPearl04

    RedPearl04 Can't Touch This

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  11. Raymond

    Raymond `

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    No problem. Nice list of planned mods you got there. You should really consider a set of lowering springs too. linky :D
     
  12. RedPearl04

    RedPearl04 Can't Touch This

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    Thanks man, Im glad to see someone thinks my plan looks decent. I'll definetly look into lowering springs aswell.
     
  13. Raymond

    Raymond `

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    Good to hear. And for the record, while you're doing the 4.10 install, you might want to invest in a T-lock or Detroit Locker so both rear tires will spin instead of one. :)

    And just to help you out a little, an aftermarket throttle body does next to nothing on our V6s. I'd scratch it off the list, as it has even been reported to make us lose powers on relatively stock cars.
     
  14. RedPearl04

    RedPearl04 Can't Touch This

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    Ya, I've heard that, Ive just been lookin at some of the packages at http://www.rpmoutlet.com/newv6m.htm and was gonna get the DynoTuned HiFLO air kit, and it comes with a BBK CAI, 65mm TB and spacer I think.
     
  15. Raymond

    Raymond `

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    I really wouldn't trust RPM Outlet. Numerous members here have complained about paying them and not getting the parts, not to mention the fact that they exaggerate the hp and tq claims that their "packages" deliver. I'd shop elsewhere man.

    www.americanmuscle.com
    www.volpaz.com
    www.uprproducts.com
    www.stangmods.com
    www.maximummotorsports.com
    www.steeda.com
    www.vmptuning.com

    etc etc, check out all of our site sponsors at the bottom of the forums list.

    Those are the sites I tend to stick to. Good luck man.
     
  16. Jester4Kicks

    Jester4Kicks pwn-hawk

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    :thumbup: :thumbup:

    Larger TB, useless.
    TB spacer, useless.

    RPMoutlet, useless.

    Find a better company to do business with.
     
  17. stevos238stang

    stevos238stang stev-o

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    The only difference is the stroke on the 3.9 is slighly longer, why ford did it I don't know, but any mod for a 3.8 will work
     
  18. tjames

    tjames Project Car/DD 238 FTW!

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    3HP difference and its not noticable at all. and to the guy who said it was a marketing ploy.. are you serious??????? you think by selling it as .1L more its going to sell any more cars? no
     
  19. cobra232

    cobra232 New Member

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    pistons will not work from a 3.8 to a 3.9. they are different in diameter and pin location.
     
  20. stevos238stang

    stevos238stang stev-o

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    Hey cobra232 did you have to relocate your ABS (if you have it) when installing your procharger, and can you or anybody tell me about the M90 install.