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4.0 from 3.8 swap.

Discussion in '2005-2010 V6 Mustang Tech' started by 6w5, Oct 11, 2008.

  1. 6w5

    6w5 Truck2010

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    Yes, I searched and didn't see this brought up or at least it didn't appear to. Not that I would do this but it is more out of curiosity and the fact that a friend of mine put the idea in my head (of what if).

    Now onto the topic, has anyone put a 4.0 SOHC into a 1999-2004 Mustang coupe that originally had the 3.8L engine in it? I think it wouldn't be that hard and don't think that it would have a major snags. I know that the engine puts out like 210 HP and 240 FT LBS of torque compared to our 193 HP and 215 FT LBS of torque. I think it would be a decent step up and I like the idea of the swap, it would be a throw back to the 302 to 351 swap.

    Food for thought I guess. Now all of my friends are waiting to see how long before I get the idea into gear to do it, although I have to say I am happy with what I have.
     
  2. slow_v6_stang

    slow_v6_stang Two Eaton blown Fords

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    you know there are a lot easier ways of gaining 17hp/25ft lbs...
     
  3. atlanticblue98

    atlanticblue98 Bazinga!

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    it would make more sense if you had a singleport
     
  4. Justin251

    Justin251 hotpocketssssss

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    You can't be serious.
     
  5. slow_v6_stang

    slow_v6_stang Two Eaton blown Fords

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    no, even then it wouldnt make much sense
     
  6. taylor0987

    taylor0987 New Member

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    the 4.0 is an entirely different engine from the 3.8 and the car's mounting system is different.

    so you will need to fabricate motor mounts.

    the 94-04 mustang's 4 speed auto trans won't mate to that engine.

    to use the 5 speed auto, you would need to swap in the electronics from either a ranger, explorer, or an 05+ mustang, depending on what type of throttle you get on the 4.0 engine (cable or drive by wire)

    to use a manual transmission, you could probably make the 3.8 computer run it with a tune. you'd have to modify the wiring harness and maybe rig up some sensors to make it all happen. but it should be doable.

    for all the cost and bother, you could instead add ported heads, cam, intakes to a 3.8 or better yet a 4.2 and just drop it into your car.
     
  7. 6w5

    6w5 Truck2010

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    What have I started? lol.

    Yeah, I kind of figured there is more to meets the eye as far as fabing up stuff to make it work and doing a ton of other need fixes to make it work but it would be nothing I don't think couldn't be done and a fairly experienced person could do fairly easy.

    Guys remember this originally was not my idea. Personally I while I think the idea would be cool, now that I have thought about it last night, I don't think that it is worth it either not only because the HP gain typically is not worth it, you could get that gain out of a CAI and exhaust. The thing I think my friend was thinking was more on the fact of it being a "first". (Like the guys that put an M-112 or the guys that put the 4.2 in the 1999-2004 cars).

    Besides I don't think I would do it for two reasons one from what Taylor0987 said and from what I have been looking at this morning on the net and all the fab up and cost alone it would be a costly and uneffective. It would end up being a novelty install ("Look what I have under the hood") - More than a functioning upgrade.
     
  8. Spencer88

    Spencer88 3.8 original member

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    Just drop a v8 in your 99 or get a s197...
     
  9. Avaric3

    Avaric3 Coulda Had a V8

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    for the same gains you could stroke your engine to a 4.2
     
  10. JRicky

    JRicky New Member

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    just make the 3.8 into a 4.2.. more torque than tnat 4.0 will put out
     
  11. Superpede1

    Superpede1 New Member

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    Yup, would probably end up costing you less too.
     
  12. Avaric3

    Avaric3 Coulda Had a V8

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    for a 4.2 out of an f-150 would probly cost you about $500 and for a forged 4.2 rotating assembly it would cost about $1800
     
  13. GhostRider99

    GhostRider99 Seek and DesTory!!!!

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    drop the 4.2, more torque!!! and its proven to be a beast once moding!
     
  14. cobra232

    cobra232 New Member

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    i would think a small bell 4.2 FWD with the 05+ 4.0 trans would be a much better swap if the electronics could be worked out. but then again it probably would not be worth the effort
     
  15. monk36

    monk36 back in black

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    Only reason I could see someone wanting to swap in a 4.0 wouldn't be for 17hp, or whatever, but b/c there are many more good products for the 4.0, but I can't even see that justifying it. A 4.2 would be much more practical.
     
  16. BISKIT

    BISKIT New Member

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    Yes it would. ;)

    We have done a couple of 4r70w swaps (built trans) into GT's and I can tell you that the 5r55s (S197 auto) is shared with the V6.
     
  17. taylor0987

    taylor0987 New Member

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    So you are saying the 4.0 and the 4.6 have the same bellhousing bolt pattern?

    Let me clarify then-- I was responding to the original poster who asked about starting with a *v6* mustang, not a v8.

    The 4r70w transmission for the 3.8 has a different case and bellhousing bolt pattern than the 4r70w transmission for the 4.6.

    In other words, a 4r70w for a 3.8 does NOT bolt up to a 4.6. So no, a 4r70w for a 3.8 will not bolt up to a 4.0 engine.
     
  18. Galeocerdo

    Galeocerdo Cuvier

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    While it isn't the most efficient at adding horse power it is a mod to do to be very unique. I have thought about doing it to my 98 3.8. Kind of like the guys who put a fastback body on an 03 Cobra chassis. It was just a cool idea.
     
  19. BISKIT

    BISKIT New Member

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    Want to bet. ;)
     
  20. taylor0987

    taylor0987 New Member

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    Well I guarantee you that a 4.6 4r70w from a Mustang does not bolt up directly to a 3.8 engine. I'll bet $3000 that it won't.


    You didn't answer my question:
    Does a 4.6 4r70w bolt up to the 4.0? Do the 4.0 and the 4.6 share bellhousing bolt patterns?

    Once you answer that, then yeah maybe I'll take up your bet.