my mustang has a 3.9L V6 engine, my question is is that common because everywhere i go the normal V6 engine is 3.8L.

 

Your engine is a 3.8L, The bore and stroke is the same as it has always been. I asked the Ford technicial rep that visits the dealership I work at and His answer was "because they redesigned the intake manifold". I asked him how an intake manifold increases engine displacement and he just laughed and couldnt answer why! So I asked If Ford could design a manifold for the 4.6L to bring i up to 5.0L!!

 

yeah i was bewildered by that, thanks for answering, so that means the 3.9 sticker dont mean a thang and i can use 3.8L parts =)

 

Yeah, It is just another thing Ford has done that we will never understand!!

 

3.9l? what year is your mustang? Must be a new thing i have never heard of it before i know the new 05's are coming out with a 4.0 though

 

its a 2004

 

You sure?

3.9L ford = 3.80"X3.46" bore and stroke
3.8L ford =3.81"X3.39" bore and stroke

they are not the same engine but share the same basic engine family block (Essex block).

heads are the same but bore size is .010" smaller with the 3.9L than the 3.8L

 

Technically the 04's are 3.9's, but there is no performance difference. It's the same engine
Half of the 2004 engines are 3.8 and the other are 3.9. I guess halfway through the production year they switched over to the 3.9. The 3.9 will give you 1 mpg less on highway travel, 26 in auto as opposed to 27 in auto that the 3.8 gives. When you open your hood, look for the white sticker on top of your radiator fan, if it says v-6 then its prob a 3.9 liter, if it says 3.8, then its obviously a 3.8.

 

there is a 3.9 liter mustang made in 2004
it had a bigger crank, bah i forget Ford is a little lazy when it comes to numbers they did make it a 3.9 and it had about 200 hp.

Though 10 hp increase you won't feel anyways :\

The website says 190 but why change it they were dropping the model in half a year so they left it at 190, but it was more powerful than the 3.8

and the 4.0 has 210

 

Strange that the numbers I got from ford state that the 04 3.9 and the 4.2 has the same bore as 3.8l(3.81in) but has a stroke of 3.48in. and 3.74. It still makes 193hp at 5500 and 225 @ 2800. Wich is 15 less torque than offered in the freestar which is where the motor came from. That is probably where people think the new intake is coming from