i thought the v6 was 3.8L and the gt(v8, non supercharged) was 4.6L, ans the cobra(v8 supercharged) was a 4.6L too. the 3.9 must be a stroked 3.8.

 

3.8L= 3.81"X3.40"
3.9L=3.80"X3.46"

 

MD fugger'd up, he meant V6 not GT

 

the premium (isnt that the name of the options) v6's got the mad wicked 3.9 stroker good for about no horsepower.

 

A bigger cubic engine doesn't produce more hp it produces more tq. That's why when you put a stroker kit on your engine, you get like 30-40 more tq and like 5-10 hp. Also, having more cubic inches alos means your engine can suck in more air if it's available, meaning BV heads on a stoke 3.8 would be overkill because you'd slow down the air velocity, but with a 4.2 you can use that extra airflow and produce more hp.

 

hey cobra, where did you get those bore + stroke numbers from?

 

I have a 3.9 in my 04 Stang. It is the same engine out of the ford freestar which is rated at 193hp and 240tq. At my school LTI they have a dyno and wheel horsepower was 171hp and 218tq with no mods. The estimated 1/4 time was 15.8 but I haven't been able to get lower than 16's. I'm not sure how well calibrated the dyno was either.

 

a ford tech paper from a fellow mechanic. i made a copy. i'll see if i can find it and post it up

 

that'd be cool, also if you knew offhand where the torque peaks out(example 220lb-ft@2750 rpm) this whould also be helpful, its probably the same spot but if it would be different it would be nice to know. thanx

 

I don't recall what the rpm the torque and horsepower peaks out at and I was unable to get a printout from the dyno. If I get a chance to run it on the dyno again I'll write down where it peaks at. At fords website it list it as 193hp @ 4500 and 240 @ 3750