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Old 07-17-2005, 01:59 PM   #1
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3.8 vs 3.9

i have a 2003 3.8 and my wife has a 2004 3.9 why did ford change the motor size

also it seems to be slower than my 3.8 what gives

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Old 07-17-2005, 02:07 PM   #2
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There has been much much discussion on this issue. In the end, there really is no difference power-wise in the 3.8 and the 3.9. Basically, ford used a few parts from the phased out windstar line on the 04 and it bumped the engine up just enough to be considered a 3.9. It moved the displacement from like 3.83 to 3.85 so they call it a 3.9. As far as power difference, there really shouldn't be any difference between the cars. Do both cars have the same options, tranny, etc?

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Old 07-17-2005, 02:28 PM   #3
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there is no difference in performance or really anything.
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Old 07-17-2005, 06:29 PM   #4
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Depends on the weight of the car, a vert would be slower than a coupe.

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Originally Posted by slvr2000stang
Holy crap he's right.
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Old 07-17-2005, 06:57 PM   #5
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oooh oooh oooh, here's my already-done response for this question since it has been asked eleventy billion times:

Originally Posted by 04stang
as far as them being EXACTLY THE SAME, thats correct and incorrect.

thats realistically correct b/c all parts for a 3.8 will fit a 3.9 and there is none or very very little differences in hp/tq, and the engines look the EXACT same. the only difference is on top the fan, it would say '3.8' whereas on a 3.9 is says 'V6'. also on side of the engine, it says '3.9L RWD V6'

its technically incorrect b/c there are a couple internal differences between the two. the crankshaft is a little offset and the bore/stroke is a little different, thus giving it enough displacement for ford to round up to a 3.9, its something like 3.87xxxx for the 3.9 vs 3.81xxxx for the 3.8L. ford switched this over in mid-04 production, due to extra parts left over from the windstar that was introduced with "the new V6" which is why some 04s have a 3.8 while others have a 3.9.
if it has any extra power at all, its maybe like 1hp/1tq

if you both have coups or verts, as well as trannies. also, make sure you get the same launches. racing from like a 5-10mph roll would be best b/c it just involves flooring it. but race them and see if there is any diff, but make sure the cars are the same as far as weight goes. that will show you how much difference there is. there wont be much, if any.
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