lordshwa

Hi all,
I'm kicking myself for getting the 3.9L as opposed to the 3.8L for lack of parts. I know some are interchangeable, but I'm not quite so sure on others. K&N has a Fuel Injection Performance Kit which is (as far as I can tell) mostly a cold-air intake which accepts the mass air sensor and provides tubing back to the throttle body. This part is listed in their "Application & Part Search" for the '04 3.8L, and of course they have no listing for the 3.9L at all. It's K&N part #57-2532. Anyway, does anyone have any idea whether it would be a reasonable idea to put this on my 3.9L? As far as I can tell there's no reason why not, but I've been known to be a bit naive with intake issues in the past so any advice would be much appreciated.
-Josh

Dark02Pony

its interchangable its basicially the same exact motor they just rounded the # up from 3.8 to 3.9, almost like the 5.0 is tech. a 4.9 you wont have any problem using 3.8L parts on your 2004 ive checked on a buncha parts for 1 of my friends and its the same part #s for 3.9 as it is for the 3.8 on them all, i have the KN FIPK on my 2002 3.8 its great and an easy install plus you cant beat the 1million mile warrenty!

dfhurleydude182

Yeah, as far as I know all the parts that work on the 3.8's fit and work just the same on the 3.9 L

lordshwa

Thanks guys! One more question then, has anyone actually tested whether this 3.8/3.9 interoperability apply to superchargers made for the 3.8 as well? Please excuse me if the answer is obviously the same as for all other parts. :-)
-josh

Dark02Pony

Yeah 3.8 and 3.9 is same exact motor ford just decided to round it up

future9er24

dang! i never knew that. i always thought it was just a typo when sites sed 3.9L. WOW learn something new every day! :w00t:

Dark02Pony

haha yes indeed! its basicially the same deal with the 5.0 how tech. it was something like a 4.983 but called the 5.0...btw 49ers OWN ( as in ur sig )

lordshwa

EXCELLENT. Many Thanks
-josh

Dark02Pony

very welcome

orange3.9stang

Actually, the 3.8L & 3.9L (& 4.2L) all share the same block (same 3.81" dia. bore), connecting rods, and heads but all three have different strokes.

Ford uses 3 different Cranks and Piston Sets to accomplish this ...
3.8L = 3.390" Stroke
3.9L = 3.464" Stroke
4.2" = 3.740" Stroke

What facinates me is the fact that all three use the same connecting rod as well (6.091" pin to pin).

Luckily for us 3.9L Mustang owners the '03/early '04 3.8L & '04 3.9L also share the same Harmonic Balancer, so the Underdive pulleys do fit. Also, the Catalytic Y-Pipe is the same so any of the aftermarket exhaust kits work as well.

Just wanted to state some facts based on my personal experience !!