Engine 3.9 V6 To 3.8 V6 Swap

[Karson Lewis]

I have a 2004 mustang that has a 3.9 ltr v6 that blew a rod I'm attempting to swap in a 3.8 v6 that was casted by the codes on the block in 97. What major things am I gonna have to do to complete the swap such as swapping heads? Buying a fly wheel with a counter balance as the 3.8 has a counter balance on the front pulley and my 04 3.9 does not. Any help is appreciated. Thank you!

 

[wmburns]

IMO this does not seem to me to be the best swap. Have you searched on car-part.com for a motor that matches your car? The replacement V6 does not have to come from a Mustang.

However some of the differences that I can think of:

• no split ports on the intake. EXPECT to have DTC codes from the missing IMRC's
• 2000 and older V6's use an ECT sensor. 2001+ V6's use a CHT sensor. The older heads likely will not be drilled for the CHT sensor.
• For best results use the motor wiring harness of the ORIGINAL car.
• Cam sensor. Ford used several CAM sensors over the years. EXPECT the older motor will use a different cam sensor (2 wire verses 3 wire).
• Different fuel injectors.
• you have already mentioned the internal/external balance "issue".
• The coil packs have different part numbers. I believe that the connector is different.