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From 3.7 to 3.9???

1K views 2 replies 3 participants last post by  Lear96 
#1 ·
Will a 3.9 from a 99 replace a 3.7 from an 04? If so, what issues will i encounter?
 
#2 ·
No. This is not a doable swap. The electronics are completely different and you are not gaining much if you went ahead and did this.
Just find a wrecked Dakota or Durango with the 5.2/5.9 from 97-99 with the transmission and wiring harness and do that swap. You will gain power and fuel economy over this swap.
 
#3 ·
^1+. While I fall in the "There's no replacement for displacement." crowd, you're really going to see nothing from swapping in a 3.9. Unfortunately the numbers just aren't there, the 3.9 puts out 175hp and 230 ft-lbs torque, while your 3.7 does ever so slightly better clocking 210hp and 235 torque. However, the 3.9 makes its torque peak at 3,200 vs. the 3.7 screaming at 4,000... but the simple fact is, you won't be happy with the swap and it'll be way more trouble than it's worth. Go find a 4.7/5.2/5.9 if you're after power.

Good luck.
 
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