Quote:
Originally Posted by hermanpj
Elemental (Chris?) could you go so far as to get 4.6 out of a 3.9 by putting 4.6 crank, rods and pistons in it? Or is 4.2 the practical limit without changing to a more recent engine block?
Did you change the chip when you went from 3.9 to 4.2?
Assuming one would have to replace engine managment chip or the whole EFI computer to get useful power out of the upgrade - would doing this cause problems w the OBD / multifunction display unit.
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THe 4.0 and 4.6 Crank is too large for the journals. You COULD transplant a 4.6 into a 3.9 block with a bunch fo machining that just wouldnt make sense.
Also, the 4.0 is the same bore as 3.9/4.2, but the 4.6 pistons require a larger hole.
I did change the chip to a 4.2 chip, but when I had the 3.9 prom in it ran just fine.. I changed it to address a cold start issue. You could use the 3.9 prom without any problems or concerns in my experiance.
