Thread: 3.9 to 4.6???

In the absence of others - I believe the 3.9 can be taken to 4.2 with a new crank, but the 4.6 uses a slightly different crank design so you generally can't use a 3.9 crank in it (Although it's the same piston size as the 3.9). The good news is that if you get a hold of a short 4.6 block, you can bolt all your 3.9 goodies to it. ( Small mods only req like a spacer on the nose of the crank etc)

Have a read of this

http://www.v8engines.com/engine-4.htm

3.9 can go to 4.2. Different cranks, rods and pistons, but given the availability of 4.2 parts, that might prove a tad difficult.

4.6 cranks, rods and pistons cannot be used in a 3.9 block.

Ron.

How about 4998CC?

http://www.realsteel.co.uk/section1.pdf

Regards Philip A