I have a cracked block on my 2003 Disco 2 with a 4.6. I purchased a 4.0 to replace it and am wondering... can I put the 4.6 crank in the 4.0 block without changing anything else. I am not rebuilding the 4.0 as it has few miles on it and has no issues, but as I have already got the 4.6 crank and new bearings, would it be OK to swap that out and increase the 4.0 to 4.6 or is there a difference in the connecting rods too?

 

Are you having the cylinders honed? If not, l'd be somewhat concerned about cylinder wear. That 4.0's pistons have been going up and down the same distance it's entire life...and when you basically enhance that length of movement...there may be an issue with the bottom portion of the stroke...since the rings/pistons have created a "stop groove" in there downward motion area. You will be going past that groove, now. Which could cause stress on the oil ring and eventually, causing it to fail.

Edit: information about crank sensor difference was wrong (was thinking Gem/Bosch swap...this is a Bosch/Bosch swap you're doing).

Brian.

 

Connecting rods are different lengths in 4.0 vs 4.6.

 

Is there any advantage to using the 4.6 SAI heads? Are the Valves the same size as the 4.0 and will the computer care if the SAI is not there...