I'm thinking about swapping to a 4.0 engine instead of a 4.6. Is it worth it? The original engine had 217hp, and the 4.0 has 182hp. Will this make the car slower, or is it about the same weight as the <2002 land rovers?
When I do the swap what needs to be changed other than the ECU? How much more reliable is the 4.0 engine compared to the 4.6? Does it still have head gasket issues?

 

HG issues are the same, the main thing that is better about the 4.0 is they seem to be less prone to cylinder slippage after an overheat. I have had several and I swear I cannot tell the difference in HP, probably because that is all at high rpm and down low the torque is about the same. In addition to the ECU you will need the 4.0 air intake hose and lid unless you keep the 4.6 throttle body (it is bigger on the 4.6).

 

Would you say it is worth the extra work to put in a 4.0 instead of a 4.6.

 

I don’t think the 4.0 is less prone to liner slipping than the 4.6 because of the displacement though. The issue with the D2 4.6’s was that they are all from the last 2 years of production. I’m also on a Range Rover forum and liner slipping doesn’t seem to be an issue on P38 4.6’s. P38 Bosch 4.6’s are all ‘99-‘02. I have a 4.0 in my D2 and 4.6 (GEMS) in my P38. The power difference is quite noticeable.

 

I installed a 4.6 from a 2000 P38 with 111k miles in my D2 this spring. No knocking, ticking or oil consumption.

 

I don't think it is worth the extra expense, they are the same work but the 4.6's command a higher price.

 

I am a little confused. Are you reccomending I get a 4.0, or a 4.6 as a replacement?
I found a 4.6 engine that says it fits 1999-2002 Discovery's. Would that be similar in reliability to a 4.0 than a 4.6 from 03-04?

 

I’m saying use a 4.6 unless it came out of an ’03 or ‘04. Extinct is suggesting to use a 4.0

 

For the same or close money I would get the 4.6, I would not spend dramatically more for the 4.6.

 

If you buy a used engine it’s very wise to just do a head gasket anyway while it’s out of the vehicle. At this time put in your existing heads if they are good