4.6 P38 engine into manual 3.9 Disco1

[aussearcher]

Hello everyone,
I'm new to AULRO so apologies if there is an existing thread on this subject - I've looked but not found. The engine in my 98 D1 V8 is a little tired. I have been offered a 4.6 out of a P38 at a reasonable price. I would imagine this swap has been done before - can anyone tell me what is involved? Is it easier to swap in the P38 engine and box as a unit or will the 4.6 mate up to the Disco manual box? Can the 3.9 ECU handle the 4.6? Or should I just rebuild the 3.9 and whack a supercharger on it, or swap in a GM LS engine?
Many thanks
Aussearcher

[bee utey]

The engine will fit fine, however you will have to use all the external 3.9 engine parts (manifolds, timing cover, injection etc) plus a 3.9 camshaft so that you can have a distributor drive. You will also need a spacer on the crankshaft front end as the P38 one is a bit longer. Also a locating hole needs to be drilled in your flywheel as the P38 has a dowel to align its flywheel to the crank sensor. Some dowels and bolt holes in the front of the engine are different too but are reasonably easy to change.

It will perform fine so long as you don't want 100% top end performance. The torque improvement is what it is all about.

[aussearcher]

Thanks - have you done this conversion yourself or know someone who has - it would be useful to chat through the issues.
A

[bee utey]

I fitted a fully reconditioned 4.6 short motor to a customer's 3.9 RRC about 8 months ago so it's still in my memory banks. The only thing I didn't do was fit the cam, the shop did that. You have to decide on your 3.9 camshaft choice, it would be possible to reuse the old 3.9 cam but it's a golden opportunity to put a quality new cam in. Then all you need is normal mechanic skills and some drilling/tapping.

The month before I fitted a second hand 3.9, thread with pics here might help a bit with the remove and refit:

http://www.aulro.com/afvb/technical-chatter/141567-fitting-92-3-9-rrc-motor-into-94-a.html