I am looking for a new engine to put in my (currently blown-up) 2004 XJR, I found a good one with 53k miles on it from a 2006 for a very reasonable price. I understand there were some updates to the N/A engines, and some minor updates to the Supercharged engines. Are the engine internals so different that I cannot use a later model engine in my 04, or could I install that engine assembly in my car using the 04s external components/engine management?

I am finding a lot of engine assembly ads are for 04-05 and 06-09 with some listing 04-07. When exactly were these engines updated, and are they compatible? I’m finding engine assemblies for 04-05 with significant miles on them to be rather expensive for their given mileage

 

One major difference is that the 2006 XJR has VVT whereas the 2004 does not.

 

I suppose that would entail changing the camshaft/phasers or engine management. At that point I wonder if it would be worth it

 

I dont think engine management would be an option at all since your other modules such as for the tranny would be incompatible.

However what if you "treated" the 2006 engine like a 2004 engine and simply ignored the VVT wiring?

This is pure speculation and I am sure others with more knowledge than me will chime in.

 

 

Makes sense, I’m finding quite a few on eBay, I’m looking for the best price with the lowest mileage. Prices seem to be all over the map with these things. Any suggestions other than eBay I may be able to find one?

 

Go to a car rebuilder, someone who buys auction cars and refurbishes them. There is a network of car parts. Some from wrecks, other insurance totals, and some from chop shops.
A pro can ask about a supercharged 2004 engine and find them all over the US. Local is better, freighting one of these would be expensive.
I know one here. Houston is a hub for this industry. LOT of high end cars roll through. Our x350’s are not high end. But the parts are still valuable.
I also would not trust the mileage listed. Most are pulled already.

 

I had to buy a used one, supposedly had low miles. I bought it from Texas and had it shipped to Tampa, FL for $2.5K total. They said it was tested and ran well. The engine that came in was filthy and you could tell they did a very poor job pulling it out. Crank pulley was sitting on the pallet, it was cracked somehow. Was missing the crank pulley bolt, and the inner threads for the crank pulley bolt on the crank shaft itself were all stripped. It was leaking oil out of the valve covers and timing cover. Wiring harness was all chopped up. The bright side to this disaster is that I was forced to replace all the gaskets and seals and a bunch of other parts on it Maybe ($800 worth) and some parts I cannibalized from the locked up engine, basically refreshing the ebay engine. In the end worked out fine, engine makes good power now.


Point is, be ready to put in a little extra work if you go with a cheap ebay engine. Maybe you'll get lucky though and get one in great shape for a good price. Best wishes

 

Can I ask how your original engine blew?

 

Oil cooler line came off of the heat exchanger in the middle of a hard pull around 130mph. Low oil light came on, I put it in neutral and went to turn it off when it started shaking and shut down on its own. Rod bearings were basically welded to the shaft. Learned a lot, the hard way, from the whole incident and swap process.

 

That’s terrible about your car, I bought mine already blown. It still runs but has 0 compression on 4 cylinders. I was planning on replacing everything I can anyway, gaskets, hoses, etc. but good point on the eBay stuff

 

Yikes. Sorry to hear that.