I have an 02 Jag XJ8 that needs a new motor. I have studied up on putting a LSx engine in these and have decided to go with a kit from jaguarspecialties.

I was debating on what engine/trans to put in this and was hoping maybe you guys could give some suggestions.

This will be only used on the street of course. Right now I am sticking with NA but a turbo in the future is not out of the question depending on how the car performs.

I am looking to get 400 hp or at least close to it. I believe it was about 300 stock so the 100 hp bump should be great and the reason I don't believe any boost will be necessary.

Also due to how many parts I will need, most likely I will purchase an auction car. So a basic rebuild is most likely. Also I have rebuilt smaller 4 bangers before and large diesel engines but I have no experience rebuilding LS engines.

My first thought was that a six speed auto would work best because of the 3.08 gearing in the rear. So I am looking at getting an LS3/6l80e combo. After looking at the huge price drop and the fact that the original engine weighs 440lbs I was wondering if a iron LS flavor might serve as well. The engine mounts further back than the original so it will shift more weight to the center, so I was thinking that the slightly heavier engine would not be an issue. I do not have any experience with how changing the weight up front by 50 to 100 lbs would impact the steering or suspension.

On that train of thought how easy is it to mate up a 6l80 to a LQ4 or similar iron block.

I would also feel better about buying a used iron block over an aluminum one so that any problem could be bored out.

I do know that the 6l80 has been fit into a few jags without cutting, so I don't see the larger size as being a hangup.

Of course maybe someone here has a completely different recommendation. I would be glad to hear it.