As you all know via my posts on regarding my 1988 H&E XJS convertible, I lumped it with a 1995 LT1 and a 4L60E transmission.
I now have the opportunity to purchase a running 1996 XJ with an AJ16 engine but with a bad body. I drove the car and it runs and drives great.
My question is whether this AJ16 engine will drop into the 88 XJS and if so, what kinds of modifications I will have to do to get it in the car.
My plan:
Pull the engine, trans and complete harness with the ECU and transplant it into the XJS.
Pull the exhaust pipe and adapt it to the XJS exhaust
Pull all of the auxilliary electrical harnesses including all relays etc as complete units.
Before I do this I would like to hear from anyone who has done this in the past so that I can know what I am getting into.
Thanks,

 

I have done this twice.

Certainly wont "drop in" but with some parts from a inline 6 XJS it will be real close. You will need the motor mount bracket set (4 pieces) from an Late I6 XJS. You will also need the transmission plate with the spring setup. All can be home made if you have fab skills but all can be found on eBay at the present time for a price.

I wont recommend this swap unless you are a engine electronics genius. It's very difficult to get one of these OBD2 engines to be happy in a swap with out reprogramming and there is no way to reprogram the AJ16's PCM so you'd need to mimic all the emission equipment perfectly or it will always have drivability problems and be cranky. You'd be better off with a 1995 ECM which has less features so you'd have to get another PCM which is just another expense.

Unlike the LT1 the AJ16 needs a completely independent electric fan setup for engine cooling with relays and separate temperature sensor. The LT1 PCM will run the fans, the AJ16 PCM doesn't.

Compared to the LT1 the AJ16 is uninspiring. They are best suited for a relaxed sedan, the AJ16 R is a different story. I'd do this swap for the R, otherwise I'd stick with the LT1. LT1 can make 330HP with some bolt ons and is an EXTREMLY smooooth engine for a v8 with torque right off idle. The 4HP24 is fragile compared to the (well developed by 1990's) 4L60e

The sedan harness is not a good fit for the XJS. There are many differances in how the harness moves through the body and where connections interface with the chassis. A harness from a late XJS Inline 6 would be better.

You'd be better off just buying a nice late XJS with an inline 6. It will be worth what ever you paid for it and possibly more in the future. That's certainly not the case for an 88 with a home brew I6 swap. As built, the later I6 cars are GREAT, and would have many suspension and chassis updates your 88 will never have.
.
I just finished an AJ16R swap, it was very difficult to get it to run right and I've got 20 years experience doing swaps of all kinds, and it was my 3rd AJ'ish swap.