I’m a 17 year old from Texas with a 2007 XJ8 and I’ve been wondering if anyone on these forums would have any idea or clue as to how and if even possible to turbocharge an XJ8 with the original 4.2L V8 motor. I’ve already looked into supercharging it and that’s basically out of the question. Any thoughts or ideas??? Please let me know

 

Edit :

You need this section.

https://www.jaguarforums.com/forum/x...-x350-x358-28/

 

Anything is possible given enough money. It used to be relatively simple in the pre-OBD days to add devices that increased fuel pressure and retarded ignition timing in reference to the manifold pressure. Or there were "piggyback" electronics developed for some cars that intercepted and modified the injector pulse width and timing, also based on manifold pressure. Another method was to drill the manifold and add an auxiliary fuel injector or injectors driven by an auxiliary computer. But by 2007 I suspect the electronic engine management had become very sophisticated and it would be pretty hard to "fool" the modern computer with any of those methods. It would likely know that what was going in was not within expected range based on what was coming out.

Also, factory turbos used to run very low static compression, like 8:1 and relied heavily on the boost. If you are already running a 10.5:1 static and add boost, you really need fine control over the fuel mixture and timing to prevent detonation and pre-ignition, much finer control than you can get with those old fashioned methods that circumvent the stock computer. Today the way to do it would be with aftermarket programmable engine management systems that replace the stock computer altogether. However, the stock computer is so integrated with the rest of the cars systems that it would be extremely difficult to integrate a different computer, probably not impossible but it wouldn't be cheap. It just isn't practical to attempt such modifications because as cheap as used Jaguar sedans are, it would be far less expensive to just sell the XJ8 and buy an XJR.

When I was your age, if a young man was driving a four-door sedan, it meant only one thing; his parents got a new car and he got the hand-me-down. If that's your situation, maybe just be grateful your parents didn't drive a Chevy Lumina. At least the four-door no longer carries the same stigma as yesteryear and as sedans go, the XJ8 is reasonably quick and about as cool as you can get (we're biased here of course). It may not be as fast as your classmates Mustang, but when it comes time for a group of friends to go out to a concert or ballgame, YOU'RE the one they're gonna ask to drive cause nobody wants to sit with their chin on their knees in the back of a Mustang.

 

There are a few main points that you need to consider before going ahead with turbocharging:
1. You would have to replace the pistons with pistons from an X350 XJR (to lower the compression from 11:1 to 9:1). Just adding turbochargers to the 11:1 compression engine won't work.
2. You would have to install the oil filter housing and oil cooler from an X350 XJR
3. Turbocharged engines normally have oil squirters spraying oil to the undersides of the pistons for cooling. If the NA engine does not have them, adding the squirters could be difficult.
4. You would need to find space for the turbochargers.

 

I'm 99% sure the NA does not have the oil squirters.

Overall, not even vaguely viable to add a turbo.

 

For low boost pressures you wont need squirters or pistons etc. Your biggest hurdle is going to be getting the engine, transmission and body to talk to one another and fuel the engine correctly.

The rest of the physical stuff is as per any other car and not a huge issue (within limits)

Jaguars arent special, they're just cars.

It's certainly possible to have a turbocharged XK8, but whether its a sensible route, or something you're capable of doing is a separate issue. Do a LOT of reading first.

 

Have deep pockets and don't be shocked if you destroy an engine or two.