Good morning,

this is my first post on this forum.
I have a Jag XJ8 with the 4.0 naturally aspirated V8 and am looking at converting it to 4.0 supercharged.
what is required for the conversion, is it as simple changing the supercharger and inlet on my AJ26 or would I have to do a complete swap to the AJ26s?

Many thanks

SC

 

Easiest way......


Sell your car, buy an XJR!


The supercharged cars are more than just a blower bolted onto the engine.
Compression ratio is different, gearbox is different, fuel tank is different it has two pumps, ECUs are different, suspension is different etc etc.


Having said that, anything can be done, but......you are at least going to have to purchase a rusty/ written off XJR for all the parts you need.

 

+1 sell & buy

 

Hi there, 7 year old forum post,

I'm very interested in the real differences. Yes, the supercharged version has 50+ other parts mainly for the intake, but how about the lower block itself?

Background: I bought an XJR with an engine that exploded (broken chain guides, bent valves, you know the drill). I have good N/A 4.0 pistons lying around, even the bare block, if my cylinder walls are really bad.

In addition to the rings, for example, is the connecting rod shorter? Is the diameter of the cylinder larger/smaller? Is the crankshaft the same? Bearings, tolerances?
This is just a question if anyone knows. I will have to measure them anyway, but unfortunately I won't have time to remove the cylinder head until next week and I'm VERY curious.

P.S. The chain of the left bank broke and SOMEHOW it still RAN on the right bank (video proof!), which I find really incredible. It sounds like a tractor, but still.

 

Jagrepair xj8 technical guide
Page 24

 

Sadly, I am unable to open that link.My browser says ERR_CONNECTION_TIMED_OUT. Both, http and https.

Update: seems to be related to my country, nice. Fantastic how we block content from other countries

 

NA pistons will not work in a SC engine, they are much higher compression. Bore/stroke are the same.

 

Concerning the XJR, until you have the cylinder heads off that engine don’t dismiss it yet because it has bent valves and broken chain guides. If you don’t know what it looks like inside the combustion chamber, it might be worthwhile to borescope it vs pulling the head. Unless the piston(s) has serious carnage, you still may have a useable bottom end. How many miles/kilometers does it have? Whatever you decide on, make sure to have a reputable machine shop do a complete valve job including the valve adjustment.

 

Pistons - Different (Piston Rings are same)
Connecting Rods - Same
Cylinder Bore - Same
Crankshaft - Same
Crankshaft Bearings - Same

You can verify the above and see other differences in the attached engine parts catalogue.

 

Here's the Technical Guide (if you could not download).

 

Chances are that your short block is still in good enough shape to use again.
The borescope idea from A2B is a good one,

 

Thank you, M. Stojanovic!

Those documents are very interesting and actually answer all my questions regarding the differences.
There are even photos of what the pistons look like.

Had some time today to remove the timing cover. Unfortunately, there is literally a hole in the oil pump (I'm guessing the flying and now very broken chain and guides caused this "at idle"). Only the top guides were still intact (on the cylinder heads).

The car has 140,00 miles and I don't think the previous owner ever heard of maintenance. Everything in the engine is almost pitch black from caked-on oil residue. I've never seen it this bad.
I think I'll give up on this block, but first I'll take it completely apart.

I'm going way too far off topic, so thanks for the information and documents everyone. Good evening!