This feels like a silly question to ask, but how can you identify if an X351 has a 5.0 or 3.0 (petrol/gas) engine in it? Lots of the cars are debadged in the rear where it indicates the liters, and under the hood they appear visually-identical as far as I can tell.

Never seen another car with two engine options of substantially different size that look the same under the hood.

 

vdpnyc, well, if it is a 2012 or earlier car, it definitely has a 5.0L motor in it. It is more a question of whether it is supercharged or not (this applies to US cars only, european markets this is not the case).

Now for the 2013 and newer cars, it is going to be a safer bet to assume the car has the 3.0L motor, especially if it is the lower trim packages. As you get closer to 2019, the base pretty much only came with the 3.0L engine and only the XJR and limited Portfolio cars had the 5.0L engine. Almost all others got the 3.0L engine. Granted, starting in 2017, there was the diesel option available in the US, but those are a rare kitty and looking under the hood is pretty obvious.

Oh, one other thing, take a look at the front wheels and see if you see a CV shaft. If you see a CV shaft, then it is definitely a 3.0L engine. The XJ was never offered in AWD with the 5.0L engine. During my trip to London, I got to talk with some high Jaguar executives and there was talk of making a 5.0L supercharged AWD car, but the transfer case was too limiting and they would have had to detune the motor to 458 HP. So, sadly, the car never made it into production.

I would need to look at my car and do a close look. My original XJ was a 5.0L motor, but the new one is a 3.0L. I will see if I can spot any other differences.

 

The only relatively easy way I know of, at least for the supercharged version of the V8, is the size/length of the supercharger coolant jackets which sit on top of the engine in plain sight (albeit under the engine cover), and the engine cover itself.
The V8 has a bigger/longer supercharger than the V6 (Eaton TVS R1900 vs R1320) and that extra size is reflected at the rear of the engine where the rear of the SC coolant jackets is longer and sits much closer to the firewall. The engine cover on the V8 is also a little longer at the rear and a slightly different shape.
The V6 replaced the NA V8 in 2012 so I don't think there was ever an X351 model with a choice of the NA V8 and V6 but there may have been a short time in 2012/2013 when both were available.

 

This is a 5.0 SC, if it helps:


Somewhat amusingly, while I was looking for the 5.0SC, a dealer in London tried to sell me a car that had a 3.0 Diesel under the bonnet. He apparently couldn't tell the difference.

 

Ugh, so there was a N/A 5.0 too?? So confusing.

Anyone have images of the exact differences (i.e. longer supercharger) in the S/C 5.0?

I've examined a bunch of engine bay photos from ebay and can't visually see any differentiation, other than the occasional coolant reservoir overflow hose that seems to be routed differently in some cars, albeit potentially incorrectly.

That's sad, the diesel really does look different.

 

Yes, there was. Our first XJ-L, was an early production 2012, and it had the N/A 5.0 engine.

 

The reason it's confusing is the unique thing Jaguar did? The V-6 and V-8 use the same block!! Yes the V-6 has 2 less pistons and those are missing from the back of the engine. So the entire front end of the V-6 and V-8 is literally identical! Great from a manufacturing view point because now there is a massive sharing of parts between the two engines.

Tough for you because as you posted this makes it more difficult to see the differences. But as posted above by OzXFR take off the engine cover and the larger and longer TVS1900 blower is the key.
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My suspicions were aroused when he declined to take a picture of the engine bay for the advert.

 

Chevrolet did something similar, by "shortening" a version of their venerable "small block" V-8, turning it into a V-6. However, Chevy actually removed the unused cylinders from the engine block, making the block visibly shorter and lighter, therefore improving the weight distribution of the cars that the engine was installed in. I wonder why Jaguar didn't take the same opportunity to improve their vehicles/ performance. (lighter engine block, lighter cylinder heads, lighter crankshaft, less front end weight on the car)

 

So there are two empty cylinders at the back of the V6!? That is odd design, albeit understandable from a cost perspective.

Is there a way to tell from the VIN maybe? It is difficult to determine if the info in the VIN decoders are accurate and unique to the car, or some boilerplate content they show for every vehicle of the same model.

 

See here for a brief explanation of the AJ126 design: https://www.caranddriver.com/news/a1...ers-redundant/

 

Yes the VIN will always be the definitive answer. At least as far as how the car was built when it left the factory.

Thanks OzXFR as I have not read such a detailed explanation before so only had a slight knowledge of how they actually did it.
This is a great diagram that makes it easy to understand;



So even better than I thought because the back of the engine and total length are the same so engine/transmission mounts, transmission and starter all attach the same way. Heck even the oil pans are the same!
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In fact by this desing JLR keep x351 chassis weight balance approx same regardig the engine mounted on front. (btw: Gasoline engines are made by Ford, Diesels are joint venture PSA/Ford) Diesel engine have approx same weight than V8. 2 Litre 4 pot gasoline are exeption, its much lighter, mut the lenght are same than V8 so they can have same mounting points in chassis.
x351 are have quite good balance when taken to the limits. It is a big cruiser so for sure its is not a sport car, but still compared its size it is suprisingly good on track. (i made Panamera running out of all it have on local track just some months ago, managed to snip some 0.4 - 0.8sek faster laptimes than he) -> There went my tyres too... Never learn..

 

That's a very good point from Vasara!
I weighed my XJR and found it had an almost perfect 50/50 weigh distribution. Kinda surprising for such a big car!
Here is my Dyno and weighing thread if you want to see some numbers?
2014 XJR Weight
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Interesting article, and a good explanation how jaguar accomplished the task.....however, it still seems to be an "over complicated" solution to the problem, especially with respect to the "split crankshaft" and balance weighting that had to be added to it.....

 

That's fascinating design! So basically, by eye, the only giveaway is to look to the very rear of the engine bay for a 4th coil/wire (on each side) near the firewall.

Checking the vin is probably easier...

 

The crankshaft are straight on V6, where V8 have 2 last pots. Its actually not "same" engine block with just plugged pots, the casting of the block are different, but made so that all the parts fit, exept specific for another. (manifolds, etc..). By this the desing are overall actually much simpler, since there are only one version of chassis, with single mountings (full alumium construction -> this are huge advantage) and auxilary parts for both engines are mostly same.
The V6 was added later and by this they didint need to re-desing the rolling chassis production. Very clever move from Ford / JLR.

clubairth1
Yes indeed. Engine sits quite far back over front axle. On track i only miss steel rear springs, since when setlling x351 for slight 4 wheel slide to the fast corner (DSC Off) the rear autolevelling sometimes stepping in and body change its position in mid corner. (first times it happens cabin are full of hands for a moment and skidmarks on panties)
However: x351 are more road cruiser than a track car. On road the air springs are nice, even they are not tuned as soft as many other vehicles with air suspension.

 

chris the V6 supercharged autobiography sounds very simular but having owned both would say the V8 just edges it on revving it up , ps in the uk your car and mine both the v8 versions of the autobiography , only 18 were made for the UK market BUT only 7 were made of the V6 supercharged version , making it the real UNICORN , mine was a jaguar press car , look it up here it is odessey/metalico red , stupidly sold it with under 20,000 miles to buy the v8 version , but love it

 

The v8 has a more throatier sound to it when revving also apron acceleration .the v6 has a sounding Whine to it , compared to the GROWL of the v8

 

I personally prefer the V8 over the V6. The big thing is the low end torque. Now, I am comparing a N/A V8 to a supercharged V6 and also a 6 speed tranny (with the V8) as compare to the 8 speed with the supercharged V6. The V8, you could just ease into the gas some and around you went. The V6, I just don't get that same feeling and normally to get the "up and around" feeling I was used to, involves the tranny downshifting a gear to get the RPMs up a little bit. But then, this is also the difference between having the car at 1800 RPMs at 60 mph withthe V8 where the V6 is down around 1500. So, take that for what it is worth.

I would love to get my hands on a supercharged V8. But, I have a feeling that the extra power is not going to net a much bigger smile on my face when pushed. There reaches a point where practical acceleration on the road reaches a limit. But then, I would also most likely be upgrading the tune and pulley to push the motor up to around 600 hp, but, that is a different story for a different day.