I have an XJ L. What’s the difference, other than performance, with the R?
is it just a pulley and a tune? Thanks for the info. I’m completely new to the platform so I have no clue.

 

Russell, The R versions do have a little more power to them from the factory normally (510 up to 575 depending on year and other options). The other big thing is that the R normally gets some sort of restricted access to more options for the interior and/or stitching. But, after that, not much that I can think of.

 

I guess I should have worded that better. I'm looking more for what the performance difference is. Was it a completely different engine?
Did they come with just different modifications and programming to get the extra HP?

 

Not an expert on the XJ, but judging by your handle and location you have a US XJL supercharged.
I *think* the XJL supercharged was rated at 495 PS while the XJR was rated at 510 PS (same as the XFR and XKR).
The difference is purely the ECU tune (in JLR speak the PCM - Power Control Module - tune), no change to either the SC (top) or crank (lower) pulley.
Exactly the same AJ133 SC engine with zero differences other than the tune.
You can tune an XJL SC to 630 PS with a larger crank pulley and tune from VAP for not a lot of $.

 

what does the PS stand for? And, yes, I have an American version. I’d also be interested to know where I can find more info on this VAP you’re talking about.

 

https://www.velocityap.com/

 

PS = pferdestärke.
A German term for horsepower, see here: https://www.carthrottle.com/post/wha...-hp-kw-and-ps/
For example 510 PS = 503 bhp.
VAP = Velocity AP, a Canadian based company which offers pulleys and tunes for the AJ133SC (and other engines), follow Stuart's link.
Not real cheap but considering the low volume and the amount of R&D involved and their sterling after-sales service good bang for your buck IMHO.

 

After a quick google search last night, i found Velocity on the good ol web. I'm going to be in touch with them about some particular questions I have but I think that's the route I'll be going. Thank you for the responses.

 

I'm not familiar with ECUs. Are these fairly safe for the car? Meaning will it cause issues with anything or void the warranty?

I have a 16 XJL V6 and was surprised to see a pretty significant jump in horse power Velocity listed.

 

Of course it voids the warranty.

 

The XJR is more than just the engine tune? No hood vents unless it's an R and there are suspension and calibration changes as well as Forged 20" staggered rims.
This is a big upgrade as many people have bent rims. I had 3 bent rims on my old 2005 S Type R.
But with my 2014 XJR so far nothing at 42K miles. And as everyone knows the roads don't seem to be very good anywhere!

Tunes appear to be safe. I have run my stage II tune for a year plus with no problems and have had the car inspected and passed by the state as well. Run my car to 180 mph multiple times.
The power just keeps building. The most amazing part for me is the noticeable increase in gas mileage which I was totally not expecting!

Any tune IS detectable by the dealer or anyone looking for it. I have posted this info before because even some aftermarket scanners can indicate changed PCM software.
I also never flashed back to stock when going to the dealer for warranty work. Of course my car has been almost perfect since I got it and has only had a single repair in the 2.5 years I have owned it.
I lost the water pump at around 30K miles. So unless they are looking I don't think a tune raises any red flags.
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my question was more, what are the mechanical difference between the two? Are the engines and super chargers the same or different? From the factory, do they come with a different tune for the horsepower rating or are they mechanically different?

 

Exact same engine and supercharger from the factory, mechanically identical, the difference is entirely in the tune.

 

OzXFR, I thought the 575 package (maybe another for the 550 hp turne) got a smaller pulley to get a little more boost out of the engine. I know to get up to 620+ hp, you have to upgrade to the smaller pulley.

 

Nup, this has been discussed before, but even the 575 is mechanically the same with no change to either pulley.
Not entirely sure about the 600 PS engine in the Project 8, there are rumours that it has a different pulley but I have never seen confirmation of that.
VAP, Eurotoys and Viezu have confirmed that to go over 600 PS you need to change one or both pulleys.