I have a 2016 XJL-R 5.0 and I want more horsepower than 560. What is the easiest why to do this ? What's is the most horsepower I can get out of the car?

 

I take it your a young guy , why do you want more than 550 horsepower. Their is a tuner on here , can't remember their name but a big multinational company found mostly on the F type section who could help you , I am based in the Uk , are you stateside. I had an xkr many years ago and got a vap tune stage 1 on it took it to same as yours but quicker coz the car was smaller and lighter a couple split seconds faster , on the f type section their is a few who have got a stage 2 vap tune , and changed both pulleys , plugs and cat cells giving them 700 bhp , some guys on this section have also done similar, so maybe they can advise better , I have just changed car myself , had the v6 xjl supercharged autobiography model giving 340bhp . very rare car in the uk , but got told from my friends in jaguar Uk regarding one of 18 v8 supercharged autobiography cars in the uk , had a test drive and love it , take possession next week it has a measly 510 Bhp , very happy old man . could have gone with the 575 model but here in the uk they don't have the rear seat package , tv tables , foot stools , reclining rear seats , ilumanated every thing

 

Not to young im 39 and I am in Texas this was my dream car for a long time . I am hoping to one day to get the 575 and have both of them since the US is making a lot of changes to the emissions regulations. I really like Jaguars they are really underrepresented. Thank you for your help!

 

VelocityAP is what you want. You can do a supercharger pully + tune, remap the trans which reduces 1 shift up to 60, and do things like 200 cell sport cats, cat back exhaust, and Mina gallery intake tube, and you'd be around 650-675.

 

Keep in mind that you can have all the power in the engine, but you need to get it to the ground. I seem to remember that the 8HP70 trans has a structural limit of 516 ft-lbs. You start going above that and mechanical components start breaking. So, keep that in mind.

To get up to 620 hp is really nothing more than a new pulley on the supercharger and getting the computer with a new tune. That as I recall puts you pretty much at that magical 516 number. Going above is flurting with disaster. I am sure you can upgrade parts in the tranny as it is a ZF tranny and there are parts out there for it. Just not sure what it would cost to do what you are thinking of.

 

Do you know the torque limit for the earlier 6 speed ZF?

 

XJ-SS, from reading other posts here, the 6 and 8 speed ZF trannies are both rated for a maximum of 516 ft-lbs of torque. Reading, others say that you can push it beyond that without any significant risks. The number that most were calling out was 550 ft-lbs. Yes, 550 is more than 516, but at that point, this is kinda insignificant. Which you could then say that going from 510 hp to 600 hp is "insignificant". is it? All I can say for sure is XF has published that the limit of the tranny is 516 ft-lbs. I am sure members have pushed the tranny beyond that and I am sure if you were to put in say a stage 2 or stage 3 shift kit into the tranny, it may take more torque as it is now not going to slip the gear as much, therefore reducing the amount of heat the tranny makes which is a big killer of trannies atleast for longevity. Cannot speak for how well the metal parts are going to withstand the harder shifts and/or additional power. This will be one of those things that you have to see what others have done, what power their car is making and then make a logical decision on whether you are willing to take on that risk. I hate to say that breaking a tranny would be a "good thing", but that would let you know the weak link and then you can figure out what you can do to strengthen that part which in theory should allow you to go higher in power before something else breaks. But, now you are going into a space that each step is an unknown and how much money are you willing to spend to be the first to have something? I know I treaded into that water when I put 37's on my truck with only a 4" suspension lift. But, I also did it with some pre-planning and measuring to know it would work. I knew the drivetrain would handle the tires and the new gearing. It was just a matter of making sure I had the clearance I needed.