I did the velocity AP tune and pulley on a couple of different XKRs, most recently last year It's interesting that Stewart is now recommending both upper and lower pulleys on this engine, because last year he recommended only the crank pulley. Said the supercharger pulley was not really worth the effort or expense. In any event, the crank pulley was definitely worth it.Yeah there's some people on these forums who will scream bloody murder any time you mention making aftermarket modifications to a car under warranty saying that you won't be able to get pivi pro fixed if you do something like that. However, I've done my research and I'm 99.9% sure that modifications made to the powertrain will have no effect on the warranty for things like speakers or PiviPro. I think there is a big misconception out there that once you modify your engine you lose your entire warranty. Also, people like to assume that as soon as they find out you have a tune your powertrain warranty is voided. When in fact, if the whole lot of fpaces is experiencing problems with fuel injectors and your tuned fpace has a problem with fuel injectors then you can argue that it is not tune related and thus have it covered under warranty. It is when you start to experience problems that other nontuned SVR's are not experiencing that you are out of luck. Even then if you have a cool dealer you could still be covered.
Ahh I don't have these problems in Arizona, just excessive heat issues which can be easily solved with meth injection. I'm planning on doing a stage 3 Velocity AP tune with upper and lower pulley and I'm feeling very confident in the modification as VAP has done extensive testing and shared that JLR ran the engine between 750 and 800bhp during testing. Stage 3 will put me at 660hp and 630tq.
Now that I think of it, though, the difference may be that the ecu on the XKRs is harder to tune because the operative chip can't be adjusted as finely, while the newer SVR set-ups in coupes and SUV form have a different ICU that allows for better adjustability in fuel and spark curves. So maybe that's the difference here....I'm not necessarily doing it out of recommendation but I've done a lot of research on the f type forums and people seem to come to a consensus that the single pulley is perfect for the f type with a select few running the dual pulley system. So I just figured with our additional weight that the extra 33 ft/lbs of torque and 15hp for $200 more certainly would not hurt. That torque is 40% extra torque than you would be receiving with just the single pulley. Adding meth injection would give it a slight boost as well while keeping everything cool. All said and done that's $2500 for everything I just listed.
Makes sense, but what Stewart told me was that the website numbers were "very optimistic" and the "real world" numbers were likely much lower, with more stress on the supercharger for maybe 10 ft-lbs. more, if that. Maybe he just didn't want to do the work at the time, I dunno...
