Cambo. No one ever said all Dyno’s measure the same. Just the same as all drag strip runs are not the same. Different track and different weather conditions, reaction times WILL yeald different e.t’s. You know that as well as everyone here knows that. So to say drag strip is the only true way is nonsense. I am pretty sure that everyone is aware that dyno’s all read differently dependent upon type, brand and operator etc. my point is not one tuner has ever released a before and after Dyno runs on the same dyno on the same day under similar weather conditions for these cars. If tuning was my business and I was trying to sell tunes to my customers, I would certainly use the dyno charts as validation of my work. Unless of course, I had something to hide. Now, I certainly am not saying this is the case with your tunes and they may very well be the best but my understanding is that it takes maybe 30 minutes to install a tune yet not one tuner has published before and after results on the same day on the same car and same dyno for our cars. What are your claims for your XKR-S tunes ?

 

Mufc, I think you are missing a couple huge points. As has been mentioned in several other threads, no one really understands how Jaguar built the tune for these cars. There are layers of variables that need unraveled and sorted out to determine if changes actually improve performance or just push the power plant closer to 'boom'. What a lot of the F type folks found out to their detriment was some tuners really didn't have a grasp on what they were tweaking which put the engines at risk. That's where the XKR-S tune comes in. It was factory designed and once copied could be sold as 'Custom' or at least the basis for a custom tune. Again, Jaguar did not share any info with the aftermarket like Ford did in the early 2000's so it's all guesswork about what variable hold what factor of control over the basic tune.

I would hope and almost expect there would be a ton of relevant experience out there for my '07 Since it's been on the street for 10 years but there doesn't seem to be much and certainly not much that goes beyond a sales pitch

 

As someone on the forum primarily as a Jaguar owner (XJ8 and XK 5.0) I'm really don't want to get into forum battles, especially with a moderator, but not ALL 4.2 XK engines can be remapped through the OBD port. It depends on the year. The latest Alientech listing (for Kess 2) shows only certain revisions of the ECU have OBD read and write. Others are K-tag boot only. Take a look at their January 2018 charts and you'll see. I don't know why you think that 7% is plucked out of the air either. On what basis would that be your view? Finally the 'remapper certification courses' that you put in italics implies that comes out of thin air too. The courses are the IMI (Institute of the Motor Industry) courses. In a world with no other measure of qualification to perform remaps this is a decent measure of a remapper's abilities. There are so many people buying clone equipment with a disk-full of maps the IMI decided to take action for the benefit of buyers. It doesn't mean remappers without the IMI Certification are not good, as many have years or experience gained before the IMI Certification came into being two and a half years ago. but it does show that an individual has taken the time to become certified and has had formal training on safe processes.

It is unfortunate that while trying to help and provide some information for those that are interested in remapping I feel I have to defend myself against an unexpected and unwarranted 'attack' from a moderator. I remap over 500 vehicles a year. It is a full time job, not a hobby. If I have permission to state my company name I'll do so, and you'll see every review on Google Reviews is 5-star. If anyone wants to contact me I'll be happy to help but I won't take advantage of a forum by blatantly advertising. I'm mainly here as a fellow Jaguar owner rather than for business.

 

I'm considering a tune with my 2007 XK N/A 4.2 engine. I more interested in improved throttle response than in horsepower gains. Did your 2012 N/A engine feel more responsive with the tune?

 

Your 2007 XK is now 12 years old and a lot of different things can happen during that time to cause a loss in performance. Before doing a tune, get your XK thoroughly checked out by a competent Jaguar technician.

Several years ago, I noticed that my XKR felt a little sluggish, but I didn't have a CEL or restricted performance warning. I was still under warranty and had my dealer check it. They found that one catalytic converter was partially clogged and replaced it under warranty. It didn't feel like the same car afterwards, and had much sharper throttle response. Doing a tune before replacing a bad catalytic converter would be throwing your money away.

 

Thanks for the response. I think the cats are OK since the car seems to move good enough. It's not terribly sluggish. What I'm looking for is a little more crispness in the throttle. Maybe I'll just put my foot in in a the pedal little more. (Smashing the pedal does seem a bit excessive.)

 

X-pipe, 100 cel cats and a tune has put me at 13.72

Yet to go back since installing the large throttle body and shorter diff ratio

A tune is definitely worth it and now on par with the 5l n/a

 

Looks like you achieved some good results. I'm thinking I'll start with just a tune then build from there if needed. An X pipe or throttle body would be next. I don't think I'll need to re-tune the car with each upgrade since the car is intuitive and will adapt to my driving habits. At least I think it adapts.

I know I could eventually buy an XR but I will be happy to get my 4.2 N/A running at its optimum best. That would be good enough for me. Once the car is tuned I'm hoping it will have a more responsive gas pedal and launch the car from 0 to 60 in well under 6 seconds.

 

The Denso PCM (Powertrain Control Module) in the 4.2L X150 has some very complex strategies, it will not adapt to major mechanical changes, the tune has to be adjusted for just about any changes you make.

For example if you change the exhaust and fit high-flow cats, and leave the stock tune, you will probably lose some throttle response, because the backpressure in the exhaust is one of the values used in the torque calculation by the PCM.

After fitting the Maxbore throttle body to Steve's XK the car would not idle properly, the tune had to be adjusted for that, and it took a fair bit of time to sort it out (measuring the throttle body, calculating the surface area, etc).

 

Just had a read back through this thread, I had to laugh...

Add 12.463 @ 115.36 with a 1.959 60ft to that progress report.
I got it to trap 115.5mph a couple of times as well.

And this actually happened LOL, u102768 ended up with 11.930 @ 121.3mph on the slip from his 5.0L XKR

Who needs dynos...

 

I went from 369rwh to 434rwh and even more torque, on my 08 4.2 XkR with my tune and high flow cats vs my car with pulley only upgrade . So if you know what you're doing there is definitely power over a factory tune. On the other side, a tune on the same car from Eurocharged gained a misely 7 rwh. I went from 13.3 to 12.6 1/4mi on the same Las Vegas slower track . Big big difference in power .
and yes our cars can be reflashed through obd2

 

Saw an XKR 5.0 dyno 505WHP (I believe) at Eurocharged Orlando on their tune.

Had my XKR running VelocityAP and it was a massive difference vs. stock. Not even the same car. When I traded the XKR for the R-S, I can tell that the tune on my XKR was a modified R-S tune.

With VelocityAP, you're getting about 575HP (which is basically the SVR state of tune). Add the pulley, you're at ~600.

 

I know that there isn't much point comparing results from different dynos but my '10 XKR had just under 503 WHP with just the XKR-S tune and the XKR-S mid pipe on it so I would have hoped for a little more from a tuner, especially if a smaller pulley was put on the car as well.

 

For years tuning companies were claiming xxx horsepower from the cars they tuned, showed dyno sheets with "great" numbers on them, but the actual performance of the cars never matched up.

"Tune + pulley 630hp" but when people took them to the track they didn't run any faster than stock!!!

It's gotten to the stage where dyno sheets aren't worth the paper they are printed on.

The 1/4 mile trap speed is the only proof of horsepower that I have any faith in, it's pretty simple physics and the methods apply across the board.

If your 4.2L XKR is really making ~500hp then it will trap 115mph, like mine does.
If your 5.0L XKR is really making ~600hp then it will trap 121mph, like u102768's does.

I don't care what a dyno sheet says, those are the real world numbers that cannot be fudged.

 

I fully disagree! Your forgetting correction factor for DA altitude which is used on all Dyno readings and is used by most drag racers to compare track to track numbers as conditions make a huge difference. Also you are forgetting track conditions, head winds, unpreped track, slope of the track and so on. Every drag racers knows there are fast tracks and there are slow tracks. I ran13.8 for example on my old w210 e55 on a track with near 4000 DA altitude , corrected for DA the actual time is 13.1 and 5 mph higher trap speed.
My last time running XKR at Vegas I ran 12.6 and 110.3 ,not including that Vegas track is up the hill plus strong head winds that day, da correction only is actually 12.47 and nearly 2 mph higher. Plus my car is a convertible and weights 100lb more than a coupe, which is aprox 1/10 of a sec difference in weight alone on a 1/4mi. Density Altitude is why most drag racing records are set during fall when air is dry and cool and near sea level , but not too cold where you loose traction. Bottom line DA is very important as well as track conditions. Dyno is definitely a more consistent and precise tool to measure HP and not a track where there are too many variables and why manufacturers use a Dyno machine and not 1/4mi to get power figures.

 

What a breath of fresh air some of the new comments are. For years and years I have been telling my customers that the road test is more important that dyno figures. Most drivers want to feel improved responsiveness and low-end pulling power improvements in particular.

The most common pre-remap request I hear goes along the lines of 'if it improves power at high revs, and once the car is going, that's great, but can you make it go when I tell it to and get rid of, or reduce, the lag". That is why I have always promoted a post-remap road test before payment, and why I offer a 30-day money back guarantee, I must add I also fully understand why drivers are sceptical about claims without seeing dyno results but by the same token dyno results are very easily manipulated, whereas a road test by the owner is definitive.

My own XK 5.0 responsiveness and low-end power improved dramatically after the remap. I will get it back on the rolling road in April or May (after it comes out of Winter 'SORN' which, for non-UK drivers, that means it is declared off road at the moment to avoid paying road tax in months I am not driving it) and will publish the Dyno results here. If anyone would like to attend to verify the test they're welcome to contact me.

There are owners that care about the numbers on the chart, and there are owners that care more about the on-the-road experience and drivability. In reality, it is the latter that really matters, but I'll get that Dyno read-out up as soon as my XK is back on the road after avoiding the winter salt! Until then, please bear with me.

Cheers.

Paul

 

I always looked at it as dyno numbers are Boasting rights while drag strip numbers are Bragging rights. Either way I respect the numbers.

 

Track MPH is HP, time is efficiency. Takes a good bit of HP to go faster in the quarter mile.

 

Although I currently own a 2014 J, I just purchased a 2015 XKR convertible. It currently has no mods. Based on this forum I my add an x pipe and air intake. With that stated, should I go for an ECU remap or the less expensive and unidentifiable "Chip tuning" (still under warranty). Any recommendations on either. Keep in mind I'm in Chicago so it will be a DIY.

 

Hi Powerhouse, where did you get it done? I'm in Ireland myself and I was looking for someone with a bit of experience on these cars.