There was a multi-page discussion on this before.

I'll add and echo DGL's statement around ETG illustrating exactly what is being tuned and some solid examples of XKR/S's having been tuned and dyno'd.

As Bruce says, if the tune is restricted or mostly cancelled by the TCU limits there is obviously no reason to spend the money. If the AFR is leaned out too much this is not good.

So, does ETG not have the data? Do they not have the information? Do they not want to share specifics and just keep going as they are? They may be getting "enough" business with their current modus operandi.

 

Yes, I read through it 6 months ago. With no 5L SC XKR's to report on the ETG tune, at that time, I did not want to take the lead.

We now have some 5L SC cars fitted with the tune. However, no one is boasting of how good it is? If I had this done and the results were good I would tell everyone how good it is. Seems to be too risky with very little gain, if any, and $2,000 less in your pocket.

 

I think the TCU is even restricting stock torque levels from ~3000-5000 rpm. Thats where the increasing torque curve uncharacteristically goes completely flat as opposed to continuing to rise and then gently fall off, forming more of a traditional bell shaped curve. The variable valve timing would contribute to keeping torque up at higher rpm, but not to make the torque output go completely flat. This has to be the TCU's effect, and done to protect the transmission. I recall hearing that another manufacturer did have problems with this same ZF tranny breaking under high power, and torque limiters in the TCU would be the fix to avoid failures and warranty liability. BigCat09's previous ETG remap without TCU adjustment did make slightly higher torque, so the TCU limiters can't be at a fixed torque level, but rather somewhat variable. That would account for the XKR-S making a higher claimed torque also, likely caused by a very slightly leaned air/fuel ratio and reduced back pressure in the manifolds and exhaust system.

I've always suspected that there are probably one or two suppliers for most of these off the shelf high performance car tunes. No one man operation could possibly access all these factory tunes and remap them. That would also explain why they can't give details or produce dynos.

Our traction issue starts with an enormous amount of torque coming on below 2500 rpm due to the operation of the supercharger. It simply over loads the tires grip at that rpm where the car is either at stop or low speed. Cars with turbos increase torque slowly when you go full throttle at lower speeds and don't break the tires loose so easily. If we want to grip better we need to show more restraint with the throttle, get the tires warmed up to give more grip, and go with a stickier tire compound. Also, our throttles are more like a hair pin trigger, lacking some linearity between throttle pedal angle and power increase. That's likely a software issue done to make the car feel very responsive, and it's much worse in "Sport" mode. Our roll bars, spring rates and damper valving/programming would also be optimized for comfort and overall handling as opposed to hard launches and optimized 1/4 mile times. Torque applied to the drive wheels is also determined as much by gearing as it is by engine output, and our 1st gear is certainly an over-achiever. You've heard me praise the stock Dunlops on my XKR, and that's partly because they grip extremely well when they get fully heated on the race track, and because they lose grip predictably and progressively when pushed to their limits. Unfortunately their limits are much less at lower and normal temps. And the car's high weight certainly prevents it from accellerating as fast, turning much of that torque into tire smoke rather than forward thrust!

Bruce

 

Here is a link to the before and after dynos on the ETG tuned XFR.

Jaguar XFR ECU Tuning | ECU Tuning Group

Looks like the overall TQ band was up about 50 tq if you are not just looking at peak numbers.

HP looks to be up around 65 hp, almost across the entire band.

If the TCU kicked in, it still looks to have allowed a healthy TQ gain from 3500-6500.

Thoughts?

Edit: Found the TQ ratings for the ZF6HP28 tranny. Looks like it states a rated input torque of 326 to 444 ft lbs, model specific. Maybe this is another reason why Jaguar chose to keep the XKR-S GT at the same power levels as the XKR-S? Seems they are right on the edge, as is. Of course ZF is probably being very conservative as well.

http://www.zf.com/na/content/media/u...28_Catalog.pdf

 

Interesting. This seems to support my "butt dyno" sense that the car pulls harder in the mid range and up after the tune.

I had not seen this chart before, although I don't know why not, because I thought I had perused Jags' website pretty carefully. So the reality is that he has in fact published before and after dynos on the 5.0 SC engine, although in this case the "before" isn't stock (as it includes a pulley and exhaust), and the "after" therefore seems to show only the effect of a flash...

 

I wonder why his torque numberrs are so low. We are getting 460rwhp & 460 ft-lb of torque @ 3600 rpm with the torque curve staying above 400 until 6000 rpm. This is with a 1.5lb pulley & custom tune. I will be glad to post the dyno sheets later.

 

For some reason, the XFR dyno is in the blog section of his website, and not on the dyno's page.

But the results don't look bad at all. I also wish it was stock vs. pulley/tune.

 

I would definitely like to see your dyno sheets.

Who did the tune? Do you have any thoughts on the transmission control unit trying to cut/regulate power?

I have no idea what the loss ratio is on these cars. Makes me really wonder what a stock XKR-S should see at the wheels on a dyno.

 

You shouldn't be...I explained it enough times The engine and setup is completely different on your older model, and those results have no bearing on the 5L.

Bruce

 

I believe the torque converter on the R-S (and my 75) is an uprated version, which is why Jaguar was happy to lift the TCU limits. I would expect that any standard XKR will probably be TCU-limited, unless someone's hacking the TCU as well.

 

I don't understand I thought this was about 5.0 supercharged cars. The info I posted had nothing to do with my car as it has never been on a dyno. The numbers I posted came right off dyno sheet from a 2012 XKR we tuned this summer.

 

Okay, perfect, that wasn't specified. Please post your dyno with details.

 

Those are BigCat09's dynos that were posted in the XFR forum. And they actually are stock vs pulley and flash, not pulley with and without tune. The graphs also show the leaning of the air/fuel ratio with the tune compared to stock.

Bruce

 

I have received the other dyno sheets from Jaxkr and I can't see the tcu limiting the torque, it looks normal to me. AFR's look more conservative on his tune and probably because of that it is off peak power a tiny bit.

Actually, I suspect the AFR's on Bigcat's dyno sheets are off a bit. Even in stock form they look kind of lean. Possibly the sniffer wasn't calibrated or it was off in some way. Looks like the AFR scale is different between the two as well.

 

Matt, can you post those? What do the curves look like vs. stock? AFR's are a little rich? Whose tune is this?

 

I wouldn't mind posting them but since they belong to Jaxkr I think he should make the call.

It looks quite rich actually from about 5300 RPM +

 

Ok. I've PM'd him. But would still love to know who created this tune for which he has sheets. Is it ETG?

 

No it's not ETG. I believe he said he is affiliated with another tuning company in Europe. He said I could post the sheets so I am going to scan them in and I should have them up soon. I'm about to leave work and drive home now.

 

Okay, here is a better copy.

 

Great. Thank you.

Well, it sure would be hard to argue that those AFR's are any concern at all. In fact, as you say, there's surely hp still on the table at some points in the curve, because near the top at least it's pig rich. Yet the gains over stock are clear and significant. Does he have the "before" sheet?

One aspect of the sheet that rings true to me is the torque rise at 3500 rpm. That is what I have felt, albeit on a tune from a different source....