Are the mods worthwhile ?
 

I continue to see posts on mods with pulley , exhaust and tuner changes. I also don't see to many that do baseline data gathering to see improvements. HP increases seem to be about bragging rites as the performance data isn't much significant from stock. So what is the real benefit here . Doesn't everyone run before and after dyno results and then go and get actual strip times. Just by the shear questioning of the results there doesn't seem to be much of a payback. So is it worthwhile and if so why.

Unfortunately I live in an area where dynos are about as rare as the Dodo and very expensive to use. I did not get a good dyno after doing the pulley mod, but I have dyno graphs for before and after exhaust mods, PCM remaps & meth injection. So far the result is very low to no power gains after each mod and after spending thousands of dollars.

I've had the pulley, tune, and a slight exhaust mod done, and I'm not sure there is much noticeable or usable gain. It's not thousands of dollars, though. Several of the tuner companies have run specials for well under a $1000 dollars, and the X pipe addition with the center resonator removal cost me $280 including the X pipe and installation. So, altogether I spent about $1100.00. The X pipe/resonator removal mod produces a great, subtle growl and was certainly worthwhile. The rest is more about ego.

Spent so far about $1k for all exhaust mods, $1k for meth injection, $1k for PCM map, $1k for dyno time, $300 for pulley and another $1k for various diagnostic tools.

I could never get traction in the 5.0 SC anyway so I have to say that unless new suspension and tyres helped with that first, I couldnt see any benefit from more power from the engine.

I did the x pipe as a mod (which I think did add a little power) but I did it for the noise, as the coupe is a little too quiet inside. The x pipe is a cheap mod for the difference it makes.

So the 5.0 L XKR gets 4.6 sec 0-60 while the XKR-S does it in 4.2 with 40 extra HP. What do the times look like for the tuner cars?

The 2008 4.2 XKR according to Motor Trend did 0-60 in 4.3 and 1/4 in 12.9 @ 110 mph.

With the current map it definitely feels a lot more power even if the dyno does not show it, I have a Quaife LSD, lowered & uprated springs, aggressive alignment and Michelin PSS tires so it sticks to the pavement quite well. I have not been to a strip yet as I have been waiting on a better tuned map.

Please excuse my interjection;

Michelin PiSS

Sorry, I was compelled.
Anyway, a BIG factor at any track is how well the first 60 feet are prepared and how warm the tires got during the DRY burnout. That can make a HUGE difference on times.

Same here , two dynos avalable in this town , and thay are not cheep to use .
And generally I'm at work working when these are avalable .
There are some really good smart phone/tablet apps which use the exelerometers to gauge G force , and gps to gauge distance and speed , you just add your curb weight and the app calculates the out come ,
I use dinolishous , it's clever , simple to use , consistent , cheep and always with you .
I have done Bosch 010 intercooler pump , 4liter intercooler coolant capacity increase , de gunked the charge cooler and TB , powerhouse 1.5 pulley ,
Manafold back 2.5" free flow exhaust with xpipe . 3" intake j pipe . K&N high flow pod with mina cold air box . (Also EGR bypass and PCV catch can no power gains here though)
I did do before and after 0-100kph times ,and quarter times , the before times and HP results were embarrassing . And showed my car was unhealthy .
7-8sec 0-100kph before , which would worsen considerably with repeated runs . From heat soak , supposed to be 5.4sec . Now 5.8sec.
My best quarter mile time before was 15.8 but mostly in the 16's (never really wanted to publish that) dinolishous said I started with 260rwhp so a lot missing .
At the time it was a stock unmolested nearly 2tonn car with 150000km .
Each and every mod made an improvement some more noticable than others,
Now runs 13.8' if I get it real right of the mark I've fluked a 13.4 and 13.6
Which is better than factory , and keeping in mind my car has 170000km on it ,
Dinolishous naw says I'm making 360rwhp , and I get two or three extra runs back to back before heat soak thanks to the IC pump and tank .
I can't help but think if the car was brand new with the mods I've done it may well be a considerable improvement over stock 400bhp . The car does feel great now as I'm sure jaguar intended , but all in all it sounds amazing and that alone was worth the $ in mods .
Exhaust was around $2k , mina box & K&N around $400 ,
Pulley was $300 , coolant tank and Bosch pump was $600
plus some coolant piping $100
J pipe and fittings was around $120. And the dinolishous app $12.
I'm hopeing for a tune via Cambo as well to complement the work done .
I'd truly be happy if I can reach 420bhp with high km's to Match the xkr's output from the same era , and much like Cambo I'd be thrilled to get this old jag in the late 12sec runs.

The XKR-S has different suspension as well. The suspension makes a massive difference, I'm convinced that my V6S F type is quicker than the XKR 5.0 was. Weight and transmission is part of it, but traction is the big difference.

Just looking at car reviews it has the V6 380HP F-type at 4.9 0-60

I posted this in the other thread, seems like the right place to post it again, given the subject matter.

I had a chat about this exhaust/cats subject, with my ex-JLR friend who writes tunes.

Here's what he said;

-------------------------------
⁠⁠⁠Exhaust backpressure is very important on the torque based PCM's, i.e. the 2006 onward models like an X150, since this parameter is used to calculate engine VE (volumetric efficiency).

So, put in an x-pipe or remove the cats (or install 200cell, 100cell, etc) and the fuelling would be off, because the VE of the engine no longer matches the stock parameters, resulting in high LTFT/STFT %'s.

This would limit the perfomance somewhat and/or cause some hesitation in certain RPM/load regions.

VE, in turn, is used in the torque calculation (driver demand, calculated indicated torque, which are compared to the estimated torque table in the PCM). In HEAVY cases SOMETIMES it may even trigger limp mode (been there, done that).
-------------------------------

And this makes perfect sense to me now, since we had the experience of flashing the factory XKR-S tune into a standard R and it did not make good power. Yet we have also flashed the stock XKR-S tune into other cars that were fitted with the XKR-S exhaust (with the x-pipe) and it made great power.

There are dozens and dozens of maps/tables and factors in the PCM of the X150, even things like the supercharger pulley ratio are in there and can (must) be modified. So with an X150, any mechanical changes you make to the car, be it exhaust/cats, pulley's, intakes, they have to be acommodated for in a custom tune.

Yes the PCM will adapt somewhat, but it won't be perfect, and in some cases I guess you could even go backwards, if the tune is not matching the mechanical changes.

I guess I would have to ask why Jaguar went with 2 different exhaust systems on the same model car. My XKR has the stock performance active exhaust (X-Pipe) with just a back box while other XKR systems have the twin resonators and the back box . So what is the difference in power/performance between the 2 systems and do they tune each car differently. Will an R-S tune with a PAE give you the 40 HP improvement ? Do the PAE cars have more HP or do the non-PAE cars have less HP

Lots of reasons I think. Cost, sound, performance, marketing purposes, etc...

Which is the same exhaust as the XKR-S.

The PAE system obviously flows better. Also the x-pipe has a positive effect in that it compensates for the firing order of the engine, where two adjacent cylinders on each bank fire in succession. By "joining" the exhaust pipes of both banks, the build up of back pressure from the two adjacent cylinders is minimised. The x-pipe helps to bring power in the upper rev range. I will have to check about the factory tunes, I never thought about this earlier...

Yes, absolutely. Actually it's a little bit more than 40hp.

I don't know of anyone who has done back-to-back dyno's to confirm this, the only dyno i've seen was an XKR that was retrofitted with the PAE exhaust and flashed with the XKR-S tune, but they did not make a run with the PAE exhaust and the stock tune, only with the stock XKR exhaust beforehand...

a 12 XKR with factory tune and pulley got a Spires stage 3 in UK and was dyno'd at 531 HP. an XKRS on the same day on same dyno got 550. Seems the added exhaust is a nice gain in HP and a tremendous gain in FUN! lol

Lothar,

First, nice to meet you. Not sure how to message you direct but I live in Cincy and just bought a 2012 XKR and would love to connect with you as I am doing the spires stage 3. I was interested in the pulley and tune but wanted to know if you got that done up in Columbus and had any recommendations, etc. Also would love to pick your brain about the car, things to look out for, check, etc, etc.

Appreciate it.

Christian

NO

It would be worth doing - mainly for others than the owner!

The cost of the upgrades is quite high yet people don't do before & after dynos. Odd.

As far as I know I'm the first n/a xk 4.2 to run a 13.72 so yes in my opinion a free-flowing exhaust and a specific ecu tune has dropped my et by .8 and increase trap speed by 6mph so mods definitely work.

So, the question is, do these modifications actually do anything? Well I guess it depends on where you spend your money.

I haven't put my XKR on the dyno, it's cheaper for me to go to the track for the night, and the last time a dyno sheet was posted on this forum some genius tried to pick it apart, and he was wrong.

And we can't race dynos anyhow.

So let's look at my XKR, have the mods been "worth it" ? The numbers speak for themselves.

Not long after I got the car, gave it a big service and put on new tyres, i went to the track.

Did 13.184 @ 106.68mph, 1.950 60ft

Then I realised the cats were choked, so I changed the cats, put on the straight through exhaust with x-pipe, had the tune corrected to compensate for these changes.

Did 12.943 @ 111.57mph with a 1.998 60ft

Then I got the tune re-worked to squeeze a bit more out of it.

Did 12.646 @ 113.97mph with a 1.975 60ft

So i'd say the whole exercise has been worthwhile, it's been a lot of fun too, and we're not finished yet, I haven't touched the pulleys, or the intercooler...

Without wanting to start a war, not a single "mainstream tuner" has been able to get even close to the results i've gotten so far with the 4.2L XKR. They can post all the dyno sheets in the world, it's not the same thing as rubber on the road.

Ultimately, yes, it could probably be argued that certain mods or tunes from certain companies are not worthwhile. On the other hand, here's my XKR...

That's pretty amazing and the fastest 4.2 X150 XJR I've seen from memory. Almost the same mph as a twin screw X350! Well done.

I wonder if matching the 12.3 at 119mph of a stock 5.0 xkr is possible with further mods? Is there a specific reason you're going for a larger crank pulley as opposed to the usual 1.5lb supercharger most have gone for? I'm guessing it's a EAPJ one.

In simplest terms once the top pulley gets small enough it'll start slipping. Surface area of the ribs x belt tension x friction coefficients = torque. Smaller pulley, less surface area.

Thanks man!

The 12.3 @ 119mph was the XKR-S GT, the quickest stock 5.0L XKR i've found was a 12.2 @ 114mph. That shows you how much the 5.0L get's throttled back / torque limited with the stock tune.

I think a 12.3 from the 4.2L will be tough, and I have no interest in Nitrous or time/budget for fitting a twinscrew.

That was one of the reasons I wanted to go for the crank pulley, the other is that it's a bolt-on/bolt-off affair, if I change my mind or the performance goes backwards, I am not stuck with it...

I have to jump in here. I have numerous mods (take a look at my signature) and indeed they are worthwhile and make a difference in my particular case, some more or less than others. But I really did not notice gain the full benefit of these changes until I was able to do a proper re-map of the ECM & TCM. After several years of searching and researching, mostly looking at what others experiences were here on the forums, in 2016 I settled upon a respected vendor for a tune. For the investment, the result was less than impressive and the tune itself had a number of faults. I gave up, frustrated and angry. Then I came upon Cambo and his tune and the results were both spectacular on paper (dyno before & after) and on the street with a gain of about 80ft pounds of torque. Even with the Quaife LSD, I had to drop the MPSS tires in favor of MPS Cup 2s just to stick to the road on launch. Now the recent latest version I am running is phenomenal and will snap your neck with no hesitation as it propels from 0 to 70+ in seconds. I haven't had a moment to do another dyno pull but everything is telling me incredible gains such as the Sport Cup 2 tires are no longer sticky enough and methanol injection kicks in at lower RPMs and for longer duration than it did previously. Anxious to get to the track for a slip this season. Will post once it is in hand. Also still need to get custom front intake ducts fabricated and further exhaust tuning.

Car and Driver figured a 2010 XKR 1/4 mile at 12.3 @ 119mph:

https://s3.amazonaws.com/amv-prod-ca...short-take.pdf

Maybe they got a particularly good example.

It seems way too good when you look at the 1/4 mile results from 5.0L XKR owners on this forum, for example https://www.jaguarforums.com/forum/x...vs-tune-76368/ that bloke knows how to drive too...

119mph trap speed is XKR-S territory, not XKR.

These are two actual 5L xkr that can be 100% confirmed as we have footage

12.31 @116mph (xkr)

12.24 @114mph (xkr convert)

Considering Cambo has run a legitimate 12.6 @114mph in the 4.2 engine variety with no pulley upgrades just a tune,LSD and free flowing exhaust its nothing short of amazing.

He's knocking on the door of 5l power.

Smoked that M5, disregarding the horrible start.

Cambo, I've changed the exhaust on my otherwise (effectively) stock 4.2 XKR. I've got an x-pipe mid section without the two small silencers/resonators and I've changed the back box for a smaller one. The information you posted from your contact there suggests that these may be material enough changes to require the ECU software to be adjusted to suit, is that right? Is it a case of monitoring trims to determine if they are now excessive and if so, what sort of values should I be looking out for?

I've never seen any fault codes related to that stuff since I did the exhaust modifications but I guess it'll only log codes if the trims go out above or below a certain range of values...

Maybe, but yes you would need to look at the PCM fuel adaptation data with SDD to know how far out it's gone.

It might also be that with the stock cats, and a lot of miles on them, they are choked up enough to increase the backpressure, and the new free-flowing exhaust is not making that much difference as a result.

What I can tell you, is that after changing out my original choked up cats, and putting in the straight through centre section with the x-pipe, the car actually lost a bit of power & responsiveness, mostly in the lower rev range, it just felt sluggish. After flashing in the corrected stock tune (all fuel, spark, limiters, etc stock, only the exhaust backpressure values changed) it felt like a totally different car, and went like one too, that was when it did the 12.9 @ 111.5mph, which was a fantastic result compared to the 13.2 @ 106.5mph it did "stock" prior.

Right, you won't get any codes unless it's miles out.

Thanks for the input. The car is showing about 93k miles now so not inconceivable that the cats (stock and original as far as I know) could be the bottleneck here. As regards using SDD to measure the trims, is that possible without the measurement module hardware? If so, can you point me in the direction of some instruction as to how to go about this?

If SDD is a no go without the hardware, I do have the Torque Pro app and a bluetooth OBD2 adapter, I could at least get whatever is presented in standard OBD2 format over that bus.

Even a cheap OBD tool with live data (elm327 etc) will let you look at trims. £5 and up.

I have one of those and yes, it does using Torque Pro. But there are often manufacturer specific oddities with apps that read generic OBD data so I'm not sure if this is one of these, and I need to know what values I'm looking for anyway.

IDS/SDD gives you a much more detailed view of the fuel trims in the 2006MY onward cars.

Attachment 205595Attachment 205594

Note that in the 2nd pic a lot of data is missing because the car didn't do enough miles at that time after the PCM had been reflashed (which cleared the adaptations)

Thanks Cambo. Do I need the measurement module hardware for that? In either case, is it just a case of reading the values, or should I clear the adaptions and do some mixed driving for a couple of weeks and read the values after that?

No it's just read over the OBD port, with a VCM, DA-Dongle, etc... you do not need the VMM for this.

If you clear the adaptations it does take a while for the re-learning to be completed, when I took those pictures i'd driven 300km since the reflash, and they were still not complete...

OK, I changed my MAFs a couple of months back (maybe 300 miles in that time) but I didn't think to clear adaptions back then. I'm not an expert but I'm not seeing anything in those screenshots to say that the relearning is complete, or is it not shown there? Is it a case of covering a certain distance after clearing adaptions?

You see the black boxes in the 2nd pic of the LTFT's, it's not recorded any values yet.

OK thanks, I'll look into this, cheers.

.