I guess avos could put a price breakdown in the For Sale section... Not really in here, I again guess.

At about $7K (seems to me a fair price) we're not talking many buyers.

 

Avos, your kit has an adaptor plate between head unit discharge and stock jag IC inlet manifold with 'V8' mark on it.

Making adaptor plate between stock TB elbow and Kenne Bell inlet is cheap option but hurts airflow. New inlet needs to be CNCed there. That makes problem with bypass valve that needs to be smaller than stock and relocated.

TB bored out to 82mm is nice option but not obligatory for 500-520 crank HP I'm going to reach. My unit is 2.2 KB so I would have to overspinn it to get more, that is doable but not reccomended.

 

Been slowly gathering parts to rebuild the suspension. Shock bushings were shot, shocks were tired and the front springs were sagging (car was down about 1.5" in the front). The lower shock bush has pretty well disintegrated which made the car feel very vague and unnerving on center.



For the front:
New OEM springs are nowhere to be found so I opted for Adamesh lowering springs which have the smallest drop of any I found (25mm). Powerflex bushings and upper mounts had been done about a year ago. Should have just done the shocks then, but oh well.

New R package shocks, spring pans, XKRacers super titanium sway bar end links. Also got the R package steering rack bushes and tie rod ends, since they were not very expensive, but these parts were in good shape so I saved them for later.



For the rear:
All new bushes for the panhard bar and cross member mount. Adamesh springs, mounts, R package shocks and all the rear diff mounting bushes.

Also got an Ultra Racing 20mm sway bar and XKRacers end links for this end as well.



It's a good workout with the spring compressor but rebuilding the front shock assembly is pretty strait forward except for that someone had put thread locker on the shock nut which made it a real b*tch to get off. Best advice I can give is to put the bump stop and boot in plain sight so you don't forget to put it in and have to compress the spring again.

All back together, looking a lot nicer and the car feels great now. The "lowering" springs actually sit a little higher than the old saggy ones. The rode is firm and responsive but not harsh at all.



Haven't done much with the rear outside of installing the sway bar and end links. The other bushes require dropping the rear suspension assembly and I am waiting for the LSD install before going that far.

The sway bar really toned down the side to side wallow and makes the car feel more balanced. The size difference is only 3mm more, 17 to 20mm, but the stiffness goes like the square of the diameter, so it's almost 40% stiffer.

The brackets needed a little tune up to fit the mounting holes properly but this is one mod that is easy to do and makes the car feel a lot more sporting, IMHO.

 

Finally put on a MacLeod Performance X-pipe exhaust system. 90% of the work was getting the old one off, once that was done it was a breeze to install the new stuff.

Thanks to everyone who had advice about removing the old system. The clamps were not so bad once I found the trick and I was able to remove the old system (mostly) in tact.

The car has to be quite high off the ground to rotate the over axle section far enough to get it out and I ended up cutting it. Makes it very easy to see the squished section. That's terrible, I can't believe they did that from the factory!

By far the worst was getting the studs out of the mounting flanges on the cats. The new system is a 2.5" pipe but bolts up to the stock flange so the studs and nuts are replaced by hex bolts that can sit a little closer to the new pipe and still turn.

4 studs came out in 6 pieces. I didn't have to drill any of them but it was definitely some quality time with the torch, stud extractor and a big breaker bar.



New X-pipe section replaces the center resonator. 2.5" 304 stainless pipe, very well made and substantial. Looking down the X it is a pretty clean opening and a strait shot through to the other side.



All bolted up is fits well and looks very nice. Almost a shame to put it under the car. The under axle sections are tucked up nice and close, so don't really affect the clearance too much.



Exhaust tips are nicely made, simple ovals and just a little larger than the stock single tips. They fill out the openings quite well.



The wife and I take the car on long trips and wanted something that wasn't going to be bothersome at highway speeds so this is the quietest of 4 sound level options. There is also a Euro spec that adds two resonators just after the X section if you want something even quieter.

The sound, well it's totally different than stock and she sounds like one very bad cat now. Very deep and throaty sound.

At Idle and highway cruise it's hardly even noticeable inside the car. There is a little snarl at moderate acceleration and a serious but refined sound at full throttle.

It used to be all blower whine, but now it's a lovely symphony of intake and exhaust sounds.

Haven't driven the car too much yet, but I'll get it back to the dyno this winter while conditions are comparable and see what difference the exhaust makes.

Not that I am hoping for anything huge, am plenty happy with the power as it is, but I'm curious how much restriction that squished section really was.

 

Nice you keep eye on your cat :-)

Don't want to spoil your enthusiasm but mods you've done to suspension look like real hodgepodge. I'm not a fan of putting together shocks and springs from different manufacturers. This step along with adding only rear strengthened sway bar may lead to unpredictable (and dangerous) behavior of this car when pushed to the limit.

 

Looking forward to seeing the results! Especially in connection with TS setup you have.

 

Not sure how you can call using an OEM Bilstein shock from Jaguar a hodgepodge.

I would prefer an OEM spring as well, but they simply can't be found in the US outside of a wrecking yard and that is more a gamble because who knows the condition. The Adamesh set is the smallest change in rates and heights that I could find.

 

I mean you want to be close to stock suspension setup? If yes don't put modified sway bar without calculate each corner weight distribution and mods both to springs and shocks.

There is a set that looks good for XK8/R:

https://www.jaguarforums.com/forum/x...xk8-xkr-85058/

I'm not sure if the business is going well as Deuce canceled some of his post in this topic

 

All depends on how you drive your car, i.e. fitting a stiffer rear sway bar would make the inner wheel lift in a corner more, and with an open diff (or quaife) would cause loss of traction so in effect slowing you down. But that will only happen if you really drive very spirited. For normal driving (or just above) it may indeed as Charles says feel much more composed.

The Ohlin’s setup didn’t work out, some design failures in making the shocks to fit where made, and there was also something with regards to esp/balancing of the car that didn’t work well due to the cats being disabled)

Personally I would also prefer to keep the cats suspension option.

With regards to stiffer springs (not sure if Adamesh are), you may want to consider stiffer shocks as well, that did make a big difference on my car (which also has stiffer lowering springs). This was very noticeable in large speed corners and bumps, it reduces jumping of the stiffer springs amongst others, here is what I have done:
https://www.jaguarforums.com/forum/xk8-xkr-17/new-stiffer-cats-shocks-112799/

 

What I have opted to do is get a new set of CATS R-package shocks from Jaguar, which are (supposedly) a bit stiffer than the normal ones.

I don't have a shock dyno to prove this, but that is what is stated in the literature. Feel says they are somewhat stiffer, but I am also comparing against a set that has 85k miles on them, so not fair at all.

I will keep the old CATS shocks and look into rebuild options as Andre has done in Europe. Bushings are shot, but structurally they are in decent shape. Bilstein themselves do rebuilds in San Diego, so that is the first option to explore.

 

So how is the ground clearance running under the diff?

Did eliminating the pre-axle units cause any drone?

There are some posts out in internet land where a guy built a shock dyno
for about $150. He also goes into revalving his bilsteins and the results.

He used the San Diego facility which he notes can sometimes be slow.
This was right at the time where the head guy had died.

BTW, most of the Adamesh stuff is TUV approved. So no worries
about quality.

 

Measured it to be 4.75" at the lowest point.



No. There is what you might describe as a resonant frequency right around 1500rpm at moderate acceleration. Not a drone exactly, but more noticeable than before if you lean into the throttle a bit. At constant speed it isn't an issue at all, and over the last few days it seems to have toned down a bit. Either the exhaust if getting a bit quieter as it gets some miles or I am just getting used to it.

I'll look for that.

Slow I wouldn't mind so much, since I already have replacements but I called them today and they said that they can't refurbish shocks if they are the crimped style.

Unfortunately ours are the crimped type.



Clearly they can be rebuilt, as Avos has proved, if you find someone who is so inclined, but Bilstein themselves won't do it.

The price given if it were rebuildable was $225. The lower bushing is considered a wear item so is extra cost to replace it, so even if they would do the work, it isn't that great a deal against $400 for an entirely new one.

Good to know, but will need to keep looking for other options.

Good to hear.

 

I just checked my invoice for the shocks, and including vat it was about 200 euros per shock (so about 160 euros for everyone outside the EU).

I had the same resonance/drone at these rpms with the x-pipe exhaust, which was pretty anoying for me as it was a common rpm when not driving on highways, but this was for a 5 speed gearbox.

 

Congrats, there's nothing like saving coin on a DIY project.

 

Here you go:

DIY shock dyno - Honda-Tech

in use, and actual self revalving job:

DIY Bilstein revalve project - Honda-Tech

It looks like the dyno framing can be avoided if you happen to have an engine hoist
around. That leaves just the pressure transducer and ADC to acquire.

 

Called the dyno shop where I've had the others done and they had a couple of project cars on the schedule so couldn't get the pulls done this week.

I'll be in Singapore for a couple of weeks but will get the data in early Feb when I'm back. Should be able to find a comparable day, the other plots have been days during this thing we call winter in Phoenix, i.e. sunny, dry, and 50F.

 

Singapore, a contractor friend of mine says that there's many new opportunities for expansion in that market.
Enjoy your trip and be safe.. Hey can I watch your XKR until you return? I'll work any kinks out for you........ just a thought.

 

I finally got the dyno pulls done with the new exhaust. It's been rather warm in Phoenix, so the days are not really comparable.

The Twin Screw baseline was done almost 1yr ago and yesterday was about 10deg warmer and somewhat lower barometric pressure. Power was about 15hp less than before.

The setup is identical other than the exhaust, but even so, the AFR is somewhat more rich than before. I would attribute this to my using water methanol injection. That system just sprays, and has no knowledge of the air density, so it will give the same fuel, with less air, so a richer mixture.

Best torque is supposed to be around 13.3 AFR so the slightly richer mixture could be contributing to the lower power.



The sound:
In inside the car it sounds great. Nice rumble at idle, not intrusive at cruise and an awesome snarl at WOT.

Standing outside beside the car on a dyno... well you can't even hear the exhaust. I thought about taking a video to get the exhaust sound but there was no point. With the bonnet up, doing the pulls, all you can hear is the scream of the supercharger.

I am not sure there is much to conclude from this exercise. The data is interesting, but not exactly comparable.

The one thing that might be interesting to try is to play with the methanol nozzle size and see how tweaking the AFR slightly up or down affects power.

 

In trying to understand the power difference, I played around with various dyno correction factors to see what they did to the numbers.

This is one single dyno pull with several different correction factors applied. Quite the difference...



These are the commonly accepted correction factors and while there may be a mathematical basis behind all of them, they result in significantly different numbers.

If I were into bench racing, I'd use DIN every time.


My conclusion is two fold:
1) Be skeptical of any numbers found out there on the internet because the environment plays a significant role in the outcome. And when you do find them, look for what the ambient conditions were and what correction was applied.

2) Any change less than about 10-15hp is essentially the same, since day to day weather can affect the measurement that much.

 

3) Stock exhaust system is well designed even for 600 crank hp +; talking about 20-30 hp gains is marketing bullshit :-)