Lugging is the worst damage and stress you can do on an engine.

Its when your engine is producing barely enough power to meet the demand.
For instance, going uphill at 1200 rpm.
The supercharged xkr can handle it a little better due to good torque at that range.

 

Below is a video that explain the technical side of lugging.
I can explain it in a different way.
If you use your XK to pull a horse trailer with a horse in it, you will destroy it. A Range Rover with the same engine can do it for all its life.


https://www.youtube.com/watch?v=soJe...ature=youtu.be

 

I'm pretty sure an XK can pull a horse trailer with a horse in it! I mean it's a 4.2 V8 with 300hp and enough torque to do the job.
We have an automatic gearbox which would feels what gear is needed to pull the trailer and not lugging the engine.

 

Yes, it could pull the trailer, and you could also manually shift the transmission to maintain a higher engine RPM. However, since the engine cooling system is marginal with the plastic thermostat housing and relatively delicate small hoses, such extended use will likely require you to perform service on the cooling system sooner than you otherwise might. Not to mention the transmission ATF.

 

The transmission is built to cope with 300hk and alot of torque and you can give it full trottle from standstill with all the strain that will do but it can't pull a trailer with a horsy!

I understand that our Renault Clio 0.9l engine will have problems pulling it but a big V8 will have no problem and will not strain the engine or gearbox.

Okay, if you pull a trailer on daily basis and drive it like you drive without a trailer.


We are getting out of topic here!:-)

 

If you'll forgive this, lugging puts a larger strain on the drive train (crank, connecting rods etc.) at low RPM / low oil flow than at higher revs. Higher speed, low load is much easier than low RPM high load running. The reason a comparable diesel engine is so much heavier built is to handle to impact stresses at low RPM.

The other side of the coin is the cam dynamics and ECU tuning isn't real happy down low. They're forced to do it for emissions and CAFE fuel economy ratings but the engine isn't performing well there. Similar for Harley Davidson's sportster motors. They need to rev to run efficient where the big twins don't and will lug easier.

The benefit of the Eaton on the //R is is you gain back the lost volumetric efficiency down low and the engine will lug easier. I've taught mine to up shift when I give it some throttle before 1500 rpm. You just need to lean on it a little until it shifts up and then back off. It'll take a couple cycles before the ECU adapts to your driving style. You could almost say that you haven't trained your car properly. Plus if you are stuck in slow mode all the time, use the paddles and keep the engine closer to 2k. You might lose a little fuel mileage but you'll enjoy the car more.

 

The issue of lugging with the XK engine is irrelevant. The "resonance range" of 1200-1350 is indeed exactly in the range the transmission permits in city driving - which is why the resonance can be such an issue (and the resonance is easily if not cheaply solved by the Jaguar bracket fix). The engine is NOT lugging because the transmission does not permit lugging - there is no possibility of damage caused by lugging - and the 300 hp XK engine has more than enough power (and speed) for any conceivable legal circumstance regardless of what XKR owners would like to think.

 

The 510hp XK absolutely permits lugging if you pussyfoot about with the gas peddle.
Moreover, it often takes off in 2nd gear when it should not and it often shifts in 6th gear below 45mph. Its not a smart transmission, its still relying on the torque convertor and your foot.

I imagine that if it did all this on the regular 285hp, it could really be classified as lugging. Perhaps that car is geared lower, or the shift program is radically different. In some sense it would have to be.

 

Not at all.

First of all, HP has nothing to do with the equation. A farm tractor can pull a tree out of the ground or pull your XK out of a lake, yet most of them are only 40hp.

A lorry only has 350hp and pulls 40,000kg.

Even a Range Rover has to be put in special towing mode, where the engine is prevented from lugging. It also has to have a massive transmission cooler to be able to do that.

 

Transmission tuning is Jaguar's low point across their product line.

Drive a Maserati with same transmission and it's night & day better.

 

I suspect its because they are trying to serve 2 masters, mainly the elderly buyer.
In Sport mode it absolutely will never lug the engine. Which is what I use on very cold starts.

 

Sport mode is OK, but then it keeps the gear excessively long. It's not very natural. On my XE, it's darn near impossible to know what gear I am in if I had to guess. The master Jaguar is serving is the EPA fuel rating... Elderly (or me - youngish strapping lad ;-) ) would be just as happy with 5-6 gears over 8 gears...

 

Its really reassuring to know that someone else feels that way too.

Besides imparting that disingenuous feeling of needlessly remaining in a lower gear, its effectively needless wear. I would have bought a Porsche if I wanted that feel.

 

On 35MPH roads if I'm using cruise control, I will drop one gear from its automatic choice, then move the selector to sport.

This gets rids of the vibration from be the exhaust manifold being out of tune with the flow/velocity if it had stayed at the lower RPM.

As for MPG, I notice no real difference at 35MPH with the above method compared to leaving it in auto. In general, MPG goes to pieces for me at or below 35MPH.

 

I do not know whether this is true of the X150 or not, but a lot of Porsche 911 engine failures 1999-2002 are rooted in not enough oil flow from the oil pump at low RPM. Cars driven at low RPM for sustained periods would have the oil slung out faster than it would be replenished through bearings.

While I do not know if this applies to X150's, I tend to make sure I'm not staying at low RPM for sustained periods.

 

As you are aware, a horizontal engine has the inherent disadvantage of poor lubrication.

 

This was failure of the end bearings. At low RPM there wasn't enough push for flow into some of the tighter areas. Stagnation and eventual starvation would occur.

 

An OEM muffler is a waste of money because it also has the drone!
either use the paddle to change gear OR turn up the radio...........both options are completely free........... that's what I do!

Cheers, Adrian

 

Yes but the drone is so low now that I can hardly hear it!:-)
And as I understood, Jag sells a mount for the Cats to remove the drone with the OEM exhaust.

 

I discussed this with my husband after reading this thread. Mine drones/vibrates at about 1250. Least expensive solution, Downshift.