My Disco 2 TD5 at 3 years old manages about 30 - 31 mpg steady. That's with the EGR blanked off by a wee plate.
Before that it was struggling at about 25 - 26 mpg.

So, not only does the car perform MUCH better with the EGR blanked, but the fuel consumption is about TWENTY PERCENT better too.

That's my contribution to cutting down emisssions.

At my age who cares about global warming anyway? If this good weather is global warming, get those Landies out boys and give us more CO2 !

CharlesY

The thing is, if the egr is making the emissions a bit cleaner, (which I doubt), the improvement is cancelled out by the fact that you have to use up to 20% MORE fuel by leaving it in circuit. The same goes for the cat if you ask me. All the expensive precious metals and you need more fossil fuel. Any greenies here to give an opinion?

Not too bad for an auto

I get between 30/36 mpg outa my td5

i have a 97 300 tdi i get about 30-35 mpg but you need to be abit light on the pedal

I've blanked off my EGR valve and replaced the front exhaust pipe with the non cat landrover pipe. This improves the MPG and response.

Still 26/31 is the best I can get

26 to 31 mpg is not bad for a two-ton 4x4 with the aerodynamics of a brick.

However, no-one should underestimate the potential to better their fuel consumption by perhaps 20% (25 mpg becomes 30 mpg) simply by developing good techniques when driving. Basically, we neeed to learn to drive our Landies like truck-drivers drive trucks. Look WAY ahead, get the speed up to cruising, keep well clear of other traffic, and do pretty much anything to avoid slowing down or using the brakes. Learn to judge coming corners well, slow down on the throttle not the brakes, and drive gently all through the bends on your own side of the line all the way. In a TD5 manual, hit 2,500 rpm in 1st and second, and after that try never to exceed about 2,250 rpm. Get into high gears as soon as possible, and cruise with a fairy foot....

Of course, Slob may have a problem with the Fairy Foot part!

With an Auto your options are fewer. The auto is seldom as good on fuel not because it's an auto, but more because the driver can't quite control it as he can with a manual. The auto won't let you change gears UP as soon as you would like, and most of them don't change up as soon as we might prefer. Generally in an auto if you give it a good squirt through the gears to get up to speed quite quickly then back right off so it changes to it's highest gear, you can cruise from there in lock-up top gear. Find out when (what speed) and why it drops out of lockup top gear and try to drive fast enough to keep it locked-up.

With just a little alteration in the way we drive, we can make a big saving on fuel.

People with ornery engines (200tdi / 300 tdi and NOT TD5s) should get a turbo boost gauge fitted. I have one in my TD5 anyway. Turning the boost pressure up a bit is dead easy, and you can get more miles to a gallon if you can persuade the turbo to stuff in more air while you cruise. With a boost gauge fitted you can see when the waste gate opens, and what the maximum boost is. It's fun to tinker!

I can hardly wait to hear what Slob says about this.

CharlesY

Interested in what you are saying about a boost gauge and altering the boost. No idea how to do it.

Boost gauges are easily available and cheap.

For gasoline engines they are usually rated on the scale from -1 bar through - up to about 2 bar, or in decent Imperial units from -15psi through 0 to about + 30 psi.

For diesels we can use a gauge set to start at ZERO, not minus 1 bar. We never get high vacuum in our inlets. In fact unless our air filters are choked we should never have any minus in our inlets.

Turbos will usually hit about 1 bar boost, say 15 psi, effectively doubling the amount of air going in to the cylinders.

Going up to about 20 psi boost say 1.3 bar is going to help without straining anything. The gauge is fun to observe and dead easy to fit. Gauge kits come with all the required bits.

TD5 turbo pressure is controlled by the engine control unit thing, so turning it up in the usual way isn't going to work. GGGrrrrrrrrr......

CharlesY

OK sow how is the boost pressure adjusted?

I've seen the boost bleed valves on ebay, a small needle valve that you pipe between the waste gate actuator and pipe. These basically bleed off a very small amount of air so more boost is created before the wastegate can open.

I'll have to have a good look under the bonnet andf get my head around it all. I didnt think there was any valves or a wastegate. I thought the inlet went from the turbio through the intercooler and then into the inlet manifold. Any moving parts in there would surely be gummed up with all the orrible black stuff from the EGR?

ALL turbos have waste-gate valves of one kind or the other.
There are two common types.
One looks like a poppet-valve (just like an exhaust valve shape) and the other is more like a flap valve.
Whichever kind it is, it is held SHUT by a spring. This forces all the exhaust from the engine to pass through the turbine making it spin very fast. Many turbos will spin at 200,000 rpm, and small ones even more!

On the end of the spring is a pressure capsule thing that pulls (or PUSHES) the valve OPEN by yanking on a pull-rod attached to the valve. When the valve opens a heap of exhaust by-passes the turbine and the thing backs off quickly.

The idea is that the turbo runs up to high speed as the exhaust gas pressure temperature and velocity increases (i.e. you clogged the GO pedal) and pressure builds up in the inlet tract after the turbo. Because the air pressure goes up, the fuel injection is increased to match, so we now have more air AND more fuel, so the engine makes more power ... and LOTS more exhaust, so the turbo spins a bit faster yet, increases the air pressure even more, the fuel increases, the exhaust increases, and in no time flat (maybe three seconds) the turbo is spinning way out of control and the whole the thing blows up grand style. Somehow it needs to be controlled.

So, the inlet manifold pressure is sent down a wee plastic pipe to the turbo's pressure capsule thing where the pressure fights against the spring holding the valve shut. When the pressure is OTT, the capsule overcomes the spring and starts to open the valve.

The setting of boost pressure is the wee rod between the pressure capsule and the wastegate valve lever. It is a bottle screw arrangement. Making it SHORTER will usually (always?) INCREASE the boost pressure. Trial and error job.

Best NEVER do this unless you have a boost gauge fitted first.

Gently increase boost a little at a time to about 1.3 to 1.5 bar.
If the engine knocks or seems stressed at all, back it off again.

Lunatics (who think they are experts) clamp the capsule pressure pipe with a plastic brake pipe clamp, and let their turbos rip. I suggest none of us do this silly trick ...

I did my SAAB 900 Turbo Aero 16v too much first time and it hit 30 psi boost before the engine shut itself down. I thought it had broken the crank. The performance was incredible. Black rubber marks on the motorway at 70 mph!
155 mph on the flat! But I am a good boy now in a Disco.

CharlesY

Thanks CharlesY thats a great explanation and makes things a lot clearer. I might fit a gauge but probably will leave the settings well alone!

The gauge is fun to watch.
The pressure goes up incredibly quickly.

For about £20 it's a fun dial.

Makes us look like we know something about it!

CharlesY

benn considering this since i got my disco "turning the boost up" but thought i would get a bit of stick for doing it, glad someone is gonna have the balls to do it with me haha.

RAZ8550TDI said:

benn considering this since i got my disco "turning the boost up" but thought i would get a bit of stick for doing it, glad someone is gonna have the balls to do it with me haha.

Click to expand...

If anyone wants to see what happened to a big engine when they ran it at 100 psi boost (no kidding, 7 bar, 100psi) let me know.

Believe me, it BROKE, and they weren't going to fix it ...

If I knew how to do it I would post a small Powerpoint on the forum to let y'all see it.

CharlesY

My Disco II TD5 took 78 litres 16.5 gallons of diesel to brim it today, after 483 miles.
That looks like 29.3 miles per gallon to me. This mileage includes runs into Glasgow (puke ...) stuck in traffic jams, motorways cruising about 65 - 70, and a fair bit of dodging about the private roads around the smallholdings, and some work with a bloody big 4-wheel trailer on the back.

All in all it isn't too bad.

CharlesY

Not bad at all. On my recent run to zummerzet, i cruised at 65-70 which sits at around 2500rpm. I hadnt researched what the best cruising speed was but it felt about right so I just sat there between 2500 - 2700 rpm. Usually I would be doing 80-90 in the RH lane going for it and moaning about people not getting out of the way. Now its mainly LH lane. I did open it up to 80 once or twice to break the monotony but overall it was a very relaxing way to drive.