Dirty Diesel Distractions

[Aussie Mike]

A couple of weeks before Christmas the turbo on my Diesel Land Rover Sh!t itself. A bit of a curse really as I didn't need the headache of having to mess with my daily driver.

I probably should have just replaced the turbo with another stock one but I'm incapable of not tweaking something when I pull the spanners out.

So I could have bought a new standard turbo for about $1500 but I decided to spend a little more and get something better. What I bought was a Variable Nozzle Turbo. These are a newer technology turbo that uses a ring of vanes around the exhaust turbine to change the angle the exhaust flow hits the turbine wheel. Rather than use a waste gate to bleed off exhaust pressure and slow the turbine wheel it actively control its speed with the vanes.

The upshot of this is you can have a larger turbo that still flows OK at higher RPM but it can adjust the vanes and spin the turbo up faster at lower RPM. The result is almost no lag and an increase right through the range.

Well I finally finished it today and took it for a drive. The low down pull and lack of lag is surprising.

I've still got to get the max boost set on the Dyno. I think it's over boosting a bit causing the ECU to limit fuel and back it off.

Here's a pic of the finished installation. I've also documented the whole job on a Land Rover forum I belong to if anyone is interested: http://www.aulro.com/afvb/projects-t...o-upgrade.html




Now I can get back to working on the Cobra.

Cheers

[Rob. Smith]

How is it controlled ? Auto i.e- load demand or is there a knob on the dash ?

[Aussie Mike]

VNT turbos are usually controlled by the ECU. They either actuate the vanes via an electric actuator or a vacuum diaphragm and solenoid valve setup.

This setup has been simplified. The bloke I bought the turbo from modifies them and adds a boost diaphragm rather than vacuum. He then just sets the max boost pressure and locks it off. The turbo will spool up to the pre set max boost and just sit there through the rev range.

There was probably a fair bit of experimentation to get the right boost diaphragm to work. Seems to work fine so far. It'll be interesting to get it fine tuned on the Dyno.

Cheers

[Merv and Sharon]

Are there any diesel 'Cobras' out there? I suspect that with V8 diesels available there could be?

Merv

[Rob. Smith]

I had a mate in central queensland that put a 6.5 litre diesel in his f100 and found it just too thirsty. But since then I have seen many modifications and chip retunes that it is a very viable (but unattractive ) option.

[Trevor Legate]

All owners of diesel Cobras to be shot on sight. Sorry, them's the rules.

(and yes I do own a diesel 'tractor-engined thingy' but it aint a Cobra...)

[Aussie Mike]

You could probably do it but I don't reckon it would be a pleasant car to drive. Imagine the black smoke chuffing from the side pipes when you put your boot down.

The problem with most diesels is the weight. They have to run cast Iron blocks to cope with the combustion pressures so they are going to be heavy. Getting one to rev is a problem too as even my wifes little 2.0 diesel Jetta red lines at about 4500 RPM.

That being said, Audi did win Le Mans with a V10 diesel so who knows where diesel technology will go. There has been a huge amount of development on these engines in recent years. A chipped 2.0 VW Turbo Diesel will make 143KW and about 420Nm of torque with no other mods. It'll still meet Euro 4 emissions too.

Cheers

[Merv and Sharon]

Sacrilege? The new CR diesels could be interesting. Certainly cleaner. The one in our new Merc is a great and has huge torque. Not sure if Ford make them however!

Merv

[Gav]

Dirty Diesels Done Dirt Cheap.
Top stuff Mikey.