VNT on a mechanical turbo diesel....

[jarrus]

I found this while browsing the net and it made for a very interesting read,
http://www.vwdiesel.net/forum/index.php?topic=10365.0

and obviously I thought about doing something like this myself, but I still having got my head around how it all works together,

anyone care to interpret it so I understand it all?
the trouble I have is that if I was there and looked under the bonnet of the car I would have no trouble in understanding how it worked because I could physically see it, but it doesn't have to be working though for me to understand it.

Thanks for the help

Brett

[jarrus]

Ps I know it's from another forum but there is no where else I can find this kind of information,

[Yugguy]

http://www.myturbodiesel.com/1000q/a...ate-adjust.htm

basically a VNT is just a rod that varies the boost that the turbo provides by changing the angle of the vanes - the idea being that when you're cruising you dont need much boost, so by lowering the boost in this way you save fuel and increase turbo life.

All PD VAG engines have one, like mine, yours may already have one. I'd have thought it would have some way of varying boost.

[jarrus]

Thanks for the reply, my car doesn't have a vnt, I know how they work but I'm not sure how this guys system works to make it work on a diesel engine without an ecu,
I have an idea but it's not the best way from I can gather,

[jarrus]

Thanks for the link, i didn't say it before, it was actually more insightful than I thought it would be, from what I can gather, the actuator is move by vacuum pressure, where would this vacuum pressure come from to change the vanes angle of attack? Could you use an electronic boost controller like an apexi one to control the actuator correctly?

[jarrus]

Now, I have read the posts properly, and from what I can tell, he is using the position of the throttle to control the vanes on the turbo, seems like a quite affective and simple way of doing it, any thoughts?

[Yugguy]

Originally Posted by jarrus

Thanks for the link, i didn't say it before, it was actually more insightful than I thought it would be, from what I can gather, the actuator is move by vacuum pressure, where would this vacuum pressure come from to change the vanes angle of attack? Could you use an electronic boost controller like an apexi one to control the actuator correctly?

The vacuum pressure is controlled by the ECU according to demand on the engine, so either when needing to accelerate or go up a hill. Not a turbo expert so can't answer your question. Doesn't your car have any kind of ECU, it must have something, shurley?

[jarrus]

No, none at all

My engine is the 1.9 turbo diesel (XUD9T) rather than the later HDi engine in (DW10)
and from what I have learnt is that the hdi 90 fitted to the 306 doesn't have a VNT ethier so I'm limited there, I would let this lie and just buy a "normal" bigger turbo but people have fitted VNT's to there 300D mercs with out an ecu and still used it's benefits,
the appeal to me is not the potential to make more power (i reckon i could make as much power on a non vnt) but the fact that I can access that power/torque more easily which should make driving at normal speeds more enjoyable, I mean yes people have told me to buy an engine that can use it but or a different car, but I like what I have and I wish to improve it,

[HDi fun]

It's not so much as controlling boost in steady state (ie. fixed speed driving) that VNTs or VGTs are used. At a steady 110mph the car will provide constant turbo pressure anway, for example.

The variable geometry is there to alleviate the age old problem of lag so that the turbocharger does less to impede exhaust gas flow at very low revs yet spools up more rapidly when you command more torque with your right foot.

I sometimes struggle with the 'boost' word. Seems to mis-represent the reason for supercharging cars.

[jarrus]

Indeed, that's why I'm looking into doing it,

I do think when talking about turbocharging that boost does sound like a chavy word even though it's a correct word

[jarrus]

Right I think I have figured out what i've got to do now and it's far more simple than I thought,

I'll post a link of a video which explains it all...

[pgarner]

go for it ?would like to see how you set up the VNT

[jarrus]

I've found the video now and it is really quite simple,

here it is,
http://www.youtube.com/watch?v=Frs6aQGOrlo
and this one will help explain it some more
http://www.youtube.com/watch?v=XIKVn...eature=related

[pgarner]

so its fitted to the throotle then?

[jarrus]

Yes it is, it still has an actuator which will reduce the pressure when the turbine is flowing the correct amount of air,

but i think i would have to use an actuator from a normal waste gated turbo for it to operate properly, the one on VNT see vacuum rather than pressure

It's been done before on other cars than a 306 and i see no reason why it shouldn't work on my car, and it should make for a very drivable car as well as being quick

[jarrus]

http://www.thedodgegarage.com/turbo_vnt.html

I found that while surfing the net and that should help loads in my quest for a drive able car

[jarrus]

Right then, need to clear something up some more,

DO electronic boost controllers use throttle position as an input as well as engine rpms?

[HDi fun]

They use eveything; pedal position, rpm, air temp/density, mass airflow, coolant temp, road speed and possibly some more parameters besides.

You'd probably be better off replacing the car with an HDi model, fiting an intercooler and then remapping to about 150bhp.

Unless, of course, the objective is to produce the worlds quickest XUD-T whereupon we're all going to have to do some serious thinking.

[jarrus]

Pretty much that is the objective, but there is a guy recently had 213 hp from his xud-t without the aid of lpg or nos or water meths but the thing that concerns me the most is that it only produced 245 lbft torque while producing that power, I guess the fact that it's an IDI engine is a limiting factor, However, I have seen recently as well someone make a "mHDI" where by taking all the common rail injection system off which is very problematic on early hdi's and it has been replace by a bosch ve pump and injectors

*Click image to view video*

benefits of this is the fact that it will be more reliable, more power than a xud and the ability to run SVO, WVO or bio diesel more easily

[HDi fun]

The numbers stack up quite neatly - this equate to about 4500rpm. I am slightly concerned about your reliability statement. The HDi engines are actually very durable anyway, they're not known for failing.

Secondly, I don't think that taking an XUD-T and winding 200+ bhp from it is going to be more reliable than a standard HDi motor.

Just a thought.

I know I have said on many occasions that the runing costs of modern diesels do escalate I don't mean that they're not reliable. Just that the routine maintenance is pricey.

[jarrus]

Yes I know what you ment, they can be unreliable, like I said it was the early ones that had the problems, not the dw12's the dw10's found in the 306 and 406 and 206 had injector system issues,

the blocks are quite strong though

But seriously though 213 hp @4800 rpm and 245 ft/lb torque really isn't figures I would want, I may as well get a turbo petrol, with that hp it should have more like 345 lbft, now that's worth doing,

I just think that the possibility are slowly diminishing, and maybe either a 2.2 hdi or a gti6 turbo is the way to go.... but I am still intrigued by the mHDI project, it really seems a fairly simple concept

[HDi fun]

Originally Posted by jarrus

Yes I know what you ment, they can be unreliable, like I said it was the early ones that had the problems, not the dw12's the dw10's found in the 306 and 406 and 206 had injector system issues,

the blocks are quite strong though

But seriously though 213 hp @4800 rpm and 245 ft/lb torque really isn't figures I would want, I may as well get a turbo petrol, with that hp it should have more like 345 lbft, now that's worth doing,

I just think that the possibility are slowly diminishing, and maybe either a 2.2 hdi or a gti6 turbo is the way to go.... but I am still intrigued by the mHDI project, it really seems a fairly simple concept

I don't think you'll get 345lbft from a petrol turbo of only 2 litres. Power is only a function of torque and revs. 300bhp is perfectly possible but it'll be a revvy beast (which is something small petrol engines do very well).

The 2.2 HDi is very tunable but if you could get hold of the 2.2 which went in the 05-07 Mondeo TDCi you'll be starting with about 155bhp. It's a better engine in my opinion. Not quite a silky as the DW12TED4 but even less laggy.

[jarrus]

Yeah I know, 345lbft would be hard to get out of a 2.0 petrol but no impossible,

I got a quote from pug1off a while ago for a 2.2 hdi conversion and they quoted me £3500 plus vat for fitting of the engine and gearbox with a new clutch and new belts,

but I think I might give the mHDi a go before I admit defeat

[HDi fun]

Pug1Off will do a superb job for you though.

Does the £3500 include the cost of the engine itself?

[jarrus]

Yes it does. Have you had dealings with them before then, Paul?