VNT on a mechanical turbo diesel....

I fully agree and I am having great fun with my Wife's 150 Vectra. Originally the power band was about 1650 rpm to 4000 and now it is about 1800 to 4800 having gone with relatively little effort from 150/236 to 230/335. Part of the fun is blowing Audi Coupes and BMWs into the weeds plus your boy racers who cannot drive anyway.
The 2 litre Subaru power bands above are 2750 to 3000 all the way to 6500, 7000 or even 8000 rpm. Max torque between 4400 and 4800 and max power between 6300 and 7000 rpm.
 
I'm driving an ageing BMW 528i for the time being and it's nowhere nearly as rapid in the midrange as was my remapped Peugeot 406 2.2 HDi.

Given foot to the floor tactics the E39 gives a good account of itself but it's not a fast car, just a comfortable and easy to drive one which gets on with the job at hand.
 
Indeed, this is what I try to explain to people,

Diesels driven in "normal" conditions in a normal every day driving situation will use less fuel than an equivalent petrol and even more so on the motorway,

but you "rag" the nut's off them then they will chew it up like it's going out of fashion.
 
Indeed, this is what I try to explain to people,

Diesels driven in "normal" conditions in a normal every day driving situation will use less fuel than an equivalent petrol and even more so on the motorway,

but you "rag" the nut's off them then they will chew it up like it's going out of fashion.

I've given up with that approach. Some people just won't accept that diesel is a worthwhile proposition now.
 
This is an age old argument now and I guess it won't sink in,

There's nothing wrong with say that you prefer a petrol to a diesel, that's all fine and dandy because people have the preferences but to call petrol superior to diesel is completely wrong, both have there benefits and both have there flaws and both need to be experienced to be appreciated properly.

I love the big midrange stonk of a turbo diesel and the fact that when you're fed up hooning about like an idiot they will become economical and effortless. Plus there are diesels that sound good, the big bassy gruff tone is rather nice :)

I love the fact that you can rev the nuts off of a petrol and that you have to work the gearbox to make good progress in them, NA petrols are my favourite of allover there FI counter parts, much more honest and very linear power delivery and they sound much nicer no turbo hiss or supercharger wine, just pure adrenaline fueled aural pornography...love it

If I were to have a second car then I would get a petrol, just so I could make the choice, the big muscle diesel or the screaming petrol....

Both brilliant in there own right...
 
Yeah I know that, when I said FI I ment forced induction, not fuel injection ;)

Sorry, please do accept my apology.

Diesel engines do lend themselves to forced induction, the main reason being that there is no throttle.

We could also argue that a NA diesel is hopelessly spineless. And we'd be correct and thus we'd win the argument. Which makes forced induction an essential. Let's face it railway diesels have been turbocharged since their inception. Two stroke engines don't resond well to turbocharging as such but mechanical supercharging is still used.
 
No problem mate,

and yes non forced inducted diesel are spineless, my mate had a golf mk4 SDI and it was crap, econmical but that said his new mk5 2.0 tdi 140 does more mpg when driven normaly

I did think about using a supercharger on my car to complement the bigger turbo I've go coming off of ebay
 
We had a Seat Ibiza 1.9d, this was a NA one with the 1896cc 4 cylinder engine, indirect injection and worth about 69-70bhp at best.

It was fine and would pull from idle speed very convincingly. It all went downhill thereon.

Diminishing torque delivery by 2000rpm. Dead in the water by 3000rpm.
 
The Vauxhall/Opel/SAAB/Alpha/Fiat 1.9 engine actually has 8 runners in the inlet manifold and four of these, one for each cylinder, have a swirl flap. The inlet manifold itself has a single butterfly throttle body. The purpose of this is probably to allow the engine to develop vacum at stages to operate gas recycling and comply with emmission regulations.

I posted photos up somewhere, showing the innards of the inlet manifold which conveniently is in two halves.
 
Fair enough,

I would say then that if you're running a bigger turbo and flowing more air you may require some kind of recirculating valve or dump valve in your intake pipe work to preserve your turbo.
 
This is not a problem I anticipate and there is no turbo stall at present. If it were to raise its head and become an issue with the bigger cover and wheel, it is easy to deal with.
 
Some multivalve diesels do use such butterfly valves to enhance low end torque. But diesel engine torque delivery is ultimately governed by fuel delivery only. The accelerator pedal does not directly control airflow into the engine.
 
The solution is simply to put on a BOV in proximity to the throttle body just before the inlet manifold. The 4 flaps referred to above are closed at low RPM to give torque as above and open gradually to wide open depending on throttle position and engine load. Having super glued these flaps open on the old manifold before it was replaced I could not feel any difference in operation between them operating and them being wide open.
As an experiment I intend to remove the butterfly from the throttle body to see what the effect might be.
 
Update:
As I have a spare inlet manifold for the Vauxhall 150 engine I have now removed the throttle flaps and need to plug the holes before porting the manifold where I plug it and make light porting alterations on the manifold generally which appears very well designed.
Yesterday I completed the following :
1. An improved feed from the modified air scoop in front of the front mount intercooler to the air box.
2. An improved feed from the MAF sensor body at 70mm dropping to 60mm and down to the compressor cover entry at 57mm.
3. An improved feed from the compressor outlet to the hot side of the intercooler.
I will make a further improvement to this in advance of fitting the turbo with the 56 cover and 60 wheel.
4. I removed the oil breather from the top of the engine that runs to the inlet tract. This now vents to a plastic container with some vents in the top acting as a catch can. I am interested to see what if anything gathers in this container.
5. I removed the butterfly flap from the throttle body but left the spindle in place until I determine what the effects might be. The spindle can be removed at a later stage.

I have probably only done 10 miles with no negative feedback and it will take a trip to the rolling road to determine what gains have been achieved. I would guess the air is flowing better so with a bit more fuel there will be more power.
I am also now looking at water methanol injection both to improve fuel economy and top end power. I already use water methanol injection on one of my Subaru engines, however, diesel operation has a different philisophy.
 
Sounds good,

I've been looking into water/methanol injection as well, I've been looking at kits from DevilsOwn as I've heard good things about them.
From what I can work out on diesels the set up is pretty similar,

What is the philosophy have you found? I'd be interested in reading your finds :)
 
My experience on a petrol is that the water methanol kit greatly reduces EGTs so it adds safety. It did not add a lot of bhp, perhaps 12 bhp around 400 bhp (the 2 litre turbo charged engineis now 422 bhp), however, the big advantage was that with the reduced EGTs and use of water methanol I was able to make good additions of ignition advance which resulted in noticably more torque and that is obviously the most outstanding gain with my petrol experience.
On the diesel I expect there will be EGT reductions but until I fit an EGT guage I don't know what these are at present and I expect that the water methanol will lead to cleaner burning of the fuel already there but it should be possible to increase fuelling over the present settings and it may help clean the engine up if it were smokey which this engine is not at present.
Depending how the kit is set up I think there will also be gains in fuel economy when the car is being driven normally.
The previous kit came from Snow and I am in touch with their Technical Department to get as much information as possible.
This is what I expect will happen and it will be another interesting voyage of discovery.
 
I would go for Snow Performance myself but I do find there products rather expensive, yes they are very high tech but I really don't need that level of control
 

Similar threads


Please watch this on my YouTube channel & Subscribe.


Back
Top