Twin Turbo Diesel Setup, what's best???

[Patrolling Paddy]

Spotted the 1HD-TT thread in the Toyota section and it got me thinking again about setting up mine with two.

There seems to be some discussion about what is the best setup, alot of the input seems to be coming from the car racing scene. All the info sounds good and each setup seems to have it's pros and cons.

Does anyone have diesel specific info about twin turbo's?

Now I am talking 6 cylinder not V8's.

Is it best to run two so that a smaller one spools up quick and feeds the bigger one to continue the power up through the revs, given that most 6 cyl diesels will top out about 4500rpm.
OR
Two equal size turbo's running off 3 cyl each?

I am thinking that 2 turbo's off one common exhaust manifold would not achieve a great deal because there wouldn't be enough exhaust flow to spool them both up quick enough, is this right?

What about tuning how do you balance them so that they are both equal boost etc...

Would the intake be better off going to a common manifold or 2 3cyl manifold, I am thinking one common manifold.

So many questions I can't even think of them all right now.

Please help

PP

[RODEONICK]

i think i might try that on my dao if i don't sell my spare turbo.
I think your on the right track though. i think that you want common manifold for both turbos on both the inlet and exhaust sides. balancing won't be an issue than as the pressure will be the same on both.

I like the idea of staged turbos just unsure of how to safely set it up.
keep us posted please
Cheers Nick

[BIGDAVET86]

Not diesle specific but surely two differnt turbos would be best. One small one that is boosting off idle and one that can kick in at say 2500rpm and kick all the way to redline. If you went for two of the same they would need to be pretty small otherwise i would think that they woulnt have enough puff.

I would think that you would deffinately need a single manifold for the intake, no matter which route you take, so that the presures are equalised. The exhaust side would be a tricky one, if you went for two of the same turbos, then perhaps it would be easier to make two 3 cyl manifolds.

either way its a awesome idea and i deffinately reckon you should do it PP, c-mon spend some of those $$$.

Cheers
Dave

[fullmetaljacket]

very interesting......there would be issues with both twin single systems and a twin seperate systems....just throwing around some ideas as I havent had experance with either

twin single (piggy back) system, your spool up wouldent hit the correct rpm untill high in the range unless you mated a 2ltr turbo to a 4ltr for example and fitted it to a 4ltr+ engine, but then why not fit a matched 4ltr turbo in the first place

if you did a twin seperate system on the exhaust side it would be best to have a common intake manifold to reduce turbo flutter, and link the wastegate signal lines so one turbo isn't working harder or easier than the other. The turbo's would have to be a matched pair, and the pair together would have to be matched to the engine's available flow rates.....way way too much maths for me, but shurly there must be a calculating program out there.

I say do it:thumb:.......this looks badarse!

http://www.davesdiesel.com/Twin_Turbos_2.jpg

[bainsybainsy]

paddy, iv doen all the hard work for u! (i started the 1HD-TT thread) the best 6cyl twin turbo diesel setup is parallel VGT (variable geometry turbo) from 2 banks of 3 pipes and joining the 2 compressor outlets to share the one manifold. the VGT turbo in itself is just like the compounding turbo setup but in 1 single turbo. it spools fast from the veins in the compressor bein small, acting like a small impellor, then, as the RPM rises it opens the veins and makes big boost.

its like running twin compounding but with just 2 turbos! not 4! (4 would be a sight to see!)VGT's are commonly seen on the iveco and cummins motors.

the only downside is the price and some are electronically controlled but can be modified to work from boost pressure. ill be running the setup on my 4.4L 1HD diesel

hope i was of some help!

[Z()LTAN]

paddy unfortunately a twin turbo setup on your Td42 just wont be worth it.

If you have a small turbo feeding a larger its only going to get as much boost as the first smaller one allows.

The larger turbo is going to have to suck through the first (which is a fairly large restriction), this is going to cause the smaller one to spin past its RPM limit, hit terminal velocity and destroy itself.

Twin turbo setups are for large boost over a wide range. Now your not going to want to run any more than 30-35 psi in your engine (so long as you can keep your egt's down) A garret t3 high flowed is more than capable of giving that boost pressure. The TD42 can handle almost 40 psi without the head wanting to lift off, its only the heat that kills them. Custom water air inter cooling, variable rate water meth injection are a minimum to lower temps.

You would be much better off getting a vortech supercharger and using that in conjunction with a Garret t3/t4 hybrid turbo.

Modify the supercharger pulley setup with an electric clutch (like an air con) so you can cut it off after 1200-1500 rpm, by which stage the turbo has enough exhaust gas flow to have spooled up nicely.

You can modify a air con idle up circuit to deal with the cut in and cut out of the supercharger, instead of having the sensor pickup pressure when it was in the air con circuit have it pick up rpm from the tacho sensor.

its all a fair bit easier than it sounds.

Ps. Remember with all the extra boost your going to need more fuel to get the right psychlrometric (spelling?) ratio for combustion, extensive pump upgrades with boost compensation and higher flow fuel rails are going to be necessary.

You are going to be looking at $30k atleast to get it to a power gaining position...

Do it by all meens and dont let anyone tell you its not possible, coz anything is possible with enough money.

[bainsybainsy]

another thing i want to add, my engine is set up for running bigger boost pressures. my fuel pump can suppily more fuel an my head and internals are alot stronger. i wouldnt just go and feed lots of boost into a stock motor. its a good recipe for disaster.

iv spent the past 2 weeks reading every performance forum on the web, goin to librarys, goin to performance shops, asking people in the know. gettin heaps of information. plus being a diesel mechanic has helped alot aswell.

once ur motor is setup good, the twin VGT setup would be the go. its got the spooling of a compounding turbo system and the effictiveness of a parallel system. i didnt go round getting all this info for nothing...

[Patrolling Paddy]

All the info is great guys and I do realise that money is going to be involved.
1 thing about all this though that I still haven't grasped 100%, isn't the purpose of the turbo to supply more air volume to the engine? To get the volume you need to have boost but, with twin turbos you can increase the volume x2 (allow for efficiency etc...) but not have to run the extra boost.
Or does having twins not work out like that?

I have been looking to reco the engine anyway just cause but I would like to have a plan in place before I touch anything so I only have to do it once.

bainsybainsy what books have you been reasearching? Most stuff I have seen (not looked real hard yet) has been to do with standard basic principles and doesn't go into what happens with mods or the effects they have.
VGT's would be fine I'm sure but I am a bit of a dinosaur in thinking and I am worried about reliability of some of this fancy stuff, if it can be mechanically controlled I would be a lot happier about it (that's most everything)

Before anyone suggests it I am a diesel man and a petrol V8 conversion is not going to be considered (that's what my street car is for). A V8 diesel conversion of the chev variety doesn't have a huge apeal to me either as they are heavy and don't really make a huge difference over what I have. The new V8 Toyota diesel could be a good thing but there is no way known to man that I will put a Toyota motor in my Nissan, sorry but no.

Can someone please explain the terminologies fo me.
Compound (2 exh manifolds feed 2 turbo's into 1 intake manifold??)
Sequential (1 exh manifold and a small turbo feeds a second bigger turbo on both exh and inlet side to bring boost early and carry it through??)
Is there another?

Cheers

PP

[fullmetaljacket]

Compound (2 exh manifolds feed 2 turbo's into 1 intake manifold??)
Sequential (1 exh manifold and a small turbo feeds a second bigger turbo on both exh and inlet side to bring boost early and carry it through??)
Is there another?


parallel is 2 exh manifods ect

compound is a series setup

Restoring the layer structure... (http://www.atsdiesel.com/ATSWebsite/HIWCompounds.asp)

[bainsybainsy]

bainsybainsy what books have you been reasearching? Most stuff I have seen (not looked real hard yet) has been to do with standard basic principles and doesn't go into what happens with mods or the effects they have.

Can someone please explain the terminologies fo me.
Compound (2 exh manifolds feed 2 turbo's into 1 intake manifold??)
Sequential (1 exh manifold and a small turbo feeds a second bigger turbo on both exh and inlet side to bring boost early and carry it through??)
Is there another?

Cheers

PP

just been reading diesel power from usa, its dedicated to performance diesels!

compound and sequential are both the same. its when the exhaust gasses exit the manifold, enter into one turbine, then exit the first turbine and enter the second turbine. like a series electrical circuit. the first and second turbine's have different size compressors, one larger then the other. the same flow applies for the compresors but in the oposite direction. flow starts at the induction, enters the first compressor, which spools up very fast from being a small size. the air then exits the first compressor then enters the second compressor, which is larger. as the engine rpm rises, the exhause gasses flow more and the larger turbine can start turning the larger compressor, producing large boost pressures. the smaller compressor assists this. makin it a quick spooling, high boost setup.

parallel uses 2 exhaust manifolds, each manifold for each turbo. and has 1 common inlet manifold. this setup it better for slow spool but high boost pressures, although twin turbos will spool a little quicker.

here is a bit of an mockup equation!...

working 1:
large turbo = (slow spool + high boost) therefore~
slow spool + high boost /2 = parallel twin turbo (which will spool a fraction quicker)

working 2:
1+1 sequential = (quick spool + medium boost) therefore~
quick spool + medium boost /2 = 1 VGT turbo

therefore:
parallel twin turbo X VGT = parallel twin VGT
parallel twin VGT = (quick spool + hight boost)
quick spool + high boost = bloody awesome :thumb:

hope that all makes sence. i bet iv confused you

[Patrolling Paddy]

working 1:
large turbo = (slow spool + high boost) therefore~
slow spool + high boost /2 = parallel twin turbo (which will spool a fraction quicker)

working 2:
1+1 sequential = (quick spool + medium boost) therefore~
quick spool + medium boost /2 = 1 VGT turbo

therefore:
parallel twin turbo X VGT = parallel twin VGT
parallel twin VGT = (quick spool + hight boost)
quick spool + high boost = bloody awesome :thumb:

hope that all makes sence. i bet iv confused you

Confused somewhat milk comes from cows, dogs go woof.


When you refer to low/medium and high boost what sort od PSI are you meaning?

These VGT turbo's are std equipment on some gear but do you or anyone else know what runs then and where we might find them? Are they available as an aftermarket unit with manual control?

I already have two turbo's that are identical and was thinking that using them in parallel would allow for them to spool up faster then one and hold/maintain the boost for longer given that they will be producing more air volume at less pressure. Is this right or am I on the wrong track?

PP

[BEU77Y]

Why do parrallel setups spool quicker? Isn't each turbo only get half the exhaust? Or is it that smaller turbos(read quick spooling) used for these set ups?

A work mate has a Torana that he drag races.
202 6 cyl Twin Turbo.
The reason he has run 2 turbos is space but he said given the chance he'd just run 1 big one.
He said very hard to set up....
Saying that he is getting 500hp at the wheels and pulling 10s quarters!

[Z()LTAN]

they will be producing more air volume at less pressure. Is this right or am I on the wrong track?

Your not quite on the right track there paddy.

When you bolt a turbo to an engine you are trying to force more air into each cylinder. This extra air can only go into the same cylinder volume as before.

More air same volume?
Pressure is caused by a restriction to flow, in this case the restriction is the piston crown. Therefore the more air flow you create (1,2,3 turbos) the more Pressure you are going to make.

"Flow" is only increased in the non pressurized side of the system. Mind you, if the engine were to create enough exhaust gas to spin up 2 turbos as fast as it does one (not physically possible) it would create a larger flow into the intake manifold and cause boost to rise faster... - This being the guts of your original question.

As BEU77Y said, if you were to put two turbos on in parallel, you would find it would spool slower than with one, as you are splitting the exhaust gases and only getting 1/2 the rotational effort on each exhaust compressor wheel.

Clear as mud?

[dakar61]

paddy unfortunately a twin turbo setup on your Td42 just wont be worth it.

If you have a small turbo feeding a larger its only going to get as much boost as the first smaller one allows.

The larger turbo is going to have to suck through the first (which is a fairly large restriction), this is going to cause the smaller one to spin past its RPM limit, hit terminal velocity and destroy itself.

Aint necessarily so...

A correctly built and matched sequential turbo set-up has intake and exhaust gates to isolate the turbos. When the larger turbo is required the exhaust and inlet gates to are opened and it is fed and driven on its own supply from the engine. Of course the intake and exhaust pressures will be increased due to the work done by the primary turbo. Overboosting or overspeeding of the primary turbo is not an issue because it will be wastegate controlled anyway.

Wow factor would be pretty high with a sequential system on a Patrol or Toyota, no doubt about that.

IMO tho, in a modded engine application, with the fuel supply to support it, a single large turbo is actually a more efficient pump for making air to support big power.

Lag is usually not a problem if its correctly matched and the engine is getting plenty of fuel....

[mud rover]

supercharge it .

[mud rover]

twin surerchargers off toyota 1gg-zue

[bainsybainsy]

1 big one would be better for drag racing, but ur not going to drage race ur patrol are you? the reason for this is they turbo is spooled at the startline, so no need for quick spool. just big boost.

the twin turbo setup spools up quicker because ur splitting the manifolds into 2. each manifold will have the same exhaust pressure but half the flow. so u half the turbine size (smaller turbo) and it would be like increasing the pressure.

superchargers are only good on high hourse power motors because it actually use up engine power to turn the supercharger. they will make a horsepower increase tghough! Turbos use the wasted energy from the exhaust and convert it back to engine power.

[dakar61]

1 big one would be better for drag racing, but ur not going to drage race ur patrol are you? the reason for this is they turbo is spooled at the startline, so no need for quick spool. just big boost.

the twin turbo setup spools up quicker because ur splitting the manifolds into 2. each manifold will have the same exhaust pressure but half the flow. so u half the turbine size (smaller turbo) and it would be like increasing the pressure.

Not talking about drag racing here mate. Bigger single turbos work more efficiently, when set up correctly in a performance diesel application. Talking from experience.

If you have the same exhaust pressure and then halve the turbine size you will overspeed/overheat the turbo and reduce its compressor efficiency. The turbo will then be an expensive exhaust restriction.

If you need two turbos then sequential would be the better way to go...

[mud rover]

superchargers are only good on high hourse power motors because it actually use up engine power to turn the supercharger. they will make a horsepower increase tghough! Turbos use the wasted energy from the exhaust and convert it back to engine power.

superchargers may need power to operate but as u said they also increase horsepower . i don't think that he is wanting to turn his diesel into a drag racer .

supercharging also produces boost from idle up to maximum revs unlike many turbo setups . plus there is generally less external modifacations to the motor and engine bay (ie- less piping).

[Z()LTAN]

+1 for a Super/Turbo setup

[bainsybainsy]

some of the old GM 2 strokes were supercharged and turbo'd. but the only reason for the supercharger was to push the exhaust gasses out. i believe the paralled twin VGT would be best for me, but yeah a super/tubo setup woud be good aswell. all depends on personal preferance and what your going to do with it. either way it will be great!

well im goin away to melbourne for tafe, going to do some more turbo study:crazy:

[Z()LTAN]

bainsy they were actually reffered to as "Blowers" they need the assistance of the blower to enable the scavanging effect as in a 2 stroke there is not any total intake/exhaust stroke.

[stu050]

some of the old GM 2 strokes were supercharged and turbo'd. but the only reason for the supercharger was to push the exhaust gasses out. i believe the paralled twin VGT would be best for me, but yeah a super/tubo setup woud be good aswell. all depends on personal preferance and what your going to do with it. either way it will be great!

well im goin away to melbourne for tafe, going to do some more turbo study:crazy:

The GM 2 stroke diesels had a blower strapped to them, yes, but it was just that, a blower. It did not make any boost, and the tolerances were pretty loose. The engine would not run without it.

Series 71 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Series_71)
A lot of work has to be done to convert say a GM 6/71 blower into somthing that would be suitable to use on a petrol engine, most of it is tightening up the tolerances, and converting it into a compressor. The shafts need to be strengthened, and different bearings are used in the endplates as well.

For research purposes, the Merlin aircraft engine as used during WW2, used a two stage centrifugal supercharger to make bulk horsepower. The Merlin was a V12 of 27L displacement.

Rolls-Royce Merlin - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Rolls-Royce_Merlin)

[bainsybainsy]

ok, i know what a blower is and know what a blower does, but if i called it a blower, some of the non mechanically minded people wouldnt know what im talking about? its "pretty much" exactly the same internals as a supercharger anyway. even a mate of mine whos running a 1500hp blown methanol engine calls it a blower, shouldnt he be calling it a supercharger? he build engines as a part time profession. as i siad, it was used to push exhaust gasses out, not for boost. sorry anyhow.im only an apprentice! so i might not have the best terminologies!

anyways im off to scania then heading to tafe. c yas in 2 weeks!
good luck with whatever you choose paddy!

[turbogu]

compound twins must be the way to go if every cummins powered dodge owner in the states runs a compound set up, even alot of blokes with power strokes and durmax's are starting to go compound twins now days

search dirtymax on you tube, compound twin duramax drag car - very fast

And this is what you get when you throw 100+ k into a powerstroke with hand built everything including a v8 mack mechanical pump conversion!!

http://inlinethumb43.webshots.com/42986/2597454400089319918S200x200Q85.jpg (http://good-times.webshots.com/photo/2597454400089319918AVXrpW)

compound twins is definatley the way to go if set up right

[turbogu]

heres a vid of some pulling truck, most are compounded twin cummins in dodges but the very first truck on the vid is the big bad power stroke

http://thumbs.vidiac.com/9dfd0e7a-a1d2-46db-9181-982a0085f023.jpg (http://video.thedieselgarage.com/video/9dfd0e7a-a1d2-46db-9181-982a0085f023.htm)Click here to see Video (http://video.thedieselgarage.com/video/9dfd0e7a-a1d2-46db-9181-982a0085f023.htm)

" must have sound, 100+ psi boost sounds unreal!!!!

[ol blu 40]

The engine would not run without it.

Well, yes and no... I've seen GM 6v53's run with a broken quill shaft (drives the blower) but when you shut it down you can't start 'em again!

Bower 'slightly' pressurises the airbox allowing positive chamber filling once the inlet ports are exposed...

Cheers, Matt

[ol blu 40]

VGT's are commonly seen on the iveco and cummins motors.

And GU Patrols running the ZD30...

Cheers, Matt

[Patrolling Paddy]

I found one site that had 'true twin turbo' setup and it refered to two identical turbo's plumbed to a common exh manifold and then to a common intake manifold, but it had all array of valves in place to have one turbo at idle up to a set rpm when it then allowes the second to open and recieve suitable exh pressure/flow and supplies extra boost.

I have also seen reference to when the turbo spools. ie it spools up at 1800rpm. Now I can drive mine in a manner that will allow about 2000rpm and as little as 1psi or I can drive it to get 14psi at 1400rpm so what is this reference to spooled and under what conditions is it measured??

PP

[ol blu 40]

"Spooling up" is simply when the turbo actually charges... Your 2000rpm and 1psi I'm guessing is with very little engine load, coz if you hit a hill for example doing 1400rpm you naturally accellerate a little to keep the revs the same. More throttle = more fuel being injected, higher exhaust temps result and there's your boost: expanding exhaust gases exiting!

So you can be on or off boost at practically any revs, more dependant on engine load instead of engine revs.

Cheers, Matt

[Patrolling Paddy]

I understand the more load, more throttle, more boost bit but was just unsure as to the term 'spooled'.
Yeah 2000rpm with 1psi is very light driving or holding a gear rather than changing up with little load, and 14psi at 1400rpm is climbing a hill under full load.

So would the term spooled mean the lowest revs that max boost can be obtained?

If this is the case then this means that my turbo is spooled at 1400rpm under full load correct? When I had the dyno done last week it reached max boost in 4th gear at about 55km/hr which I think works out to about 1400 as well.

Cheers

PP

[ol blu 40]

So would the term spooled mean the lowest revs that max boost can be obtained?PP

I gotta admit that I don't have an answer for that one. Sorry...

Cheers, Matt

[DJR96]

Spooled up really just means the turbo is spinning fast enough to pump enough air to provide useable positive boost pressure at the inlet manifold.

[Sorry this got a bit long.....]

So if you're just dawdling along, the turbo is spinning relatively slow, not creating much boost pressure. Then you stomp the loud pedal, more fuel in, more heat, more exhaust volume out, spins turbo faster (spooling it up), which then creates more boost pressure. There is a delay between you hitting the pedal and the turbo reacting to it, called turbo lag funnily enough. This delay is most prevalent at lower revs because there is less gass flow and the turbo has to speed up from slower revs. At higher revs the turbo is spinning faster even though it may not be creating much boost, so it doesn't have to increase as many rpm's before creating boost, so less lag.

The bigger the turbo, the heavier it's rotating mass and therefore the longer it's lag. And vice-versa for a small turbo.
Have a listen to most of those sled pulling trucks in the video link above. They wind them up gradually, then when they floor it, you suddenly see the black exhaust increase heaps, but there is still a second or two before you hear the turbo really whistling. They've got such big turbo's that even though they're already spooled up a bit, there's still quite a delay before full boost (the whistling) is reached. Oh, and if they are running two sequencially, it is to further increase boost beyond what any one turbo can do by itself. 100psi boost! Scary.:eek: Not that that matters for them, they just want max hp. But it would be very unresponsive for everyday use. A real PITA on the street.

Two smaller turbo's generally will spool up quicker than one big turbo for a given engine size and hp target. Which is why Nissan GTR's and Toyota Supra's run twins. The drag racing scene using those cars often replace them with one large one that will outflow and produce more hp than the little twins. But, they aren't as responsive.


Variable Geometry Turbo's overcome this problem by restricting the exhaust into the turbine housing with a set of vanes. This restriction increases the gas velocity through the vanes and into the turbine wheel. Effectively making it spin much faster than it should for the volume of gas going through it. Thus keeping the turbo's revs up and reducing the lag time to really create boost. Then as the exhaust volume increases, the vanes open up to remove that restriction and prevent the turbo from over revving to destruction. (So it's pretty important that they work correctly!) Here's a link for the Ford 6.0 VGT that explains with pics:- Page 36: Air Management System (http://dan.prxy.org/Truck/6L_bible_html/html/Page_036.html)

Horsepower is largely limited by the sizing of the turbo system. Providing everything else is up to it's pace. The greater the airflow that can be put through the whole engine and turbo setup, the greater the horsepower. But us 4WD'ers and any daily driven rig need performance from well below the maximum potential. So hence the need for wastegates, VGT's or twin turbo's.

Personally, I think one good VGT is the go. Less plumbing than any twin setup. And much larger flow potential than a wastegated turbo because all of the exhaust gas is being used all of the time. A bigger turbo to start with, yet still capable of providing boost at lower revs.

Another thing is that the more air is compressed (boost pressure) the hotter it will get in the process. Any forced induction of more than a few pounds should be intercooled somehow. Not so much for the performance increase, but for reliabilty/longetivity. Everything else is going to get hotter. Oil will only do it's job up to a certain temperature limit. And no piston is going to survive long with inlet air that could be well over 150 degrees.

Hope this helps explain a few things for you.;)


Trouble for you is, I don't know off hand, of any VGT that would suit engines of around the 4 to 4.5 litre. Most are for the smaller 2.5 and 3 litre engines or for 6 litres and bigger.

[Patrolling Paddy]

Trouble for you is, I don't know off hand, of any VGT that would suit engines of around the 4 to 4.5 litre. Most are for the smaller 2.5 and 3 litre engines or for 6 litres and bigger.


Then twin VGT's to suit a 3 litre should be able to do it? Or maybe a single off a 6 litre?

If the VGT's aren't wastegated then how is the boost set? Do the vanes act as the wastegate at a set pressure?

If a 6 litre unit was fitted to a 4.2 and set to say 14psi(or whatever) wouldn't it still only make 14psi supply for the 4.2 and the rest would be 'bypassed' out the exhaust?

What about the turbo on the new 4.5 V8 diesel cruisers what are they running and wouldn't that be a suitable size?

PP

[DJR96]

Yes, the vanes in a VGT control boost. But it is all controlled electronically. Not just a set pressure either, pre-determined pressure to suit rpm, load, etc so it really works together with everything else. So the fuel injection is also programmed to do like the boost compensators do.

The 6.0 VGT is pretty big. Stock standard they pump nearly 30psi boost, and run something like 750cfm. That's A LOT! With a modified "tune" in the ecu, they can do heaps more, 40psi +. Oh, and if the vanes stick closed, it can spike boost pressure way up too, floating the heads even! Luckily there are ARP head studs that can handle huge boost, and all the bottom end handles it easily.:D This is the best pic I've got at the moment:-
http://i197.photobucket.com/albums/aa284/DJR96/Ford%20Navara/Firstfitupengineback.jpg

(It may not look it, but the compressor housing is about 8"diameter, 4" air inlet, 3" exhaust outlet.)

One off a 3.0 might work if a bit bigger compressor wheel can be fitted. You'd have to talk to someone that knows all the component interchangeability to be sure.

Of course the 4.5 LC would be closest (didn't think of that one did I:o). Again, getting the control over the vanes is the trick. Worth looking into some more.


OK. I'm just thinking out loud here so I may be way off the mark.;) I'm sure there would be ways and means of controling it more manually though. With the 6.0 VGT, the vanes are moved by a small hydraulic actuator (ram). The valve that controls the oil flow is a basically a solenoid spool valve. But if you were able to add a small diaphram, just like a wastegate actuator, to operate the tiny spool valve............ It would take a bit of fiddling around to get the right spring rate and everything. As well as setting it up. But it should work very accurately to what ever pressure it is set up for.

[Z()LTAN]

hehe Dave choo crazy

[DJR96]

Me :crazy:???

I shouldn't think out loud then should I.:o Too much insight to the way I think. But I think you all already knew that.:D

[Z()LTAN]

im sure its more than possible to do, epically for someone with your talents...

but still... sound like too much of a head phuck...

[DJR96]

Yeah. I'm justing thinking how to use one of these turbo's on a non-electronically controlled engine. Especially for Paddy who likes it all mechanical.

Another way to do it is to use a MAP sensor and some circuitry to control the solenoid valve. Which is probably easier if you can deal with electronics......

[Z()LTAN]

better of making a stand alone system that runs with engine rpm.

Im sure its not as hard as it sounds.

[zagan]

Can someone please explain the terminologies fo me.
Compound (2 exh manifolds feed 2 turbo's into 1 intake manifold??)
Sequential (1 exh manifold and a small turbo feeds a second bigger turbo on both exh and inlet side to bring boost early and carry it through??)
Is there another?

Cheers

PP

What you have to understand first is what a turbo is doing.

under normal NA engine running the max amount of air you'll ever get is 1 bar or 14.5PSI, this is what the earth's normal atmosphere is all the time.

When you use a turbo it compresses the air so you increase the atmospheres in the intake manifold, when this enters the cylinder and then gets combusted you end up getting more power due to the extra amount of oxygen you have put into the cylinder.

So with a diesel being an open throttle design, adding a turbo ends up being easy extra power, also with a diesel motor running a much higher compression ratio compared to a petrol motor, this also means a diesel motor is designed to handle a much higher amount of in-take pressure inside the motor.

most diesels will be coming out the factors at around 20:1 compression ratio, this is partly due to the turbo added at the factory and also the design of the diesel motor in the first place.

Which uses heated air and a squirt of diesel to ignite the air/fuel mix, the heated air comes from compressing the air in the cylinder.

Now when you add 1 turbo you can increase the amount of air in the cylinder, of cause the added amount of air is purely limited by how much the 1 turbo can compress the air.

a VGT turbo, can help a single turbo to simply spool up quicker, which can help to increase boost a little bit more or reduce turbo lag but will still only produce the same amount of boost as a non-VGT turbo.

going to a larger turbo will in cease the amount of air you can compress but you also require an extra amount of exhaust fumes to help produce the extra boost, which isn't always that easy.

with diesels always having an open throttle the turbo will always be spinning but with the lack of usable RPMs you may not get the larger turbo to spin quick enough, you'd be using the torque range for the usable RPMs for the turbo once your over that a diesel runs out of huff to keep things going.

to get around the 1 big turbo problem, you can use 2 turbos and you can compound them together to increase the total amount of PSI produced.

So for example you want a T4 but the diesel motor just ain't going to spin that baby up, you could instead use another smaller turbo to spin up the T4 instead.

How this would work is:
you would use a disco potato as the 2nd turbo
the T4 becomes the 1st turbo or primary turbo

the primary turbo is:
compressor side: hooked up to the compressed air out put of the 2nd turbo, then to the motor's intake manifold.

exhaust side: connected to the exhaust side of the 2nd turbo, and then out puts to the exhaust pipe

The 2nd turbo is :
compressor side: in-take is connected to the air box, out-put is connected to the in-take on the primary turbo.

exhaust side: is connected to the exhaust manifold, and will be out putting to the exhaust side of the primary turbo.


So the overall run down goes like this.

Air box
2nd turbo (compressed 1st time)
primary turbo (compressed 2nd time)
motor
exhaust side of 2nd turbo (quick spool up)
exhaust side of primary turbo
exhaust pipe

you really want to have a tricked out motor first for a compound setup, because you'll be inceasing the amount of pressure by a large amount.

say your at 40PSI of boost now have done the work on gaskets etc to handle that amount of boost if not extra boost all ready but really after 70PSI of boost, then you'd goto a compound setup.

and yes I have seen a diesel motor handle 90PSi of boost, a petrol motor would be lucky to handle 40 to 50 PSi of boost.

I've never seen any compound setup make use of a VGT set of turbos, as the ECU would go pretty hay wire if it started seeing 70+PSI of boost on the sensors.

and it'd be quite a bit of art to make everything work for the turbos and the sensors as your working with sort bits of piping.

Sequential turbos isn't compounding.

it's basically 2 single turbo setups on the 1 motor.

this works great for petrol motors that have 2 banks of cylinders, so V6 and V8 have 2 banks of 3 and 4 cylinders each.

They will either have all banks going to a single exhaust pipe or you can do a twin exhaust pipe setup which serves each bank separately.

A twin exhaust setup can help to increase HP in petrol motors as it reduces the back pressure on the motor.

so if you have a twin exhaust setup you could run 2 turbo separately from each other on each bank of exhaust manifolds.


Some people run a smaller turbo and then a large turbo, what happens here is the small turbo will have waste gate closed (producing boost) and the large turbo waste gate opened (no boost).

once you hit a certain amount of boost, it switches around so the small turbo waste gate Will stay open (no boost) but the large turbo waste gate will be closed (producing extra boost)

this isn't compound turbos, just 1 turbo making boost, only difference is that you swap turbos.

Edit:

I should add a compound turbo bolt on kit for the US diesel motors is between 3,000USD and 5,000USD so it's pretty cheap, to go compound if you really wondered but you'd want everything else upgraded in the motor to handle the much higher boost.

[Patrolling Paddy]

Well thanks for all that, it took some reading and I think I will need to read it again but I think I am starting to get a little bit of a handle on it.

I'm not really chasing outright power for racing type driving so I think that the compound turbo setup is not for me.

I would like to be able to achieve impressive power and mainly torque output from basically idle right through to flat out, which in a diesel of the 4.2L variety is about 4500rpm peak.

I think the VGT would allow the top end that I want and allow the bottom end that I like. However it may not be practical to get a VGT of suitable size and the hardest thing is the electrickery needed to run it.
For my application I am at the moment leaning toward the possibility of two turbo's slightly smaller than my current and setting them up so one starts and then they both run till flat out.
This should give me the quicker spool up from idle and then allow for the extra blow up top. The next trick is to work out how to control it safely and accurately.

The search continues.

I have been looking to source some VGT's off a 4.5L Toyota but so far I can't even find a model number to be looking for, can anyone help here?

Too many option not enough money to try them all.

PP

[Les Addison]

Hi Patrolling Paddy, If I could persuade you to talk to John Patrick in Townsville about twin turbos and the new ball bearing type turbos for these engines I feel he would put you on the right track, his paticulars are, John Patrick Turbo Supplies and Service 07 47215133. Hope this helps. Les