Hi Spartacus,

Adjusting the VNT limiting screw will determine how high your boost will go.

Adjusting the length of the actuator rod can be risky because it determines when, in the rev range that you get boost. You should never shorten the rod because that will increase your boost at low rpm. Making the rod longer will decrease the rate of spool up and limit boost at lower rpm. This adjustment is critical for turbocharger durability and could easily cause an overboost if you get it wrong.

 

good day patrol gurus, im just wondering what will be the effect in acceleration on a zd30 tdic engine if you adjust the vnt actuator lever by making it longer? and if adjusting the vnt screw by turning clockwise? counter clockwise?

Install a Dawes valve instead , easier ! :angel:

 

I think I am going to get Dawes valve as well.
I am sick and tyred of adjusting VNT screw all the time.
Where do you get needle valve from?
What else do I need?Couple of meters of hose and some conections,T's?

 

I think I am going to get Dawes valve as well.
I am sick and tyred of adjusting VNT screw all the time.
Where do you get needle valve from?
What else do I need?Couple of meters of hose and some conections,T's?

Alki

Southcotts , google them, they have the needle valve , apart from that not much else needed , i didnt run a tee off the boost line , i ran a new boost line for the Dawes on the Intercooler pips basiclly straight off the turbo , i did install the needle valve , but ive had no need to adjust it at all, i just the Dawes at the max bost i want at 3500rp (16-18PSI) the rest works like clockwork ..... Smooth boost curve as per Chazs diagram......

Cheers

Daz

 

Alki

Southcotts , google them, they have the needle valve , apart from that not much else needed , i didnt run a tee off the boost line , i ran a new boost line for the Dawes on the Intercooler pips basiclly straight off the turbo , i did install the needle valve , but ive had no need to adjust it at all, i just the Dawes at the max bost i want at 3500rp (16-18PSI) the rest works like clockwork ..... Smooth boost curve as per Chazs diagram......

Cheers

Daz

So,do You think that needle valve is necesary?

 

So,do You think that needle valve is necesary?

Hi alki, the dawes is great at setting your max boost, I like to still be able to alter my boost for low rpm (around town) and high rpm (highway) driving just like the ECU does.

I find that when I set my boost for town, it makes the turbo boost high when on the highway so the needle valve is used to re-set the boost curve on the fly by opening the needle valve a bit.

If you do not want the needle valve, the way around it is to set the grub to a compromise position for city and highway and use the dawes to limit the boost.

All the best,
Whitie

 

hi fellow patrollers, just an update, i had the egr blocked, adjusted the vnt screw half turn clockwise and had the vnt actuator lever adjusted with only 6 threads exposed from the top, ( this was altered sometime ago when i brought the truck to a service center ) i guess this is the standard length judging from the marking paint that was left...
max boost is around 1.2 bar and cruiseng at 100kph is around 0.3 bar, no more overboosting... is this figures with in the safe range?

 

Spartacus,

1.2bar is a very safe upper limit, but .3 could be a bit low as long as your EGT’s don’t creep up too much. Keep an eye on temps and it should all be good.

 

sir chaz, what should be the safe boost pressure when cruising at 100 kph? should i adjust the vnt screw anti clockwise? or the vnt lever? thanks...

 

g'day all,
under hard acceleration in 1st gear boost guage indicates 1.2 to 1.3 bar for a while and settles to .7 bar . Cruising at 100kph is now 0.4 bar @ 2000rpm with only me in the truck, and 0.5 bar at 110kph. egr blocked, standard exhaust, vnt screw 1/2 turn clockwise and has an automatic transmission. just want to know if 1.3 bar is my max boost or is this what they call "boost spiking" can i adjust my max boost further? what must be the max safe boost pressure then? i need your help guys...

 

sir chaz, what should be the safe boost pressure when cruising at 100 kph? should i adjust the vnt screw anti clockwise? or the vnt lever? thanks...

g'day all,
under hard acceleration in 1st gear boost guage indicates 1.2 to 1.3 bar for a while and settles to .7 bar . Cruising at 100kph is now 0.4 bar @ 2000rpm with only me in the truck, and 0.5 bar at 110kph. egr blocked, standard exhaust, vnt screw 1/2 turn clockwise and has an automatic transmission. just want to know if 1.3 bar is my max boost or is this what they call "boost spiking" can i adjust my max boost further? what must be the max safe boost pressure then? i need your help guys...

Hi Spartacus,
It sounds like you have it pretty good as it is, but just be carefull not to increase boost too much below 2000rpm in the interest of turbocharger life. I normally run around 10psi (0.7bar) at 2000rpm which is high enough to still give me reasonable EGT’s without creating unnecessary pressure.
1.3bar isn’t too high if that’s as high as it goes. Spikes will go up to 1.8bar and then settle to 1.4bar on a standard Patrol, so you’re well and truly in the safe zone, but keep an eye on EGT’s.

 

Hi Spartacus,
It sounds like you have it pretty good as it is, but just be carefull not to increase boost too much below 2000rpm in the interest of turbocharger life. I normally run around 10psi (0.7bar) at 2000rpm which is high enough to still give me reasonable EGT’s without creating unnecessary pressure.
1.3bar isn’t too high if that’s as high as it goes. Spikes will go up to 1.8bar and then settle to 1.4bar on a standard Patrol, so you’re well and truly in the safe zone, but keep an eye on EGT’s.

Hey Chaz,

just out of curiosity does, boost mean higher EGT's ? so more boosy equals more temps ?

Cheers

Daz

 

gday,
allow me chaz,
high boost lowers the EGT like mine(not me tho) like to run at 20 psi at 100kph and i have 450F temp. when the boost falls off to 5 psi or less the EGT go up to 600F.
its the opposite to a petrol engine. run a diesel lean= low EGT, run them rich = high EGT. but like petrol engines if u get the rite boost for the amount of fuel going in theres no problems. ( other than more boost that the motor/turbo was designed for)
i hope i made sense
vince

 

gday,
allow me chaz,
high boost lowers the EGT like mine(not me tho) like to run at 20 psi at 100kph and i have 450F temp. when the boost falls off to 5 psi or less the EGT go up to 600F.
its the opposite to a petrol engine. run a diesel lean= low EGT, run them rich = high EGT. but like petrol engines if u get the rite boost for the amount of fuel going in theres no problems. ( other than more boost that the motor/turbo was designed for)
i hope i made sense
vince

Good one Vince, for those who have blocked the EGR - I will add that whilst high boost sounds great at low rpms with low loads - you are actually restricting the exhaust and causing the motor to work less efficiently than it could.

This will not always be obvious but the motor will rev more freely and be more economical under those conditions with less boost.

:cheers:

 

Good one Vince, for those who have blocked the EGR - I will add that whilst high boost sounds great at low rpms with low loads - you are actually restricting the exhaust and causing the motor to work less efficiently than it could.

This will not always be obvious but the motor will rev more freely and be more economical under those conditions with less boost.

:cheers:

Thanks Vince and Whitie,
I was curious , as mine rarely goes over the 450 mark , than again i run 10PSI at 2000 RPM and 6PSI at 1500 or thereabouts + i do have the Dawes and Needle valve installed.

Was quite fiddly getting the right compromise of Boost etc @ certain RPM using the Needle valve and Dawes, but i think ive ogt it right for what need around town.

Now i must install the needle valve in Cabin , ! :driving:

Cheers

 

G’day Guys,

Vince and whitie, you’re both spot on. The problem with running high boost at low rpm is that the excess back pressure that’s created can damage the turbo not to mention unnecessarily loading up the engine.
Also I’ll add that with a petrol motor, you can run very high boost as long as you can get enough fuel into it. The boost will increase temps, but the fuel will cool it down again. As Vince said a diesel is the opposite and even though the air is compressed in the turbo, it doesn’t increase in heat as much as when it’s compressed in the cylinder. Pushing more air through a diesel engine will cool it down, but if the exhaust system can’t let it escape easily enough, you’ll get too much back pressure and actually loose power. This is where too much boost can have a negative affect and a free flowing exhaust can be a huge benefit.

Darren, you would have seen your temps go up when boost dropped before fitting the Dawes valve, but with the dawes fitted, boost doesn’t drop off and EGT’s stay at a reasonable level. The adjustability of the dawes valve is great, because you can set it up to suit your particular vehicle and the compromise is less.

I can’t remember the last time my EGT’s went over 250C in the city, but I managed to push it up to 400C the other day going up a hill at 100km/h on the highway.

Too good!

 

G’day Guys,

Vince and whitie, you’re both spot on. The problem with running high boost at low rpm is that the excess back pressure that’s created can damage the turbo not to mention unnecessarily loading up the engine.
Also I’ll add that with a petrol motor, you can run very high boost as long as you can get enough fuel into it. The boost will increase temps, but the fuel will cool it down again. As Vince said a diesel is the opposite and even though the air is compressed in the turbo, it doesn’t increase in heat as much as when it’s compressed in the cylinder. Pushing more air through a diesel engine will cool it down, but if the exhaust system can’t let it escape easily enough, you’ll get too much back pressure and actually loose power. This is where too much boost can have a negative affect and a free flowing exhaust can be a huge benefit.

Darren, you would have seen your temps go up when boost dropped before fitting the Dawes valve, but with the dawes fitted, boost doesn’t drop off and EGT’s stay at a reasonable level. The adjustability of the dawes valve is great, because you can set it up to suit your particular vehicle and the compromise is less.

I can’t remember the last time my EGT’s went over 250C in the city, but I managed to push it up to 400C the other day going up a hill at 100km/h on the highway.

Too good!

Hey Chaz,

how did u get yours so low going up a hill ? was that the combo of the Trans go ?

bare in mind my rigs full of Drawes and tools and ladders on the roof so im carrying a fair bit , ive reached 480Deg going up to Gosford and there is some very long steep hills Around town mine never goes over 200Deg C



Cheers

 

Hey Chaz,

how did u get yours so low going up a hill ? was that the combo of the Trans go ?

Hi Darren,
No, I don’t think so because the converter was locked. That fuel pump has made a difference. I use to get up to around 450 on similar hills.
I was following forum member sw1 and his temps were similar so maybe we had a tail wind LOL.

 

Hi Spartacus,
It sounds like you have it pretty good as it is, but just be carefull not to increase boost too much below 2000rpm in the interest of turbocharger life. I normally run around 10psi (0.7bar) at 2000rpm which is high enough to still give me reasonable EGT’s without creating unnecessary pressure.
1.3bar isn’t too high if that’s as high as it goes. Spikes will go up to 1.8bar and then settle to 1.4bar on a standard Patrol, so you’re well and truly in the safe zone, but keep an eye on EGT’s.

thanks chaz, i'll keep an eye on it...
cheers

 

Hey Chaz,

how did u get yours so low going up a hill ? was that the combo of the Trans go ?

bare in mind my rigs full of Drawes and tools and ladders on the roof so im carrying a fair bit , ive reached 480Deg going up to Gosford and there is some very long steep hills Around town mine never goes over 200Deg C



Cheers

Dawes must be reducing EGT a lot.
I got up to 600 Deg last week,half way up the hill (from Gosford ) and had to back off.
My car is loaded as well and boost is still under ECU control.
I got Dawes couple of days ago and am looking forward at fitting it.
From the drawings and pictures that I have seen,it shouldn't take more than 10 min to fit.
Only thing that I am unsure off is how do You bypass solenoid.
I'll have to do more search when Im ready to install it.

 

Dawes must be reducing EGT a lot.
I got up to 600 Deg last week,half way up the hill (from Gosford ) and had to back off.
My car is loaded as well and boost is still under ECU control.
I got Dawes couple of days ago and am looking forward at fitting it.
From the drawings and pictures that I have seen,it shouldn't take more than 10 min to fit.
Only thing that I am unsure off is how do You bypass solenoid.
I'll have to do more search when Im ready to install it.

It will take more than 10mins , id say an hour , then u need some testing and adjusting champ.....

 

So,do You think that needle valve is necesary?

Alki

personally yes , bcoz ive now got mine in cab, and i can adjust on the fly for city and freeway driving

Daz

 

It will take more than 10mins , id say an hour , then u need some testing and adjusting champ.....

Teeing boost line and vacum line and fitting Dawes shouldn't take long.
There is probobly some work involved in bypasing solenoid and offcourse setting max boost on Dawes.
It looks like it's going to rain tomorrow,so I might find time to do it.

 

Dawes must be reducing EGT a lot.
I got up to 600 Deg last week,half way up the hill (from Gosford ) and had to back off.
My car is loaded as well and boost is still under ECU control.
I got Dawes couple of days ago and am looking forward at fitting it.
From the drawings and pictures that I have seen,it shouldn't take more than 10 min to fit.
Only thing that I am unsure off is how do You bypass solenoid.
I'll have to do more search when Im ready to install it.

Alki,

It’s easy, all you do is run the needle valve to the air filter and swing the vacuum hose from the pump across the engine to the VNT actuator. So you’ll have no pipes going to the solenoid when it’s done. Then just join the pipe up like the pics and diagram on my page.

The Dawes won't necessarily lower EGT's, but depending how you set it up it can improve them because boost wont drop under power.

Good luck.

 

The Dawes won't necessarily lower EGT's, but depending how you set it up it can improve them because boost wont drop under power.


Yeah, I used wrong words.
Bypasing solenoid must reduce EGT's as it is allowing more (constant) boost at higher revs.