new VNT turbo??
16-11-2004, 07:36 PM
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new VNT turbo??
saw this posted on another forum!
"VNT technology comes to GT Turbos!
A chap at RTOC who fiddles with turbos has managed to create a VNT turbo for the GTT. Typically used in diesels, these turbos are on the cutting edge of turbo technology and have been adopted by VAG and Renault on their current TD cars. Previously exhaust gas temperatures stopped such turbos from being used on petrol cars, however now with a bit of tinkering here and there it's been sorted...
What does this mean?
Well.. VNT turbos work in a way differently to normal turbos. Rather than having a wastegate which bleeds off boost to stop the turbo overspinning (i.e it limits how much boost it provides by leaking the excess gas), there are vanes in the exhaust housing. These are almost closed at low rpm and open up as more exhaust gases flow, therefore producing a quicker spool up and full boost earlier (i.e. it acts as an exhaust housing that changes size).
So in effect you have a turbo that spools quicker than a T2 yet provides the flow of a huge T3/4..."
"VNT technology comes to GT Turbos!
A chap at RTOC who fiddles with turbos has managed to create a VNT turbo for the GTT. Typically used in diesels, these turbos are on the cutting edge of turbo technology and have been adopted by VAG and Renault on their current TD cars. Previously exhaust gas temperatures stopped such turbos from being used on petrol cars, however now with a bit of tinkering here and there it's been sorted...
What does this mean?
Well.. VNT turbos work in a way differently to normal turbos. Rather than having a wastegate which bleeds off boost to stop the turbo overspinning (i.e it limits how much boost it provides by leaking the excess gas), there are vanes in the exhaust housing. These are almost closed at low rpm and open up as more exhaust gases flow, therefore producing a quicker spool up and full boost earlier (i.e. it acts as an exhaust housing that changes size).
So in effect you have a turbo that spools quicker than a T2 yet provides the flow of a huge T3/4..."
16-11-2004, 07:53 PM
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Originally Posted by markk
ive got a few VNT units , been using them for years on the diesels, they can have a few reliabilty issues thos with the vanes seizeing up 
what does VNT stand for too
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top idea though, aircraft engines been using them since the 60's
17-11-2004, 05:49 PM
#16
DEYTUKURJERBS
Originally Posted by MadMac
Originally Posted by Matt
huge T3/4
T3 aint that big Cool idea thou
Like we call T4s or GT35s massive, on some american chevy forums theyd be laughing at that comment when they using twin GT42s and shit...
17-11-2004, 07:50 PM
#17
Testing the future
VNT turbos work in a way differently to normal turbos. Rather than having a wastegate which bleeds off boost to stop the turbo overspinning (i.e it limits how much boost it provides by leaking the excess gas), there are vanes in the exhaust housing.
what is the typical EGT pre turbo on a diesel?
17-11-2004, 08:02 PM
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I messed around with a VNT-15 at Penn State during my FSAE days and didn't really think that much of them.
We had several problems with them.
First, the actuators available at the time were all for diesel engines, so we had to more or less fab our own setup, and that was a PITA with no data to work from.
Second, the vanes would chatter (oscillate) due to the clearances in the mechanism and cause huge flow stability problems. They also get carboned up if you run rich and require occasional maintenance.
I like the idea of how they work, just have yet to see it work as well in practice as it does in theory.
We had several problems with them.
First, the actuators available at the time were all for diesel engines, so we had to more or less fab our own setup, and that was a PITA with no data to work from.
Second, the vanes would chatter (oscillate) due to the clearances in the mechanism and cause huge flow stability problems. They also get carboned up if you run rich and require occasional maintenance.
I like the idea of how they work, just have yet to see it work as well in practice as it does in theory.
17-11-2004, 08:13 PM
#20
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actuator still operates the vanes... sure you didnt mistake it?
Diesel only go to about 700-800 degrees C ABSOULTLY on the limit! More like 300-400 most of the time.
Petrol is 600-800 normally, you run near 14.7:1 and its more like 1000 degrees at full chat!
alex
Diesel only go to about 700-800 degrees C ABSOULTLY on the limit! More like 300-400 most of the time.
Petrol is 600-800 normally, you run near 14.7:1 and its more like 1000 degrees at full chat!
alex
17-11-2004, 08:14 PM
#21
Testing the future
i can understand them not being used on factory cars if they aren't capable of huge mileage without maintenance. but i would have one on a yb if it had significant benfits, even if it needed maintenance like desooting or something every 5 or 10,000 miles (as that wouldn't even be once a year).
anyone know if that's a possibility, or do they just basically melt together?
how about on a less demanding application with a lower state of tune? i'm thinking twin turbo v6? as these VNT's are pretty cheap secondhand on the continent where there's many more diesels on the road.
anyone know if that's a possibility, or do they just basically melt together?
how about on a less demanding application with a lower state of tune? i'm thinking twin turbo v6? as these VNT's are pretty cheap secondhand on the continent where there's many more diesels on the road.
17-11-2004, 08:17 PM
#22
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they are common here...
but the heat is the issue.. the blades seize because of the temps.
Its all down to you EGTs, keep them low it might survive a while, same as a t3 will with mild anti-lag! But low EGTs arnt the way to power LOL
Alex
but the heat is the issue.. the blades seize because of the temps.
Its all down to you EGTs, keep them low it might survive a while, same as a t3 will with mild anti-lag! But low EGTs arnt the way to power LOL
Alex
17-11-2004, 08:18 PM
#23
Testing the future
cheers alex.
yeah, i see around 875 degrees EGT in my manifold straight out of the head. so it's not a whole lot more than peak for a diesel by the sounds of it.
and you're right, i could be mistaken about the actuator. i have seen an actuator but not really been able to see what it's operating as they're tucked up down the back of the engine on vw's and the driveshaft gets in the way of having a good look from underneath.
do bmw also use VNT's on there TD's? they have pretty sophisticated stuff normally.
yeah, i see around 875 degrees EGT in my manifold straight out of the head. so it's not a whole lot more than peak for a diesel by the sounds of it.
and you're right, i could be mistaken about the actuator. i have seen an actuator but not really been able to see what it's operating as they're tucked up down the back of the engine on vw's and the driveshaft gets in the way of having a good look from underneath.
do bmw also use VNT's on there TD's? they have pretty sophisticated stuff normally.
17-11-2004, 11:22 PM
#25
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We use them on all our TDCi engines in Dagenham, we get problems with them sticking too, but thats because of the tests we run on them. (i.e high revs for long periods of time) For Joe public, the vains will be moving all the time so there are less likely to stick. 
The latest Turbos use a little black box to control the veins (EVNT) so the ECU directly controls the veins via a small motor with a feedback circuit where as the old type are controled with a vacuum which in turn was controled by the ECU via a solenoid.
When i first took one of these Turbos appart i did it the wrong way up, and all the veins fell out, it took me ages to line it all up again!
The latest Turbos use a little black box to control the veins (EVNT) so the ECU directly controls the veins via a small motor with a feedback circuit where as the old type are controled with a vacuum which in turn was controled by the ECU via a solenoid.
When i first took one of these Turbos appart i did it the wrong way up, and all the veins fell out, it took me ages to line it all up again!
18-11-2004, 08:11 AM
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Engine Evaluation mate,
I'm the electrician in the area, i look after all the teardown, inspection, warranty, and the dyno cells. I also do the fault finding on the engines in the dynos, and when something is wrong i go and plug my laptop in and investigate
The new 2.7 V6 TDCi lump that goes in the Jag, Land Rover and Peugeot is really quiet and sounds lovely on full chat, for a diesel anyway
I'm the electrician in the area, i look after all the teardown, inspection, warranty, and the dyno cells. I also do the fault finding on the engines in the dynos, and when something is wrong i go and plug my laptop in and investigate
The new 2.7 V6 TDCi lump that goes in the Jag, Land Rover and Peugeot is really quiet and sounds lovely on full chat, for a diesel anyway
25-11-2004, 05:13 PM
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Yup, the Jag and the Peugeot are twin EVNT turbos and the Land Rover is a single EVNT turbo.
The Lion is a good engine but we are only shipping/selling 16 a day at the moment, and we are getting a few failures back with piston scuff but appart from that, all is good!
Where do you work now Alex?
The Lion is a good engine but we are only shipping/selling 16 a day at the moment, and we are getting a few failures back with piston scuff but appart from that, all is good!
Where do you work now Alex?
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