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+--- Thread: Vnt help (/showthread.php?tid=28508)
Vnt help - Cbray2003 - 30-12-2014
Hi there I've had a look threw the forum but can't seem to find what I'm after has anyone got a detailed link or pictures on how to control a vnt turbo to get the best out of it thanks
RE: Vnt help - Paul_13 - 30-12-2014
Look at piggy and volcane_zx's build threads
RE: Vnt help - Piggy - 30-12-2014
You messaged me on FB?! Was that you?!
RE: Vnt help - Tom - 30-12-2014
Just treat the vanes like a wastegate... Sort of.
RE: Vnt help - Dum-Dum - 30-12-2014
It depends on how you want to control it and what type of actuator you have.
If you wanna keep it simple you can use a boost actuator off an old turbo to push the vanes open at higher boost levels to control the boost level
If you wanna control it properly then you need to build an Ardunio ECU and fit a load of sensors
This is how to do it using a boost can.
https://www.youtube.com/watch?v=QtqfNFnnps4
RE: Vnt help - Cbray2003 - 30-12-2014
Thanks that's really helpful and that's how I'm goin to run it as electrics ain't my strong point and yes piggy it was me that messaged u on Facebook after I'd put this post up haha
RE: Vnt help - Cbray2003 - 31-12-2014
Ok then so got it all worked out that I'm goin to use it with boost pressure to control it rather than vacuum my last question just to make shore I'm still thinking Wright is do I adjust the actuator arm like a normal turbo the longer it is the less boost and the shorter for more boost plz correct me if wrong thanks
RE: Vnt help - mr_fish - 31-12-2014
Use a MBC, will make life a little easier
RE: Vnt help - Dum-Dum - 31-12-2014
Use the actuator arm and a manual boost controller.
Remember the standard VNT uses a vac actuator that at rest pushes the vanes fully open as a failsafe then pulls them shut to make boost when it wants it whereas your going to keep them shut at rest and push them open with boost to make less boost so your working it the opposite way but because one is a pull actuator and one is a push actuator you can just straight swap the boost actuator into where the vac actuator was, just trim and re tap the road and its 2 10mm nuts holding them on usually.
If you need to clock the turbo that is where it gets complicated as they have a pin to make sure they go together perfectly and even once you've removed that there is still only about 10 positions it can go together in because of the vane mechanism.
RE: Vnt help - Cbray2003 - 31-12-2014
Ok yea well I've got a Mbc on order and then hopefully get it all bolted up and gd to go
RE: Vnt help - Ruan - 01-01-2015
(31-12-2014, 12:36 PM)Dum-Dum Wrote: Use the actuator arm and a manual boost controller.
Remember the standard VNT uses a vac actuator that at rest pushes the vanes fully open as a failsafe then pulls them shut to make boost when it wants it whereas your going to keep them shut at rest and push them open with boost to make less boost so your working it the opposite way but because one is a pull actuator and one is a push actuator you can just straight swap the boost actuator into where the vac actuator was, just trim and re tap the road and its 2 10mm nuts holding them on usually.
If you need to clock the turbo that is where it gets complicated as they have a pin to make sure they go together perfectly and even once you've removed that there is still only about 10 positions it can go together in because of the vane mechanism.
That all changes on GTB turbochargers anyway, can clock to whatever angle you want. The vane mechanism is contained within the centre cartridge rather than in the turbine housing.
RE: Vnt help - Chairchild - 03-01-2015
when it comes to VNT control - the 3 options you have (in order of preference) are:
1) full electronic control - most commonly via an arduino. Requires a TPS, and MAP sensor as a minimum for any form of refinement.
2) set the vanes at a reasonable mid-point, then control boost with an external wastegate.
3) fit a boost actuator on, and suffer with all the drawbacks that brings
My Dissertation at uni was on a mechanical vnt controller - the same turbo controlled by a wastegate gave better power. I used a Saab GT1752, and fitted a Saab GT1849v hotside for the vnt version (GT18 turbine exducer was the same diameter, which meant it still worked as intended with the GT17 turbine wheel).
![[Image: comparativefullpower.jpg]](http://s8.photobucket.com/user/Chairchild/media/VNT%20stuff/comparativefullpower.jpg.html)
Blue = ran with no turbo
red = plain wastegate setup
green = the best the mechanical vnt control setup could muster
No intercooler was used, and the adaptor setup leaked like mad, hence the rather naff peak power, I will admit
![[Image: DSCN1302.jpg]](http://s8.photobucket.com/user/Chairchild/media/VNT%20stuff/DSCN1302.jpg.html)
![[Image: DSCN1238.jpg]](http://s8.photobucket.com/user/Chairchild/media/VNT%20stuff/DSCN1238.jpg.html)
But tbh... the power graph speaks for itself. It was toss
RE: Vnt help - MarkHam - 04-01-2015
Does fitting a wg on a vnt turbo not slightly defeat the purpose of it?
RE: Vnt help - Chairchild - 04-01-2015
indeed it does - but it also means you're not strangling the engine with excessive EMP, and you have vague control over the boost
As for the Arduino control setup - have a read through for some hints about general setup, and what's needed. Rover based stuff, but it's still just a diesel at the end of the day
http://forums.mg-rover.org/showthread.php?t=481026
The Rovers already have a MAP and TPS however, so you'd still need to bodge those on
