Vnt help

[Cbray2003]

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 

[Paul_13]

Look at piggy and volcane_zx's build threads

[Piggy]

You messaged me on FB?! Was that you?!

[Tom]

Just treat the vanes like a wastegate... Sort of.

[Dum-Dum]

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

[Cbray2003]

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 

[Cbray2003]

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 

[mr_fish]

Use a MBC, will make life a little easier

[Dum-Dum]

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.

[Cbray2003]

Ok yea well I've got a Mbc on order and then hopefully get it all bolted up and gd to go 

[Ruan]

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.

[Chairchild]

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).


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




But tbh... the power graph speaks for itself. It was toss

[MarkHam]

Does fitting a wg on a vnt turbo not slightly defeat the purpose of it?

[Chairchild]

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