Thread: VVT Control

Originally Posted by inside

Anyone done this elegantly? I have GT2256V that needs controlling, it works by operating the vanes under vacuum. It seems that there's a mod out there that allows mechanical control of the Patrol 3.0 VVT turbo.

Details here Manual Boost Controller
Kit here Nissan Patrol and VAG TDi

Looks like a cheap solution but am I right thinking this could easily work on the 4BD1 to control a VVT turbo?

I control mine with a pressure operated wastegate actuator, works a treat

I have a plan that is currently untested and retains the vacuum can.

It uses two feeds, vacuum from the vacuum pump and pressure from boost. An adjustable bleed valve on each with them Tee'd together into the vacuum can.

So no boost, the vacuum wins and vanes pull shut. As boost climbs it reduces the vacuum and opens the vanes. Use the bleed valves to tune it for both response time and boost level. You can then complicate it as much as you like with dawes valves, one way valves, pedal position valves etc.

It should work, but I haven't got around to trying it (I also have a GT2256V lying around) and I don't think anyone else has either.

Seems alot of ****ing around and a complex system for what is quite a dumb setup, I don't think there is much advantage, no engine braking to be had, just need the vanes to change to obtain full boost

Originally Posted by rovercare

Seems alot of ****ing around and a complex system for what is quite a dumb setup, I don't think there is much advantage, no engine braking to be had, just need the vanes to change to obtain full boost

If you want to change boost with a pressure actuator you are very limited. The vacuum systems give you full control. Which is why 90% of VNT setups use them. The other 9.9% are direct electronic control.

Pressure based VNT control is extremely rare. The HS2.8 is the only engine I'm aware of that used it.

Originally Posted by rovercare

Seems alot of ****ing around and a complex system for what is quite a dumb setup, I don't think there is much advantage, no engine braking to be had, just need the vanes to change to obtain full boost

But you don't need the vanes to change/any control to bring it to full boost.... the vanes could be positioned for minimum nozzle area, maximum nozzle area or anywhere inbetwen and it will still reach full boost.

The variable vanes allow you to vary the rate at which it reaches full boost whilst allowing it to not over boost.

Originally Posted by the_grubb

But you don't need the vanes to change/any control to bring it to full boost.... the vanes could be positioned for minimum nozzle area, maximum nozzle area or anywhere inbetwen and it will still reach full boost.

The variable vanes allow you to vary the rate at which it reaches full boost whilst allowing it to not over boost.

Ok so that explains why with the exact same fueling the vnt on mine with vanes locked shut will obtain 18psi, locked open makes 0 psi, but with a pressure can changing the vanes, makes 30 psi, ta for that

Originally Posted by rovercare

Ok so that explains why with the exact same fueling the vnt on mine with vanes locked shut will obtain 18psi, locked open makes 0 psi, but with a pressure can changing the vanes, makes 30 psi, ta for that

Ah good. Now we can get into some details on why to control it

So what your saying is that when fully open, the rate of change of boost is that low that it doesn't even over come inefficiencies?

And when it is fully shut, the rate of change of boost is that high that it hits a maximum of 18psi before flow restrictions limit any further boost?

So surely for optimal performance we would precisely control the vane position for maximum rate of change whilst not limiting maximum boost?

[EDIT rephrasing above line] So surely for optimal performance we would precisily control the vane for desired rate of change and desired amount of boost?

Originally Posted by inside

Anyone done this elegantly? I have GT2256V that needs controlling, it works by operating the vanes under vacuum. It seems that there's a mod out there that allows mechanical control of the Patrol 3.0 VVT turbo.

Details here Manual Boost Controller
Kit here Nissan Patrol and VAG TDi

Looks like a cheap solution but am I right thinking this could easily work on the 4BD1 to control a VVT turbo?

Yes this is a cheap and reliable control to get some performance out of a Variable Vane Turbo on a 4BD1.