Thread: GT2056V TD5 turbo boost control?

Try this Idea using a dawes valve for best results with Variable vein Turbo's.

This link will help. http://www.chaz.yellowfoot.org/Manua...Controller.htm

Cheers,
Brian

Thanks for that, but can I just hook boost up to it like a wastegate? That system seems to give you a linear boost map, which kind of defeats the purpose of a turbo in the first place!

You want full boost as soon as possible and held till the governor...

Originally Posted by *RR*

That system seems to give you a linear boost map, which kind of defeats the purpose of a turbo in the first place!

No, the Dawes system gives you maximum turbine speed down low, which is exactly what you want.

Originally Posted by *RR*

You want full boost as soon as possible and held till the governor...

I don't think that is ideal. If you are cruising along at 100 km/h you do not want full boost.

Assuming you have vacuum actuated vanes the answer is no you do not want boost on the actuator you want vacuum on it at idle and then at about 8-9 psi you want no vacuum. Ideally you want this transfer to happen linearly.

Originally Posted by inside

No, the Dawes system gives you maximum turbine speed down low, which is exactly what you want.


I don't think that is ideal. If you are cruising along at 100 km/h you do not want full boost.

Assuming you have vacuum actuated vanes the answer is no you do not want boost on the actuator you want vacuum on it at idle and then at about 8-9 psi you want no vacuum. Ideally you want this transfer to happen linearly.

*sigh* obviously, you don't want 25psi when your cruising, but NO turbo will operate that way, you need to have exhaust volume and flow to create boost, which is obviously dependent on throttle opening and load.

anyway, none of this answers my question. PS. diesels don't produce vacuum like a petrol hence the need for a vacuum pump.

To reiterate; can I just supply the vane actuator with boost (like a conventional wastegate actuator) for boost control?

Most VNT turbos have vacuum only actuators. No vacuum means the vanes are fully open (least boost), more vacuum means tighter vane position and more boost.

The simplest thing to try is two bleed valves. Vacuum to the actuator via a bleed valve and boost to the actuator via a bleed valve. I've intended to try this for a long time, but VNT turbos never size up well for my applications.

If it worked, the idea is vacuum pulls the vanes closed for more boost until you get enough boost leaking in to balance it out. Adjust the valves to find a good balance of response time and boost without huge air consumption.

Another layer could be added to the same system with a valve fed off the throttle pedal. So under full torque request it would reduce the boost signal further.

But VNT turbos are tricky. To get max performance you need them running with the vanes open at max power. Otherwise the efficiency of the turbine is terrible and it's an exhaust brake.
A VNT turbine that is too big and never gets it's vanes open can be a very bad thing.

Originally Posted by *RR*

To reiterate; can I just supply the vane actuator with boost (like a conventional wastegate actuator) for boost control?

Most VNT turbos operate on vacuum so if yours does then the answer is no.

No you can't just put your boost line to the vacuum actuator. However there are actuators that do operate on boost instead of vacuum. I think the Brazilian 2.8 came with such an actuator. The boost actuator would start with the vanes almost closed when sitting on the adjustment screw, then as boost comes on it starts to open the vanes up.

Ahhh, very good. Seems to be overly complex for a small amount of gain.

I wonder if you could use a normal boost operated actuator off a wastegated turbo?