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vnt turbo position understanding

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hey guys, im a little confused on my rg colorado vane position settings. iv watched the vnt webinar but im still confused at to with way i need to go for full flow and higher rpm?

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Andre can chime in on this one, but my understanding is that the x axis is rpm (of course), y axis is fuel demand (basically engine load), and the values in the table (Z axis) are proportional to how closed the vanes are. At a given rpm, the more closed the vanes, the more boost it will build. At higher rpm we want less closed vanes. With less closed vanes, we have reduced backpressure; and besides, at higher rpm there is more mass flow through the turbo to spool it.

Thanks raymond. I had a play yesterday with the logger and I'm getting down to about 7 degrees and hi load hi rpm. Seems to just be running out of boost capability.

I'm yet to tune a Colorado however the VNT position should be pretty standard. Raymond has summarised things nicely - Close the VNT position and you'll increase boost but at high rpm the turbo back pressure will quickly increase. I'd start by trying an overall increase of 10% to the fuel mass values you're using during WOT and moderate load and this will be sufficient to show the effect of a certain magnitude change. Remember that with a diesel engine boost is your friend as it leans the AFR and reduces combustion temperature. Be a little mindful though that some of the factory turbos are known to be weak and can fail if you raise the boost too far. We found this out the hard way with our Hilux unfortunately.

Thanks andre. I have a pretty good map in at the moment but I'm yet to put it on the dyno to confirm hp and tq. I just wondered if my increasing the vane position will actually gain hp or just rise boost due to exhaust restrictions thus increasing egt.

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