Hello! Just a quick question. But first you need to understand my problem. I got a GT2260V VNT from E6x 218 hp on E39 530d engine and looks like it is wrong adjusted by about 20 %. I converted VNT map from E6x software into E39 Software and it's doing it's stock full throttle pressure vom E6x at ~ 65 % instead of 45 % vnt duty cycle. Same in low-fuel scenario.. doing 80 % instead of 60 %.

The only problem is for those very little fuel scenarios like 15 or 25 mm³ of fuel. There it just goes up till 85 % duty cycle (I removed VNT limiter as a test to let him get what he needs) but even that is just not enough. It's already better than with vnt limiter, f.e. wanting 1,6 bar, getting 1,3 bar. Before removing limiter it was like 1,1 bar at 75 % duty cycle (all including atmospheric pressure), so only ~ 0,1 bar when wanting 0,6 bar. Now it's 0,3 bar because he can go till 85 % instead only 75 % VNT duty cycle.

From around 30 mm³/stroke upwards everything is fine, he is still at ~ 80 % duty cycle (going down with more and more fuel) but the more fuel gets the vnt boosting well and just makes the pressure as it needs. So after 30 mm³/stroke it does boost just right and with no over or underboosts, even boost at full throttle (80 mm³/stroke max.) comes very quickly and very accurate.

The only thing I would need to get the turbo running perfectly, would be to fix that low-fuel area where he just doesn't get the boost. I increased smoke limiter there by about 10 % and still car does not really smoke on those low fuel areas with not enough boost so I could be happy. But I'm a perfectionist and would like to fix that problem.

And now my question! :lol: Since those VNT maps start at 85 %, are those 85 % a technical limitation or could I f.e. change VNT map and VNT limiter to f.e. 90 %? So that it would start from 90 % down?

BUT..

I fear that it would be useless to go higher than 85 % because I think that the VNT arm from the turbo would be already sitting at max on that adjustable screw, at least it should be when correct adjusted regarding Garrett with around 600 mbar negative pressure which I have at idle speed (-0,7 actually).

Would my suggestion in the picture attached be plausible? Or do I have to move the screw upwards? Then I would start to turn that screw very little at a time and watch low-fuel boost behavior. When it reaches requested boost in low-fuel scenario, I would stop turning and adjust the rest of the vnt-map accordingly because it might overboost there then.

Thanks for your help!

Best regards, Thomas

hi , try to move the screw downwards , only shorts moves , 1/4 or 1/2 of turn max and try it . the more you move down , more close vnt , and more fast turbo charges