GTB1749V from Darkside isn't a GTB1749V?

I've been running a GTB1749V from darkside developments for several years now, and have been pretty ok with its performance but I've never really measured how much of an improvement it got me. As of a week ago after an unfortunate intake mishap, I'm now looking to replace the cartridge since it's off balance and whining like crazy. So I took it all apart, and long story short the turbine measures 41mm at the inducer, which would make it a GTB1649V, not a GTB1749V.


Has anybody else taken this thing apart and measured the turbine? It's making it a real ***** to find the appropriate replacement cartridge, since there was never a proper model number on the turbo and now I'm not sure whether it's a gtb1749v or a gtb1649v. I'm concerned about the VNT housing fitting the 43mm turbine if I order a GTB1749V cartridge.


And since it seems relevant, does anybody know where to find a compatible cartridge, or have a model number of a turbo that uses the same cartridge?

As the turbo is custom made you wont find an 1:1 replacement except from Darkside, if they sell this as seperate item.

However, even IF you would find one, the more critical part on these Gen3 GTB turbos is the VNT calibration which would be set to default on a new cartridge.
On these GTB the setting is super sensitive, a 1/8 of a turn on the small min. flow worm screw makes the difference between "ok" and "fail".

This means you need the turbo to be calibrated on a flowbench after replacing the cartridge and as it is a custom made turbo you would need to know the current calibration as reference.
This needs to be done before dismantling the turbo, so this is probably to late now anyway.

Well the VNT vanes are controlled by an arm and the ring is fixed in place by a small pin going into the cartridge, so it seems to me that if the distance between that arm and the pin is carefully measured it should be sufficient to carry over that measurement to the new cartridge...is this not the case?

Its not the case. All parts have play and manufacturing tolerances, you wont tbe able to get smae result just by marking it.

What does Darkside say on the matter?
Can you send it back to them and have it refurbished or would it be cheaper to just buy another one?
I'm asking because I am considering one of their turbos.