I have had a few people ask me about upgrading a 16T to a 19T/20T so I thought I would put some photos up. In short, you need to rebuild the turbo (straight forward) which requires a rebuild kit, have the new wheel balanced with the old (maybe optional?) and machine the CHRA.
Below are some of my photos, but they are intended on being read together with a rebuild guide if you haven’t done one before.
The hardest bit was getting the compressor housing on/off, I ended up having to buy a pair of massive circlip pliers and even with them it was hard.
Once off, it looks like this:
Take the compressor wheel off. Remember, it is reverse threaded.
Take off the circlip, and gently pry up the seal. There is a rubber ring keeping it is place, but it should be pretty easy to get out.
Lift this thing out
Which should leave you this
At this point, the rest should be easy to get out. Here are most of the old bits
Get the new compressor wheel balanced with the old exhaust wheel (see far right on photo above for balanced wheels) and get the CHRA machined. To make the 19T/20T wheel to fit. Basically, the lip needs to be extended from 56 to 58mm. It is pretty obvious when you hold the new wheel against the old CHRA, but you can kind of see the fresh metal on the photo below:
Then you just gotta put it all back together, making sure to keep the parts aligned from when it was balanced…