[ClintJ]

Hey there everyone. I couldnt let this one pass. A variable turbine nozzled garrett from ebay and for a paltry some of only $136 AUD delivered..
Well it hasnt arrived yet but It will be overhauled and some mods made to the compressor housing around the inlet where the leading compressor blade edge is.
By machining a slight lip out of the housing so that the gap is bigger around that front blade allows a slightly higher boost pressure to be produced in the surge zone of the compressor map...
To explain compressor surge is exactly like cavitation of a ships propellor. Try to spin it to fast at a slow speed and the prop vibrates or effectively cant push any water until you slow the prop back down..
Same with the turbo compressor. Try to produce boost to early in the rev range with a compressor wheel that isnt designed to produce flow at that pressure and the compressor wheel goes into surge... By having a gap machined around the leading edge allows some of surge to be put of because the air can slip out to the side instead of trying to be compressed...
This turbo has come of a 3lt nissan turbo diesel
For those who dont know about variable turbine nozzles, then there are plenty of places to look for info like wikipedia or youtube for models..
But basically there is a set of vanes that control gas speed to the turbine by opening and closing. Make the gap small and the exhaust gas speed is high making the turbo speed up quickly. Open the gap up and the gas speed will slow down on the turbine wheel but as engine rpm gets higher you want less packpessure and higher flow rates so this turbo offers the best of both worlds.
That is quick to spool up to full boost and good exhaust flow at high RPM so that the engine power doesnt tapper off.