Originally Posted by Boosted Z

It is more than likely a T4 .58 then, and that is very small and is the reason you are spooling that quick with a turbo that is that far from the engine.

R&D on my end (on the VQ) shows that you need a T4 .81 for about 600whp (DJ) on pump, and .96 a/r if you wish to push things past that. (.58 T4 = .7x T3)

I find it very funny when a manufacturer says "600hp" turbo. That is great, but it is only the rating of the compressor wheel, and not the turbine. So you have a large compressor that will flow 65lbs/min of air, but you have a turbine housing that can only flow 50lbs/min....and THAT limits you to about 500hp. So you can have a turbo (compressor) that is rated to 1000hp, but if the turbine stays the same, all you will get out of it is 500hp.

Fluid dynamics will never cheat you, but somebody selling something will.