Help To Choose Correct Turbo

[nissan200sx.dk]

Hi.

Formula

Was sitting reading here, to lean some more stuff about these maps and how to use them. And after my second calculation i was tired of doing it so put the formulas into a xls docu and thought i would share it with you. Enjoy.

Calc

[T04GTR]

coool!! fits my t04z to a t

[discopotato03]

This could have been called compressor selection . Garrett aren't going to too much trouble to show how to work out the turbine side of the turbocharger equation . Also its very easy to fall into the trap of using their formula which shows up the maximums ie engine air requirement and compressor capacity at the redline .

I like to look at it as where the engines torque peak is and aim to have the compressors peak efficiency round about that point which is also supposed to line up with peak volumetric efficiency . Also note the compressor map with the port shroud map comparison on it . A lot of good aftermarket (did someone say HKS ?) turbos use them with good reason . Road car turbos with smallish turbines/housings tend to do this because the need to make them responsive often overspeeds the compressor in relation to how much air the engine can take initally . Note how the surge line is higher to the LHS in that case . Often the main difference between HKS and Garrett marketed BB turbos is the housings themselves . The HKS TO4Z is a good example . The fancy drilled and increased AR comp cover with diffuser alterations actually works . No doubt the turbine housing if tested back to back with the same AR Garrett diesel housing would work out better as well .

Cheers A .