I need help, Probably mental help at this point.
I have been working with the compressor maps on the forums plotting rpm points. But I cant really understand for instance what a T-66 turbo actually is.
Is it a 66mm inducer/exducer, compressor side/turbine side?
Then when I think I got it figured out I notice there are several turbos that have the same wheel size and different A/Rs.
I know yall have probably gone through this before but I really can't find anything in my searches.
Would appreciate it if someone could straiten me out or point me to something that I can read.

 

Usually a turbo is sized by the compressor side, A t66 is just a 66 mm compressor. Compressors are sized based on the size and output of the engine. This is pretty common jargon across manufacturers: an s400 (s400 is a size family, they go from s200 through s500) can have a bunch of compressor sizes, and is usually termed something like s472 (72mm compressor) s480 (80mm compressor) and so on.
A family of compressors has a family of exhaust housings that go with it, in the case of the s400 there are quite a few options and it is normally stated as something like 83mm 1.10 A/R in T4 or T6 (which is the exhaust housing foot size). Exhaust housing side is used to modify the way a turbo spools or behaves under max load.

Compressor A/R doesnt matter too much in most of our applications so there is a good possibility the A/R you are reading about is actually the exhaust size A/R since its the easiest way to tweak power bands, and express the total size of the turbo in brief. A/R is an expression that talks about the dimensions of the turbo itself (Garrett explains it well here: https://www.turbobygarrett.com/turbobygarrett/turbine_housing_AR_and_housing_sizing)

Watch a youtube video on how to use matchbot, then go to http://www.turbos.bwauto.com/aftermarket/matchbot/index.html and play with it a little bit. It will help your understanding vastly.

 

Thanks Bud, Appreciate the help

 

Where can I find a compressor map for vs racing 78/75?

 

Not sure you can.
VS is the same as ON3. On3 says on there site. "We dont have compressor maps"

If you find any , please post a link for others.

 

The chart for the turbine sizing selector.
Is the the MM on the right (turbine wheel dia) of the inducer or exducer of the turbine?