Im still pretty new to turbos but im confused about A/R numbers and trim.
I bought a car and the guy said its a t3/t4 .48 .62 turbo. So my question is the .48 the exhaust turbine of the turbo and the .62 the compressor turbine? Or is .48 the compressor size and the .62 is the compressor turbine?

 

.48 is the turbine housing size
.62 is the compressor housing size

there's an article on Garretts site explaining aspect ratios, wheel trim, etc. I'll find it and post it.

 

So do you mean the .48 turbine housing is the size of the hole where the turbine sits? And the .62 is the end of the turbo where it connects to the intercooler piping right?

 

https://www.turbobygarrett.com/turbo..._tech_advanced

 

No, these numbers are ratios. They dont denote an actual size or measurement, but rather the aspect ratio between different areas on the turbo. For example's sake a .48ar turbine is much smaller internally than a .82ar (AR = aspect ratio). The .62ar compressor is the same story...

Do some reading in the FAQ and in the links below...it will clarify your issue.

http://www.myturbodiesel.com/wiki/tu...sel-turbo-faq/
http://www.enginebasics.com/Advanced...explained.html