6 cm2 = 0.41 A/R
7 cm2 = 0.49 A/R
8 cm2 = 0.57 A/R
9 cm2 = 0.65 A/R
10 cm2 = 0.73 A/R
11 cm2 = 0.81 A/R
12 cm2 = 0.89 A/R




Found that on stealth316's website.

T25 or T3 turbine housing?

I'm pretty sure those two numbers are referring to two very distinct and separate aspects of turbine geometry. That correlation may hold true for one particular turbine casting but that's it.

yes. we have the "As" given, but we do not know the "Rs" to give us the proper ratio.

For that chart to be useful, we would need to know which Garrett housings it is converting to. T25, T3, T4, etc. To compare nozzle/inlet area (which is the 6cm^2 designation) to A/R we need to know which housings you mean. It's entirely possible to have a T3 and a T4 housing with the same 0.63 A/R, but the T4 housing nozzle area will be larger than the T3's. So for example, the T3 0.63 A/R could be close to a 7cm^2 housing, whereas the T4 0.63 A/R could be closer to 10cm^2 (due to a bigger inlet). <--- prolly not exact conversions, shown for illustration puropses only, I performed no math to get these numbers, just estimations. HTH's -Chuck