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Thread: Calculation A/R Ratio of Turbine Housing

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2011-06-11 02:51:57
Calculation A/R Ratio of Turbine Housing
I feel really stupid right now... So I have a turbonetics t4 turbine housing I had machined to fit my Holset HX40. I have the following numbers... Take into account the first two are rough, and the last one is solid. All measurements were taken by calipers and I rounded a little.

Why can't I get the right numbers??? It should be consistent or at least close across the board... and how can an area over a radius equal less than 1? Don't make sense!!!! ARRGGGGHHH

Area is cross sectional area of inlet, or anywhere along the path of the turbine... essentially perpendicular to turbine flow

Radius is radius from the center of the CHRA to the centroid of said cross sectional area...


Small Area
24.1 x 39.4 = 949.54 (Assumed wall thickness of 5mm)

Small Radius

Small Inlet A/R
949.54/50.7 = 18.72????

Large Area
37.7 x 51.7 = 1949.09 (Assumed wall thickness of 5mm)

Large Radius

Large Radius A/R
1949.09/61.7 = 31.59???

Turbine Inlet Area
77.2 x 48.7 = 3759.64 (Exact)

Turbine Inlet Radius

Turbine Inlet A/R
3759.64/73.44 = 51.19????
2011-06-11 02:52:57
Does this need to be in inches? I'm gonna be pissed.

Turbine Inlet Area
3.03in x 1.92in = 5.82in^2 (Exact)

Turbine Inlet Radius

Turbine Inlet A/R
5.82in/2.89 = 2.01????


Turbine Inlet Area
0.077 x 0.049 = 0.0038(Exact)

Turbine Inlet Radius

Turbine Inlet A/R
.0038/.073 = 0.0052????
Last edited by Meeners on 2011-06-11 at 03-04-07.
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