i know what the calculation is- cross sectional area of any point in the scroll (A), divided by the distance from the center of the wheel to the center of the cross sectional area taken (R).

on my 14b, i measured the diameter of the discharge at 33mm. the distance from the center of the wheel to the center of the discharge hole is 75mm.

A = area of a circle = pi * r(squared).
pi = 3.14.
33mm diameter = 16.5 radius (r).
A = 3.14 * 16.5(squared) = 854.9
R = 75
A / R = 854.9 / 75 = 11.4

wtf am i doing wrong? the discharge bends upwards a little so i measured inside the housing, and i ended up getting 31/51 => 14.8. both ways i get whole numbers!

the only way that seems remotely close is if i just divide the diameter (instead of the area) by the radius.

33/75 = 0.44

or

31/51 = 0.60

these sound much better but the ratio should be the same..

 

Try converting it to inches first

33 * 0.03937 = .65 inches cross-sectional radius

R = 75 * 0.03937 = 2.95 inches distance from center of the turbo to the cross-sectional radius

A = .65^2 *3.14 = 1.33

1.33 / 2.95 = ~.45 A/R

 

And if the measurements were precise, I'm sure it would've been around .42 A/R or .48 a/r since there is no such thing as a .44 a/r exhaust housing

 

ok that makes sense for the 14B i guess. now my t3 is 1.40625 / 4.3125 => .36A/R. ya its small. turbine housing says 0.63 A/R.

now for the trim the turbine calculation is confusing me. the compressor calc comes out fine - (inducer/exducer)^2 * 100. 46/60mm => 58trim.
the turbine calc - (exducer/inducer)^2 * 100. 58/48mm => 146?
converting to inches doesnt help (2.284/1.89)^2 * 100 = 146?