Exhaust A/R:

How is the A/R calculated for divided flange exhaust housings (T4 and bigger)? Normally you just measure the inlet area and divide that by the radius from the wheel center to the center of the place where the area was measured.
I ask this because I have a Holset turbine that is a 19 cm^2 housing that is divided. I can measure the area at the flange and measure the radius. This area measurement includes the area that is steel in the center (the divider).
Should I include the steel divider in the area calculation or measure just the two exhaust holes and calculate the area of the two holes to do the A/R?


Aftermarket wastegates:

How does a manufacturer rate an external wastegate? If a "6psi" spring is in the wastegate, would the gate start to open at 6psi or be fully open at 6psi?

Thanks,
J

 

I think you get what is called "creep" it starts toopen a bit before the actual 6 psi

 

Are you saying that they are rated at fully open? A "6psi" spring would mean that the actuator is fully open at "6psi". Correct?

Thanks,
J

 

I think that is correct....I am a little new to all this myself.

 

I checked the A/R thing. It really is the Area of the hole.