Click here to enlarge Originally Posted by skyegirl Click here to enlarge
I need to make a correction (pardon the pun) to the definition of corrected speed in post #11 above. I stated 'corrected % speed' when I should have said 'corrected speed' for the equation as written.

Incidentally, does anyone know how the design-point corrected speed is defined for turbochargers? I think the design-point temperature may simply be sea-level standard day, but it would be good to have that confirmed. It would also be good to know the convention for setting the design point for turbocharger applications. Is it relative to a compressor 'redline' speed, say approx. 10% below this speed, with 15% surge margin?
Your starting to exceed my limited experience with turbo machinery. I thought test conditions are usually defined. But that is on the ones we get for our axial compressors at work. In this case they may be corrected for sea level and 15.5C but I have no evidence of this.

Here are some references. I've used to select base turbo sizes for my build.

Auto selectors.
http://www.turbos.bwauto.com/aftermarket/matchbot.aspx
http://www.turbobygarrett.com/turbob...t/boostadviser

Advanced tech info by garret.
http://www.turbobygarrett.com/turbob...bo_tech_expert

EDIT: Found this that says they are corrected by SAE guidlines to 14.696psia and 60f
http://www.forcedinductions.com/helpadvanced.htm