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surge limit is the lowest flow available at a certain pressure ratio, below that the compressor surges,(lot of heat). Pressure ratio is (atmospheric pressure+boost pressure)/atmos. pressure. Within each oval is a certain efficiency level. The smallest oval in the chart is high effienciency, each larger oval is lower efficiency. Most charts tell you the efficiency.
Very well said. Also, remember that the whole point of these maps is
to make sure that your turbo fan runs correctly at all
boost levels and flow rates. There's a cool little Java
applet over at [ http://www.turbofast.com.au ] that will
allow you to put in some parameters like engine displacement
and volumetric efficiency, and then show you where on the
map the engine is at different RPMs. So you can find out,
say, that your turbos are running within the 68% efficient
blob at 6000 RPM and 14 psi of boost.
-Ben
Ben Cantrick, mackys@dimensional.com
Black 1994 TT. |
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