Understanding Compressor Maps...

[Josh-stateside]

I been keeping busy reading and searching. I happen to come across this page. This person wrote this thinking it's a k03 but it's actually a Rs2 compressor map.

Have fun reading

Cheers
Josh

http://www.gamesbbs.com/~vassago/compmaps.html

[Josh-stateside]

actually I am confused about which turbo map this is right now. but it's an audi turbo map and it's a decent page to read.

I have to admit I understand turbo maps a bit better now.

[Pisobiker]

Josh,
on top of the article is written the turbo is the k03 of the 1.8T Audi VW engines.

Now, about compressor maps, real problem is not reading the map, which is pretty simple once you have got the method. Main problem when applying to real engines is that all turbocharger manufacturers produce maps that represent compressor characteristics at "projected values" of temperature (To), pressure (Po), while P1t and P2t are pressures in the inlet of compressor and outlet of compressor which very seldom are well known values.
P1t, for example is not atmospherical pressure (Po) but is atmospherical pressure minus pressure drop in the intake duct before compressor (which isn't easy to mesure and vary a lot through the rpm);
P2t is pressure on the outlet of compressor which IS NOT pressure in the inlet manifold (which is the one read by ECU and any boost gauge we connect there), but could be significantly different.
Another very important parameter not easy to find is effective volumetric efficiency of the engine all the way through the rpm. 5% error in this mayght cause badly overspinnig the turbocharger on high rpm.

Second problem is coupling the compressor side with the right turbine. Turbine must develop enaugh mechanical power to drive compressor side at given flow and pressure, but AFAIK maps for turbines are almost impossible to find.
Normally manufacturer already makes a good matching between cold and hot sides (good compromise between lag and flow capabilityes), but if you are looking for maximum efficiencyes on top end power as much as on low rpm spooling capabilityes (thus looking for a "hybrid" solution) you definitly need turbine maps as well.


Marco