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Subject And taking it one step further >>>>>
     
Posted by Ash's Z on October 31, 2006 at 12:26 AM
  This message has been viewed 81 times.
     
In Reply To Hell, here's the effects just based on intercooler posted by Ash's Z on October 30, 2006 at 11:21 PM
     
Message .. adding in turbocharger discharge temperature based on different ambient temperatures...

Turbocharger Discharge Temp @ 60F and 90F Inlet Temp

90F Inlet Temp
14.5psi(a) inlet pressure
14.5psi(g) boost
74% efficiency
Discharge Temp: 251F, 121.7C

60F Inlet Temp
14.5psi(a) inlet pressure
14.5psi(g) boost
74% efficiency
Discharge Temp: 212F, 100C


Intercooler discharge density from turbo discharge temp, ambient temp, pressure, and IC efficiency:

90F Ambient Temp
14.5psi boost
121.7C turbo discharge temp
90% IC eff
32.2C (90F) ambient temp
41.15C ICTOUT
Density: 2.2137kg/m^3

60F Ambient Temp
14.5psi boost
100C discharge temp (212F)
90% IC eff
15.5 ambient temp (60F)
24C ICTOUT
Density: 2.3414

5.8% difference in actual air density at intercooler discharge
SAE is 3.3%
They disagree by 2.5%.

All the SAE correction factor is accounting for is the density of the air as ambient temperature and pressure change. Changes in humidity are also taken into account but I would imagine that the effect of changes in humidity are going to play a very small role as compared to temp and pressure. The calculations above are figuring what the difference in air density is at the intercooler discharge, which is essentially what the SAE correction factor is accounting for in the ambient air but you can clearly see that there are discrepencies when dealing with turbocharged and forced induction applications.




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