[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Re: EGT, not relevent here - LONG

>Not to beat the dead horse, but I am comfused about things.
>1.  A faster spinning turbo does not make more air flow?  Obviuosly,
>there is a moment of peak efficiency for the turbo, and if you go beyond
>that there is no gain.  At least that is what I think you meant. 

Forgive my jumping in here, but I wanted to beat on the dead horse a little
bit.  Might as well do that at least once in my life...  :-) 

Based on these discussions, my understanding is that a turbo reaches a
certain efficiency level at a certain impeller speed.  Beyond that impeller
speed, a turbo generates air with greater pressure greater, but the air is
hotter and hence less dense.  This means that the total number of moles (?)
of air pumped by the turbo is less than when it is at its efficiency peak.

So, lets say you capture all the air compressed by a turbo at its most
efficient rpm level, over the course of 20 seconds in a big balloon.
Then capture the air produced by the turbo at a higher rpm level for
20 seconds in a second bag.  Now, the air in the second bag should be
hotter than the air in the first bag.  If you cool both bags to 25 degrees
Celsius, than the second bag (the air from the turbo spinning faster)
will be smaller than the first bag (the air from the turbo at its maximum
efficiency).  Smaller bag == less air.  So, just because the turbo is
generating a lot of air *pressure* doesn't necessarily mean it is getting
a lot of air into the engine, if it is over-shooting the rpms at which
it is most efficient.

So, the question is: am I correct??  If not, where did I go wrong?

'85 Coupe GT
Eric J. Fluhr                                Email:  ejfluhr@austin.ibm.com
630FP Logic/Circuit Design                   Phone:  (512) 838-7589
IBM Microelectronics Div.                    Austin, TX