Fuel Econ and Hiway Mode

[Tedscj at aol.com]

OOPS,
read down a little farther and realized the matter was already cleared up.
Sorry!

In a message dated 10/12/00 11:50:27 PM Eastern Daylight Time, Tedscj at aol.com 
writes:

> > >I don't think he was implying that inert gasses aren't compressible,
>  >  >just that...more gas volume (but not more petrol) + same cylinder 
volume 
>  
>  =
>  >  >higher compression=better efficiency.   (of course, that's assuming 
all 
>  >  >other
>  >  >things being equal...which they never are!)
>  >  
>  >  Are you thinking that the EGR is in addition to the regular charge via 
>  >  pressure or something?  EGR replaces an equal volume of charge.  I 
don't 
>  see 
>  > 
>  >  any change in pressure.  I stand by my very-small-rocks theory.
>  >  
>  >  Jeremy
>  
>  No, you're missing it...
>  A given volume of petrol/air PLUS an additional volume of inert gas will 
>  yield higher pressure (once compressed to a fixed volume) than just the 
>  original volume of petrol/air.  Higher pressures extract more power from 
the 
> 
>  same mass of petrol/air, thus are more efficient.  The inert gas doesn't 
> need 
>  to be non-compressable or force-fed... Simply inducted as it normally is.
>  The other side of the coin is that the inert gasses lower the charge temp. 
>  (after it's in the chamber, by absorbing heat) thus LOWERING efficiency in 
>  that way (lowering the temp REDUCES the pressure).  Which factor governs, 
I 
>  don't know.
>  Of course, maybe I'M missing something being as I only took one semester 
of 
>  physics in college, a long time ago ;)
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