EGR questions...

[Jonathan R. Lusky]

Steve=Ravet%Prj=Eng%PCPD=Hou at bangate.compaq.com writes:
> 
> I was thinking about this last night...
> 
> What would be the effect of lots of EGR under part throttle conditions?  I was 
> thinking that might be a way to improve mileage say under highway driving 
> conditions.  My reasoning is this:  Adding exhaust gas to the intake would 
> dilute the A/F mixture, without changing the actual A/F ratio, since exhaust 
> doesn't contain oxygen or fuel.  Thus reducing the amount of fuel sent to the 
> engine, without the problems associated with a lean mixture.  comments anyone?

EGR displaces air, less air = lower volumetric efficiency = less power.
SO you open the throttle up to achieve the power output that you had
before introducing EGR and guess what, your airflow and consequently
fuel flow are higher than they were before introducing EGR.  EGR ain't
good for nothing cept reducing NOx emissions :).  Excess air (lean burn)
on the other hand does have fuel economy benefits.


-- 
Jonathan R. Lusky                        lusky at knuth.mtsu.edu
http://www.edge.net/~lusky/                 (615) 726-8700
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68 Camaro Convertible - 350 / TH350  \_/ 80 Toyota Celica - 20R / 5spd