EGT and O2 sensors time resolution

[Bruce]

From: "Bernd Felsche" <bernie at innovative.iinet.net.au>
Subject: Re: EGT and O2 sensors time resolution
> Santi Udomkesmalee tapped away at the keyboard with:
> > 2 questions...
> > 1)  What sort of time resolution do EGT sensors, and O2 sensors have?
 
> O2 sensors can be faster than the stream of exhaust gas from the
> valve. Depending on type, placement and temperature, you're looking
> at response times in the region of 10 to 100 milliseconds.

Let's try the math on a v8 at 7,000 rpm single exhaust and sensor.
 
> EGT depends a great deal on the type of sensor and the exhaust gas
> temperature _gradients_. i.e. how quickly they rise and fall. The
> sensor has a finite response time dependent on its thermal mass.
> Response time to reach a "near enough" reading can be in the
> seconds.
> > 2)  Would a closed loop system be benificial to a high performance
> > application?  That is to say, ideally the engine should be at WOT
> > or idle most of the time.  Would there be any gains to
> > implementing some sort of closed loop system in this application?
> What sort of high-performance application? Aircraft?
> Just the usual benefits:
> Engine life, mainly. Also fuel consumption and engine power
> optimisation along with emission control.
> Other main benefit is that it allows more aggressive control
> strategies.

How so?.
Bruce

> BTW: An engine should never idle. That's 0% efficiency. :-)
 /"\  Bernd Felsche - Innovative Reckoning, Perth, Western Australia

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