AFM measurement/backpressure (was Turbo speed sensor)

[Seth]

Yes, the heat energy is higher, but hot inert gases don't burn or
explode.  As you start increasing the quantity of EGR, you will increase
the charge temp, but reduce the concentration of oxygen. So at 50% EGR
for example, you could, using your numbers, arrive with 250C intake
charge, assuming no losses of heat. And 10.5% O2. Which would certainly
be hot. But probably wouldn't even light, let alone knock. And I bet
pumped, metered EGR is less that 400C.  Even EGR due to the exhaust
valve being open during the intake "event" has time to cool nad expand
further while it is waffling about in the manifold and exhaust port.

-Seth

Bernd Felsche wrote:
> 
> nacelp writes:
> 
> >> EGT is significant; the energy in the recirculated exhaust gases
> >> will increase the possibility of knock as the total energy of the
> >> mixture is higher than with all fresh mixture.
> 
> >EGR, is low in O2 content, so how is it's total energy higher?.
> 
> It's hotter.
> 
> The total energy of the mixture in the cylinder is higher.
> 
> The exhaust gases are at 400C or more. The fresh air is at maybe
> 100C with a turbo and inter-cooler. Therefore the total energy is
> greater at the end of compression, prior to the start of combustion.
> 
> You start with a hotter mixture, so you need to compensate for that
> to avoid knock.
> 
> --
> Real Name: Bernd Felsche
>     Email: nospam.bernie at perth.DIALix.com.au
>      http://www.perth.dialix.com.au/~bernie - Private HP
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