AFM measurement/backpressure (was Turbo speed sensor)

[Espen Hilde]

Once its installed
> and calibrated then the conditions which lead to a immediate ignition
> retard can be 'pre-emptive' ie. a differentiator off the pressure sensor
> could initiate an interrupt for immediate retard by a set number of
> degrees - or even better, the differentiator sets the interrupt pulse
> width depending on rate of 'upward' change of pressure in exh before
turbo.
> 
> Once this is done a few times the s/w can 'learn' the pre-emptive point
> combination of AFM, engine speed, turbo estimate speed (if no turbo
> speed sensor) and thereby not advance the timing by the same amount if
> such a pre-emptive condition was detected - naturally the pressure sensor
> provides the final OK such that when pressure drops (turbo spooled up)
> and combination of AFM, speed etc then the advance can go up again.
> 
> Of course it would help heaps to have a turbo speed sensor as well which
> had a short gate time - like 10mS - it could report an output from 0
> to 25 for range idle to 150,000 rpm at blade... I think 100 samples per
> second would be fine given the rate of change of turbine wheel (i think)
> might be a little less then that...
> 
> Would this be a fair algorithisation of backpressure pressure sense for
> ignition retard on changing boost condition ?

Sounds good to me , but what do I know......
I think that what you can do with the trottle is making it difficult to
predict 
when things happen , the turbo lives its own life outside the engine 
and thats making it difficult.
I agree that measuring the turbo speed and backpressure is best ,if you 
know the speed and accleration of the turbo you know where its heading 
in advance.
I would love to get these things implemented in the 332 efi prodject.
please join and help getting the software suited for turbocharging.
Thanks 
Espen
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