[Diy_efi] Peak cylinder pressure timing

Brian Michalk michalk at awpi.com
Tue Mar 4 21:12:51 GMT 2003


I am very interested.
What do you mean by the top of the housing?  Is the crystal inside the
combustion chamber?
Do you have any references?

> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
> Behalf Of Hugh Keir
> Sent: Tuesday, March 04, 2003 2:27 PM
> To: List for general do-it-yourself EFI talk
> Subject: [Diy_efi] Peak cylinder pressure timing
>
>
> There are a number of patents, some going back over 20 years covering the
> use of piezo crystals that use the spark plug ceramic as a piston to
> compress the piezo crystal against the top of the spark plug housing and
> allow you to read the cylinder pressure.
>
> There do not appear to be any systems in the marketplace that
> take advantage
> of this system for peak cylinder pressure readout.
>
> Optrand and Kistler make some more advanced systems that are US$3000 per
> spark plug - hardly suitable for the hobbyist.
>
> Having spoken to a piezo manufacturer, it appears that there are crystals
> that will give a good response and should stand the heat found at
> the top of
> the spark plug housing. Does anyone have any thoughts on why this is not
> do-able for the timing of peak cylinder pressure.
>
> 8000 RPM = 48,000 degrees crank rotation per second which should
> be readable
> to something close to 1 degree with a decent processor clock speed and a
> simple bit of averaging, compare it to the crank trigger and display the
> figure.
>
> Stands back and waits to be shot down!
>
> Hugh
>
>
>
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