Knock Question

[xxalexx at ix.netcom.com]

> From:          "Thor Johnson" <thormj at iname.com>
> To:            <diy_efi at efi332.eng.ohio-state.edu>
> Subject:       RE: Knock Question
> Date:          Fri, 20 Mar 1998 23:08:33 -0500
> Importance:    Normal
> Reply-to:      diy_efi at efi332.eng.ohio-state.edu

I think the original Bailey A/F meter worked on this principle
It burned on 100% H2 which ionizes everthing.
alex 
> > Heywood while referring to the measurement of ionization, leaves the
> > methodology to do so as an exercise for the student.  So what I am asking
> > for help on is any references to how to measure the ionization - SAE
> papers,
> > Reference books not leaving it as an exercise for the student etc.
> Circuit
> > Ideas for modifying the ignition would work. One idea that springs to mind
> > (I am absolutely positive it has been done before by someone!) is to use a
> > separate spark plug in the exhaust as an ionization detector.
> 
> Do this & I think you should be able to get some results:
> 
> Take a sparkplug & tap a hole for it in your exhaust (make sure electrode is
> in th stream).
> You may want to file the electrodes to pointy things or might not.  I dunno.
> 
> If you put a high voltage across it (you shouldn't need enough to arc), and
> measure the current, you should have something related to ionization in your
> exhaust stream (more current for a given voltage = more ions.  w/o arcing, I
> think you want to be in the somewhere in the 1-10uA ranges... I have no idea
> of the volage required).
> 
> If you're sneaky enough (Jacob's or A/C Delco research), you can use the
> real sparkplug as your sensor by monitoring the discharge cuve (& possibly
> keeping a high, nonarcing voltage on the plug to see ionization throughout
> the burn cycle).
> 
> I haven't tried these... but might soon ;)  (we might get to do more work on
> the Formula SAE entry we put together last year... whee)
> 
> -ThorJ
> 
> 
>