Detonation Monitor

[David Hunt]

Exactly what are the archives?

Is it the ftp pages?

Have you looked at the web page lately?

I've downloaded the entire ftp site, but haven't found (yet) the info on
knock sensor.  I've followed every link on the website and haven't found
that info either.

I've read this response "There is a ton of good info., about this in the
archives already" many times and in many forms over the years.  And I used
to be able to find things, but now I can't.

I'm not complaining, I just need help if there is something I've overlooked.

dh

----- Original Message -----
From: "Bruce" <nacelp at bright.net>
To: <diy_efi at diy-efi.org>
Sent: Monday, May 28, 2001 7:53 PM
Subject: Re: Detonation Monitor


>
> There is a ton of good info., about this in the archives already.
> Bruce
>
>
>
> ----- Original Message -----
> From: "David Hunt" <bamainc at home.com>
> To: <diy_efi at diy-efi.org>
> Sent: Monday, May 28, 2001 5:40 PM
> Subject: Re: Detonation Monitor
>
>
> > Yeah, you're right (as you knew you were!) since the speed of sound
> doesn't
> > change with ocean depth. I've seen the waveform for the ping and it was
a
> > near sine wave that was much higher than the apparent audible frequency.
> >
> > Maybe it was the measuring device.  Piezo bolted directly to the head.
> The
> > pinging was caused by increasing the timing.  Increase by 1 or 2 degrees
> at
> > a time (not a trivial task) and wait for a minute or two.  The pinging
> would
> > start softly at first and then increase in apparent amplitude.  The
scope
> > said that the ping was simply more often, but always at the same
> amplitude.
> > Guessed is was because there was something heating in the combustion
> > chamber.
> >
> > I believe I recall a 30kHz fundamental ping frequency.  Does anyone have
> > better data?
> >
> > dh
> >
> > ----- Original Message -----
> > From: "Greg Hermann" <bearbvd at cmn.net>
> > To: <diy_efi at diy-efi.org>
> > Sent: Saturday, May 26, 2001 8:10 PM
> > Subject: Re: Detonation Monitor
> >
> >
> > > At 6:18 PM 5/26/01, David Hunt wrote:
> > > >I have been thinking about the detonation situation and you have
> ignited
> > > >some further thoughts on that subject.  You have mentioned that the
> > > >detonation frequency would be at about the combustion chamber
Helmholtz
> > > >frequency.  I think you're probably right but it just occurred to me
> that
> > > >the speed of sound should be quite high due to the compression ratio.
> > >
> > > Mach 1 (speed of sound) in any gas varies with molecular weight and
> square
> > > root of absolute temperature. Nothing else. NOT related to pressure!
> > > Obviously, Mach 1 will be increasing in the chamber during the
> combustion
> > > process.
> > >
> > > Greg
> > > >
> > > >So, if the volume is (for a 350 small block Chevy)
> > > >
> > > >350/8 * sine(degrees BTDC) + .125(350/8)
> > > >
> > > >where:
> > > >    The .125 is clearance volume for an 8:1 engine.)
> > > >    350/8 is the volume of one cylinder.
> > > >    sine(degrees BTDC) is the ratio of volume of the cylinder at that
> > position
> > > >
> > > >And the pressure is:
> > > >
> > > >14.7PSI * .8 * 8
> > > >
> > > >Where:
> > > >    14.7 is the initial pressure
> > > >    .8 is the volumetric efficiency
> > > >    8 is the compression ratio
> > > >
> > > >Then we should have the 'ping' frequency.  That's as far as I can go
> > right
> > > >now, I'll work more on it later.  I don't know the Helmholtz theorem
> > right
> > > >now.  But it seems that the ping frequency will increase depending on
> > > >where the ping is started in relationship to the cycle
> > > >
> > >
> > >
> >
>
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> >
> >
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