>I'm collecting, every 10 seconds at the moment,
>all 8 egt's and also a spread between coldest and hottest.
Is the data you are collecting every 10 seconds the average of the previous
10 seconds or a single measurement?
If its a single measurement I would suspect that you may be getting a bit
of noise that introduces some randomness into your samples. I don't know
how responsive your probes and A/D converter are but I think you will have
to sample more frequently and save the averages.
>What I'm getting though is variations when I didn't expect any.
>I.e. it'll be a 200 degree spread and all of a sudden jump to
>400 and then back to 200 ...
Are you using a carburetor or EFI? Most EFI systems do whats called
dithering. That is they cycle the mixture a little bit lean then a little
bit rich around the target mixture. This could also be the source of the
changes you are seeing.
>Is it possible that firing instances are such, occasionally,
>that one is just firing and another sucking cold?
I doubt your probes are fast enough to respond to a single misfire. Are you
seeing this randomness on all eight probes or just one or two?
>perhaps 10 seconds is too coarse?
I think 10 seconds should be OK if you are taking measurements more
frequently, averaging the measurements and then storing the average every
10 seconds.
If you are only recording a single measurement every 10 seconds that may be
too course. I don't know what EGT system you are using. There is the
possibility that it is already doing the averaging for you.
>... wondering if I'm totally off-base in my hope
>and quest of decreasing the chance of unexpected failure
>in this manner.
I think that EGT is a good way to monitor the operation of your engine. Its
been used for years in aviation and does clearly show certain failures.
Especially stuck or bad valve, misfiring plug, plugged injector etc.
I have been thinking about installing one for years but there always seems
to be a more pressing problem to soak up my budget...
>Thanks in advance for thought and comments.
Sounds like an interesting project. What software are you using to collect
your data? Are you recording RPM and intake manifold pressure? If so, you
should be able to create a good power/egt profile and maybe even use that
to spot slow trends. That would be interesting too.
Dave
>all 8 egt's and also a spread between coldest and hottest.
Is the data you are collecting every 10 seconds the average of the previous
10 seconds or a single measurement?
If its a single measurement I would suspect that you may be getting a bit
of noise that introduces some randomness into your samples. I don't know
how responsive your probes and A/D converter are but I think you will have
to sample more frequently and save the averages.
>What I'm getting though is variations when I didn't expect any.
>I.e. it'll be a 200 degree spread and all of a sudden jump to
>400 and then back to 200 ...
Are you using a carburetor or EFI? Most EFI systems do whats called
dithering. That is they cycle the mixture a little bit lean then a little
bit rich around the target mixture. This could also be the source of the
changes you are seeing.
>Is it possible that firing instances are such, occasionally,
>that one is just firing and another sucking cold?
I doubt your probes are fast enough to respond to a single misfire. Are you
seeing this randomness on all eight probes or just one or two?
>perhaps 10 seconds is too coarse?
I think 10 seconds should be OK if you are taking measurements more
frequently, averaging the measurements and then storing the average every
10 seconds.
If you are only recording a single measurement every 10 seconds that may be
too course. I don't know what EGT system you are using. There is the
possibility that it is already doing the averaging for you.
>... wondering if I'm totally off-base in my hope
>and quest of decreasing the chance of unexpected failure
>in this manner.
I think that EGT is a good way to monitor the operation of your engine. Its
been used for years in aviation and does clearly show certain failures.
Especially stuck or bad valve, misfiring plug, plugged injector etc.
I have been thinking about installing one for years but there always seems
to be a more pressing problem to soak up my budget...
>Thanks in advance for thought and comments.
Sounds like an interesting project. What software are you using to collect
your data? Are you recording RPM and intake manifold pressure? If so, you
should be able to create a good power/egt profile and maybe even use that
to spot slow trends. That would be interesting too.
Dave
