Date: Tue, 7 Mar 2006 09:16:48 -0600
Reply-To: John Rodgers <inua@CHARTER.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Rodgers <inua@CHARTER.NET>
Subject: Re: "enough" vs "too much" monitoring,
was: permanent fuel pressure gauge
In-Reply-To: <04ea01c64193$87061ac0$6501a8c0@yoursz6x6sefxo>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I'm a big proponent of exhaust gas temperature gages (EGT). I have flown
many a piston powered airplane with the EGT installed, and lived through
the period in aviation when such first came on the market, first in the
airliners then they began to trickle into the general aviation market.
In the old days - in my time - only a cylinder head temperature gage was
installed with a single connection to a copper washer under a spark
plug. That was expanded to a washer under each plug - each connected to
the cockpit gage, with a selector switch so one could monitor the heat
on each cylinder. Later the gage would read all cylinder head temps at
once. The drawback was they were slow to respond to power changes. But
when everything was stable, the multi-temp readouts were reliable and
you could tell if a cylinder was running to hot - or cold. Later came
the first EGT systems, first with a single point sensor and gage set for
only one exhaust port, and later set ups were designed to read the
exhaust gas temperature just a few inches down stream from all the
exhaust port on the engine . These EGTS were highly accurate and since
the pilot manually controlled the fuel flow AND the mixture, he could
adjust the mixture - and therefore the temperature - of the exhaust. At
cruise, the pilot could - by watching the gage - set the power up for
rich best power, best power, and lean best power, depending on what he
was trying to accomplish - speed or range. He could - by watching that
gage and monitoring the exhaust gas temperature on each cylinder, set
the power by the leanest cylinder and thus avoid burning up that lean
cylinder.
I have often thought about how it would be to have such a system
installed on the Vanagon. Virtually all of the engines - both air cooled
and water cooled - could benefit from such a system. When cruising down
I-40 west of OK City I burned a piston and the engine failed. Had I had
an EGT system installed in my van that hot running cylinder would have
shown up long before things got to that point, and steps could have been
taken to avoid the problem.
EGT systems don't provide much useful information in city driving where
there is a lot of stop and go. But on the road, in cruise configuration,
they can tell you a lot about your engine. The ECU monitors and controls
fuel flow from data from the O2 sensor and other points, but it does not
do any monitoring and control using data from the hot exhaust at each
cylinder.
EGT systems on small aircraft consist of probes that are mounted by
drilling a hole in each exhaust stack just a couple of inches or so from
the exhaust pipe flange the distance of which is usually specified by
the manufacturer. The probe is inserted into the hole and thus into the
stream of the hottest ehaust gases and held in place by a stainless
steel strap or hose clamp. Simple really so I don't know why it could
not be done on a van. Maybe one day someone will test one out. on a
Vanagon.
Regards,
John Rodgers
88 GL Driver x2
ROBERT DONALDS wrote:
> Exhaust gas temp would show you how well each cylinder fires. This is not
> hard to do and as you said just look at an airplane cockpit and there you
> will see a exhuast gas temp gauge.
> and the ability to change the fuel mixture
>
> Bob Donalds
> Boston Engine
>
>
> ----- Original Message -----
> From: "John Bange" <jbange@GMAIL.COM>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Monday, March 06, 2006 7:58 PM
> Subject: "enough" vs "too much" monitoring, was: permanent fuel pressure
> gauge
>
>
>>
>> Maybe we should monitor every electrical connection back to lights on
>> the dash board. One for each injector, and a meter on each sensor.
>>
>
> Please, I beg of you, stop putting such good ideas into my crazy, crazy
> brain.. :)
>
> I think I want a window into each cylinder too, with a camera pointing at
> each, so I can monitor detonation...
>
> But on that note, what constitutes too much information? I'm pretty
> sure oil
> temp and pressure gauges cover the major operating variables missing from
> the stock system, but my little O2 sensor gauge allows me to watch my
> engine
> misfire subtly but regularly, explaining my low gas mileage... Look in
> the
> cockpit of even a small airplane, though, and you have gauges for
> EVERYTHING. Where do you draw the line?
> --
> John Bange
> '90 Vanagon - "Geldsauger"
>
>
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