From: ygmir (ygmir@onemain.com)
Date: Thu Sep 26 2002 - 08:14:45 PDT
Hi all,
The advise I got on installing a pyrometer, from an old timer here, is that
it is best installed close, but after, the turbo. There is info available as
to max. temperatures for distance "down stream" in the exhaust manifold, and
it usually drops by several hundred degrees. But, the chance of anything
breaking/falling off and destroying the turbo is essentially eliminated. My
pickup, for instance, has this configuration. The max temp for the location
of my sensor, is 900 Deg. F. As long as you know the maximum temperature, it
doesn't really matter what it is.
The reaction time of the pyrometer shouldn't be much of an issue, your
exhaust temp. doesn't change instantly. It seems it would be more important
to have something that would be most durable.
In theory, if you have a boost gauge, you use it to avoid overheating,
anyway. After a while, you will find maximum amounts of boost you can
handle, for a period of time, that will result in certain temps. For
example:
I find that in my truck, pulling, if I run much more than 15 lbs. of boost,
the exhaust temp. (and coolant) gets to high if I hold that for to long. For
short periods, it's fine, though. Boost, while driving, can be adjusted by
changing load/throttle settings.
Ok, I rambled, but it seems some folks are buying turbo-charged engines for
the first time, and maybe need some info to avoid unnecessary damage.
Henry
----- Original Message -----
From: "Bjorn Brandstedt" <super_deuce@hotmail.com>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Thursday, September 26, 2002 4:58 AM
Subject: Re: [MV] 24 volt pyrometer?
> Joe,
> The pyrometer consists of two parts, the dial indicator and the sensor
> (K-type thermocouple). The thermocouple generates a small voltage in
direct
> proportion to the temperature. This voltage is indicated on the dial,which
> is graduated in degrees F. The range will be about 200 at idle up to a
> maximum of 1200 degrees F or so. Never let the exhaust manifold
temperature
> exceed 1250 deg F! The only need for the 12 or 24 volts here is for
> illumination.
> The best way to install the thermocouple is to drill and tap the exhaust
> manifold at a point near the turbo inlet. You really need to remove the
> turbo first so that metal shavings will not fall into the turbine, which
may
> destroy it.
> The thermocouple tip must be of highest quality. A bad thermocouple may
get
> its tip burned off and destroy your turbo.
> There may be a way to install the thermocouple on the outside of the
> manifold, but the reading will have to be corrected by several hundred
> degrees and the response time fill not be good.
> If you do not want the dial permanently installed, you may use a Digital
> Voltmeter with an adapter for thermocouples and read the temperature on
the
> DVM.
> You may spend $30-$40 for the thermocouple and $100 for the DVM plus some
> for the adapter.
>
> The Boost gauge is nothing but a pressure gauge with its "sensing tube"
> plumbed into the intake manifold housing. There is a plugged tapped hole
in
> it, so that should be easy to fit with some copper tubing and a fitting.
> You should be able to make initial readings here using any gauge with a
> range of about 0 to 15 psi. Again the voltage would be for illumination
> only.
>
> The boost comes from burning more fuel. If you have too much fuel for the
> air supply then there will be lots of black smoke (= unburned fuel).
>
> When the turbo (LDT) version replaced the naturally aspirated (LD)
version,
> not much fuel was added. The additional air (boost) just made the
combustion
> more complete. The governor was adjusted to supply less fuel during sudden
> changes in demand to reduce black smoke during acceleration, which also
> reduced the torque some, probably. This was done with the "smoke limiting
> cam", which was set at a different angle on the LDT version.
>
> I'm getting carried away here...
>
> Good luck,
> Bjorn
>
>
>
> >From: "GOTAM35" <gotam35@sc.rr.com>
> >To: <mil-veh@mil-veh.org> (Military Vehicles Mailing List)
> >Subject: [MV] 24 volt pyrometer?
> >Date: Wed, 25 Sep 2002 23:54:14 -0400
> >
> >I want to thank all you guys for the advise about the diesel. One more
> >question. I went to "Truck Supply" today and checked on a pyrometer and
> >boost gauge. Everything they have is 12 volt. Do any of you have a 24
> >volt
> >gauge? If not how did you make the 12 volt gauge work? I can use my new
> >transformer but I didn't plan to keep it powered up all the time.
> >
> >Also what kind of boost pressure will this thing run? The gauges come in
> >two ranges, something like 0 to 25, or 5 to 50 somethings.
> >
> >The pyrometer will run me a little over $100. Can one be found cheaper?
> >
> >Thanks again for all the help,
> >Joe Trapp.
> >
> >
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>
>
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