Pyrometer questions

[M215]

Hello SS,
Have some questions about installing a pyrometer on the M35A2. I'm confused on how the probe is connected to the gauge, they all appear to have electrical connections on the backs of the gauges. Are these available with mechanical connections, if so were can they be purchased? I ordered a pyro kit from a speed & custom shop, specified that it needed to be a mechanical set up. Unit arrived with only electrical connections, I checked with the manufacturer and it would not work with 24v. The ISSPRO gauges that appear on Ebay all have the same electrical connections.

Currently the exhaust manifold is off during a head gasket change out, I had the manifold drilled and tapped 1/8" NPT, hope that was the correct size.

Sorry if this has been covered before.
I appreciate any help, Karl

 

[PWM]

Karl

I went through the same problem when I was installing the pyrometer on my truck. I think the Isspro gauge that only used electricity for the light has been discontinued. I searched and could not find any, everyplace was sold out. I bought the Isspro R3607TR-AT. This is the kind that has an electronic sending unit. I was not able to find One that was 24 volts only 12 volts. I added a 12 to 24 volt converter that runs the gauge and is also wired to a cigarette lighter plug. I know that is not the anser you are looking for but it is an option if you can’t find the right gauge.

Pete

 

[Armada]

I got my pyrometer and boost gages from Hewitt Industries. The only thing electrical are the bulbs to light the gages, and they sent 24v bulbs for my application. The pyrometer uses a thermocouple to send the signal via a wire to the gage and doesn't require power.
1/8 npt is the right size for the thermocouple.

 

[jimk]

Gauges like the Isspro R607VW work electrically.
Isspro gauges with 4 digit numbers, like R3607VWR, have a separate 12V signal amplifier. I contacted Isspro to see it there make a 24V version. Tech said that I can use something like a zenier diode...These 4 digit gauges are called enhanced visibility.Tech said they get light thru the faces as apposed to around the edges.
Isspro has ,B/W,W, or w/color ranges for- pyro before turbo- or after. The cost is about the same.

I decided to use a 0-1200*F Isspro, pyro after, no amplifier. I want the widest needle sweep for accuracy,( granted a 3" would be even better) and no need for outside power (ex light). Simple is always better - less to fail,exsp. with all the vibration. I'm also concerned that when monitoring only half the cylinders EGT a fuel delivery problem could cause erroneous readings.

Mack used to put them after, for whatever that's worth where EGT runs 200-250*F cooler.

I have gotten a lot of great ideas/info here. Thanks all. JimK

 

[jimk]

Yesterday I tested (on the range) the Isspro R607-1200 I got on e-bay. My digital test gauge is very accurrate, and sensitive, but only goes to 500*F. It read ~25*F low 200-500. I used my 'scale of glowing iron' for 1000-1100*F. Less accurate, but got the expected results.

I did notice it takes a minute or two for it to react to changes.This may because it takes time for heat to reach the probe's core, or maybe the gauge slow to react to just a [change of] a few mv.This might be good to keep in mind when temp is still -climbing -near the upper limits.JimK

 

[houdel]

I bought the ISSPRO R3607TR pyrometer and then got the 24V parts directly from ISSPRO. The 24V bulbs were $1.42 each, the Zener diode was $7.50, plus $3.15 shipping for the lot. If you call the ISSPRO tech support number you can order the parts from them.

I went with the electrical gauge because they are SUPPOSED to be more accurate and faster to respond than the mechanical gauge. Also, the mechanical gauge does not correct for ambient temperature while the electric one does.

 

[Armada]

I did notice it takes a minute or two for it to react to changes.This may because it takes time for heat to reach the probe's core, or maybe the gauge slow to react to just a [change of] a few mv.This might be good to keep in mind when temp is still -climbing -near the upper limits.JimK

Hmmmm.... you would think the electrical gauge would be quicker to respond. The slow reaction could be from the nature of the test though.
The mechanical gauge I use is instant. Literally reacts to the rpms of the engine. Give the throttle a quick stab, it spikes the needle on the gauge as well.

 

[jimk]

My test was the problem. I just used a propane torch and got a 70*F to 900*F (gauge reading) in ~30 seconds(used the microwave as my timer). For 'temp rise speed' it appears high speed gasses in the exhaust will speed things up. EGT readings still lag but much less than my first test.

This link seems to offer similar findings:

http://72.14.209.104/search?q=cache...er+1200+thermocouple&hl=en&ct=clnk&cd=6&gl=us

or (in .pdf)

http://www.turbodieselregister.com/EGT_EVAL.pdf

Note: Their test went to 1700*F ~ 47sec.
Also a factor - propane torch's ~1700EGT is much hotter than a diesels.(latter would react slower)

JimK

 

[jimk]

Panel is Autometer, prometer has a post turbo probe. JimK