<br>Thats all I care about but I was just going by Doug's comment that the gauge could be innacurate so be carefull. And he has a good point. We were also discussing the ways a pryo/thermocouple works thats all. No harm.

 

Johnh would you be more interested if your gage said 1725? or 1645? OverFueled<br><br>The first gage I had in had a probe of about 3/16 in dia, it did not do such a good job, it took for ever to get to 1300. When I changed out my turbo I went with a new pyro it had a 1/8 dia probe big difference in how fast the temp came up to 1650 and over at the blink of an eye. It does make a difference where it is placed how deep and the type used. OverFuled

 

It also deppends on the thickness of the thermocoupler shield. I once heard that Cummins uses a non shielded thermocouple on the dyno and you can see the heat pulses from the cylinders. Thats how fast the gauge moved. Very accurate but doesnt last long!

 

I assume most of you are assuming &quot;everybody&quot; has a pre-turbo EGT probe.<br><br>The original poster said he was hitting 1000 on a hill, not towing. With my 2001 HO, I could hit 1000, even 1050+, on a hill, not towing, POST turbo. Now that I've got a few &quot;light&quot; mods, I'm running a bit cooler, but I just thought I should mention the PRE-vs POST issue, so as to not confuse any newbies.<br><br>1250 pre-turbo is fine; even 1150 post turbo would really, really concern me...

 

I've hit 1350 post turbo unloaded on flat ground with a BHAF and 4&quot; straight pipe. That was without the comp plugged in. With comp in, I'm lucky to hit 950 post turbo.

 

[quote author=KATOOM link=board=4;threadid=15000;start=0#146604 date=1054936273]<br>I know quite well the difference between the two and the current I was speaking of is in millivolts. This current is produced by the copper wire and the chromealum...[/quote]<br><br>ahem: millivolts is a measure if volts, not current (current is measured in amps). As for the thermocouple producing &quot;millivolts&quot; however -- you are absolutely correct. The dissimilar metal junctions produce on the order of a few tens of microvolts per degrees C which puts the device in the low millivolt range for a 1000 degree F temperature. Out of the box, a thermocouple is not capable of producing ANY current because its leads are open (current = zero). But the voltage it produces (out of the box, and at zero current) is a well understood function of temperature and that is what engineers design around. Any current that the thermocouple itself produces is a consequence of the supporting circuitry within the gauge. So no, thermocouples do not produce current. They produce voltage. <br><br>[my previous comment] Again, the thermocouple voltage represents a temperature difference between one junction and a reference junction. For example, the Westach EGT guage is calibrated for a reference junction temperature of 70 degrees -- assuming that the reference junction will be located inside the cab. <br><br>You got it -- the gauge is not accurate unless the cab temperature is 70 degrees (this is for the Westach). But that is a pretty small error, given climate control and all of that. At most, you could be 10-20 degrees off -- big deal –- that's certainly a hair not worth splitting ;D My original point was only to make sure that the &quot;other&quot; junctions (the ends of the OEM thermocouple wires) are mounted in the cab and not under the hood. Under-hood temperatures can get pretty warm, and then you WOULD have an inaccuracy to worry about (150* under the hood means that your pyro reads 80* too low).<br><br><br>Agreed on the importance of placement -- again, if you put the &quot;other&quot; junctions in the cab then the error is insignificant and you're right -- temp readings come 100% from the tip, for all practical purposes. In reality, the thermocouple delivers (to the gauge circuitry) a voltage that corresponds to the temperature difference between the two ends of its own cable (one end is in the exhaust, the other is where ever you put it). If the &quot;other&quot; junctions are in the cab than we have nothing to worry about and most people don't even know or care about the error because its not important. But if the other junctions are under the hood, then your pyro is probably lying to you :-).<br><br>So what does that mean from a practical sense? Only this: Your pyro came with long leads -- put one end in your exhaust manifold and the other end in the cab – even if you splice additional wire onto them. Where those OEM wires touch copper is where the &quot;other&quot; junctions are -- often this is on the meter itself but it could be where you have spliced to another wire. The use of extension wires (if the thermocouple wires are not long enough for your install) is perfectly ok as long as the splice itself is in the cab. <br><br>I said all this because, while it is perfectly acceptable to extend the wires on the thermocouple (splice additional copper wire on to it), the temptation might be to put the splice itself out under the hood -- and that will result in an inaccurate EGT reading -- and it is enough to worry about.<br><br>All I'm out to do is expose the importance of the in-cab install -- to give maximum accuracy to your EGT readings. Put the ends of the OEM wires as close to climate controlled room temperature as possible. When you realize that the location of the thermocouple wire ends affects gauge accuracy, you begin to think differently about where they are routed and what temperatures they will see. Avoid proximity to heater vents, for example <br>