I've got a pyrometer (autometer) waiting to be installed.
I know most people mount it pre-turbo, and some post.

What are the pros and cons of each set up?
I know that if the tip ever breaks off it will go through the turbo, but I have never heard/read of this happening.
Also, if you are messy with the drill shavings, they can hurt the turbo also.

Pre-turbo is supposed to be more responsive. Those egt's climb quick, so a few-second delay could be enough to cause disaster.

Mine's pre-turbo, and I've never seen a post turbo. The main reason mine's pre, is because it would have bothered me for the life of the truck thinking 'what could have been', and regretting my laziness.

To install, I separated the turbo from the manifold and put a piece of cardboard to block shavings. I started the truck and goosed it a couple of times with cardboard in place to blow anything out before reassembly.

i have mine pre turbo as well. better readings. downfall is install time. jus tbe carefull if you arent removing the turbo.
user some grease on the bit to catch the shavings. drill slow and stop and clean with q tips.

once through clean with q tips and magnet. should be fine. then tap with npt fitting.

if you chose to install post you would use the silver large tube clamp and simply drill a hole in the down pipe. but keep in mind your max egt will not want more than 800-900. or buy another pyro and run 2. lol. jiMMy

pyro serves 2 functions
1) cool down of turbo - pre or post function essentially the same
2) internal cylinder temperatures, pre turbo far surpasses due to physical seperation distance from the heat source.

mine's pre turbo, installation isn't a hassle, granted not a CTD but none the less you're drilling and tapping the exhaust manifold tool me a whole 10 min to accomplish the mounting and unless you've got a downpipe or other piece with a thick enough wall to drill and tap you'd have to weld on a threaded bung to do post turbo.

Pre gives truer combustion chamber temp and that is where the real damage can be done.

pre is the only way to go. I have data that shows thier can be as much as 600 degrees :mad3: diffrence between pre and post under ceartin conditions. I have never had or heard of anyone breaking a type k thermocouple off Travis

How come the big rigs have them post turbo?

How come the big rigs have them post turbo?

because of the tip breaking off. i know, guys will claim they never heard of it happening, I have, seen it with my own eyes.
Pulled plenty of thermocouplers out with no tips on them, if they had been preturbo, no more turbo.
maybe the guys who have never seen it have not been doing it long enough.
think about it, that thing is glowing red when under full load, hell my last OTR truck i owned and built the engine for would glow the whole manifold enough that it looked like the passenger side wheel well was on fire. I don't want that probe before the turbo on any of my rigs. If a customer insist it goes there, i will put it there. The breaking of problem is not as common on light duty trucks as the big rigs, but it does happen.

pre is the only way to go. I have data that shows thier can be as much as 600 degrees :mad3: diffrence between pre and post under ceartin conditions. I have never had or heard of anyone breaking a type k thermocouple off Travis

Guess that depends on how far down the probe is behind the turbo, and how close the other probe is the the exhaust valve.
I have seen, on one of my rigs that was NA, with a probe right at the exhaust port on the rear cylinder 1500 on the EGt's for extended periods. there are mosre considerations than just post or pre mounting. common sense on how far it is away goes along way. Somewhere i have a chart, probably like yours, but what i recall is 600degree drop for something like every 8 inches past the turbo it is, or soemthing along those lines, would have to go look it up again.
brian.

Well the temp drop is not just physical separation. The exhaust temperature will drop across the turbo because of the work performed. The temperature drop would not be consistent, but based on operating conditions.

Well mine is POST turbo. I haven't seen readings much over 700*. I have an edge ez on the 3rd setting, intake and exhaust. Even iIF there was a 600* differential, which I find hard to believe btw, I'm still in the safe range.

I've got a pyrometer (autometer) waiting to be installed.
I know most people mount it pre-turbo, and some post.

What are the pros and cons of each set up?
I know that if the tip ever breaks off it will go through the turbo, but I have never heard/read of this happening.
Also, if you are messy with the drill shavings, they can hurt the turbo also.

A better question is what is your gauge made for? Some gauges have color coding for post or pre turbo set up. Set it up what it was made for, if it is just numbers then do what you feel is best.

On my Scout turbo diesel, my pyro is set up post turbo. The main reasoning for that was the thermocouple. I have a custom flange on the turbo with 3" pipe, I think the port is about 3-4" back of the turbo out let. I never let my gauge go over 900 degrees, so basically I am figuring a 300 degree difference across the turbo. This is an assumption that is commonly excepted, but I am not really pushing high boost or doing anything else that would lead to excessive EGT's. I don't tow any considerable weight either. What I really like is it gives you a better idea of what temps are in the turbo for cool down and since I don't do anything that is really going to push my EGT's I feel it more important to know this, then the almost exact reading the pre turbo set up gives. I do have a port to run a pre turbo and have been toying with the idea of running two guages to really see what the difference is.

On my Dad's 93 Cummins it is a different story. It's pyro is installed pre-turbo. We did this because the truck is not only my Dad's DD, but also our tow rig and during summer time it hauls a camper all over the PNW. When we drive it, especially towing we need to know as best we can what the EGT's are. The pre set up gives you a way more reactive gauge, instantaneous. It is almost too much information, but you get use to it. The one negative is the fact that it does not show turbo temp very well as it is installed into the exhaust manifold per Cummins instructions. You start the truck and it jumps and hovers at 300 degrees. Even after long pulls when the truck is stopped it sits at 300. You could probably move it a bit close to the turbo and remidy it.


Good luck!

Install it before the turbo. There has been many good reasons listed already, but I want to say that there should be no worry about the thermocouple breaking off. I have installed literally hundreds of thermouples in exhaust manifolds at work and have run engines at work with fully instrumented manifolds. NEVER have I seen or heard of a thermocouple breaking off so its a non issue.

How come the big rigs have them post turbo?

Because the OEM's do not fuel the engine so heavily that they will run dangerously hot, so there's no need to be THAT precise.

Mine is in pre-turbo...wouldn't have it any other way.

Because the OEM's do not fuel the engine so heavily that they will run dangerously hot, so there's no need to be THAT precise.

Mine is in pre-turbo...wouldn't have it any other way.
LOL , Rich, some of those rig run WAY hotter than our trucks will ever run, especially under load.

i dont know about that. Stock for stock they may run warmer but throw some tuning to your pickup and i can bounce the little peg all day long on my 1600 gauge if i want

Travis

i have mine pre turbo as well. better readings. downfall is install time. jus tbe carefull if you arent removing the turbo.
user some grease on the bit to catch the shavings. drill slow and stop and clean with q tips.

once through clean with q tips and magnet. should be fine. then tap with npt fitting.

if you chose to install post you would use the silver large tube clamp and simply drill a hole in the down pipe. but keep in mind your max egt will not want more than 800-900. or buy another pyro and run 2. lol. jiMMy

I did what Jimmy did and I also taped a straw to the end of my shop vac and stuck it down the manifold to make sure I didn't have any junk left in there. Really didn't want to blow a turbo with less than 1000 miles on it! :laughing: