The turbo by its very function converts heat into work that means that the temperature goes down as a result. The more work taking place the greater the temp drop. Also the greater the expansion ratio the greater the temp drop.
I have always installed mine in the manifold. The way it was explained to me is what you're really worried about is your valves and valve seats and that is what you want to avoid damaging and it should only get cooler as it heads to the turbo so no worries there. Obviously race trucks and such might be a little different but those are few and far between. I actually always wondered if having an egt probe at each exhaust outlet (all moniterd by a computer and with setpoints so no having to watch 6 numbers would be the best) you could know each cylinder and possibly catch problems (such as a failing injector on a common rail) before totoal destruction...
So after I paused the video and added my comment and then continued to watch the video you made a comment about doing testing and modifying things on the lathe and then doing more testing. If you could set up cameras to catch this and then edit it down I am of the opinion it would be excellent content! Many of us love to learn and enjoy watching others fabricating and testing and documenting the results.
For many years truck manufacturers put the just after turbo as they were not as reliable as are now and sensor failure would destroy a turbo but some did like Mack put them pre turbo as they used to pull their engines down really low compared to most others at the time
The thing is; We measure EGT to get an estimate of the temperature INSIDE the combustion chamber... So i would think you want to be taking measurements as close to that area as feasible... The difference in temperature/pressure across the turbine is not linear. Its hard to say that the diff will be 'X' in all conditions... why add more variables/calculations while trying to collect data when you can just put it in a spot that eliminates those variables?
I learned from my dad who is a heavy duty mechanic and he has always put them in the down pipe and that’s where mine is. The thought was that if the probe ever fails it will take out the turbo. And you just know that it reads cooler so don’t let it run as hot. If mine goes over 1,000 I back out of the throttle and for the most part it runs at 675 empty and 850-900 with the trailer. But in my own experience after seeing 10’s of thousands of diesel pickups beat on their shit and never hearing of a probe failure. My next manifold will have an EGT probe in it instead of the down pipe.
Why even have a darn gauge if you need to estimate a guess as to what the true reading might* be. Besides ‘my dad said so’ What I’ve learned is that if you need to feel like you need to watch a gauge You’re already being more harsh on your engine than you know I should.
A turbocharger doesn't magically spin. It uses exhaust energy in the form of temperature differential and pressure differential to operate. Therefore the temperature will be lower after the turbocharger.
i have a friend whos a semi truck mechanic tell me that the egt probe should be at the downpipe and not at the exhaust manifold, Because the higher egt numbers will make you freak out. After watching this I think he just wants me to pay him to rebuild the 12 valve after I push the engine a little too far with that advice.
Big truck mechanic here, and for some reason in the big truck world they put them in the down pipe, ive yet to see one with an egt probe in the exhaust manifold and it bothers me lol
