I just bought the new south performance EGT gauge kit. I had a block off plate tapped and threaded but was slightly off center. The probe doesn't go down all the way flush. stops about half the length of probe. Also is it alright for the probe to sit loose on the compression fitting? nothing seems to be holding the probe tight.
EGT prob question
- Thread starter Shello
- Start date
Digital Corpus
Top Post Dawg
The probe isn’t going further into the fitting because it isn’t straight. “Close enough” isn’t straight. If the compression fitting is loose, it is for the wrong size or you didn’t tighten the nut to compress the individual components, making a gas-tight system.
eddieleephd
Top Post Dawg
Or you didn't tap it deep enough...
The probe can be bent a little, if you pull the compression fitting from the plate and stick the probe all the way and tighten it you can bend it after to miss the manifold. Don't want it to touch because it's supposed to read exhaust gas temp, not manifold temp or some variation.
If you tapped it yourself you can straighten the tap out and re-tap it so that it's straight and this would be my preferred method.
Nevada_TDI
Top Post Dawg
Although centered is a good plan, tapping on a slight angle will allow more of the probe to reach into the exhaust stream and avoid touching the manifold.
Curious Chris
Top Post Dawg
I have a MycruiseAgent no drill EGT that goes down to with an inch or two of the turbo, you want the temperature there. Of course Mycruiseagent is gone but I am selling mine.
flee
Veteran Member
Or drill and tap the turbo housing to place the probe correctly.
It is unlikely you will get meaningful temperature data with the probe in the EGT bung.
It will read significantly lower and more importantly, IMO, the reading will be delayed.
I've had my probe tapped in both places and the difference is remarkable.
It is unlikely you will get meaningful temperature data with the probe in the EGT bung.
It will read significantly lower and more importantly, IMO, the reading will be delayed.
I've had my probe tapped in both places and the difference is remarkable.
eddieleephd
Top Post Dawg
It is a big difference when properly placed. I looked at the manifold and couldn't bring myself to go through all that. I put mine in the exhaust at the bend of the down pipe where it gets all the egts leaving the turbo. I don't think it's really worth tapping the manifold of every turbo. I made a bung out of mild steel pipe and welded it on. You can't get any more in the middle of the exhaust vapors and 2" after the turbine is damn close. Plus I can swap all the turbo's I want and have my thermocouple right there
crazyrunner33
Veteran Member
Placing the probe at the inlet of the turbo is the most accurate if you're looking for turbine inlet temperature and are concerned about running the turbo too hot. The outlet of the wheel experiences a massive temperature drop, even butting up right against the wheel.
Vince Waldon
Top Post Dawg
And, worse than that, it's a variable drop, since it depends on how hard the turbo is working... so you can't just add a fixed offset in your head.
It's a heat engine, and the Laws of Thermodynamics apply.
eddieleephd
Top Post Dawg
The laws of thermo dynamics state that the amount of energy consumed by the turbo is the amount converted to boost with a bit lost to dissipation.And, worse than that, it's a variable drop, since it depends on how hard the turbo is working... so you can't just add a fixed offset in your head.
It's a heat engine, and the Laws of Thermodynamics apply.
the outlet gives the temperature of the turbo better than the installation ahead which gives the temperature of the head and piston. Yes, it tells you exactly within the same difference of temperature what the turbo is experiencing. Do you know how much a heat energy turbo absorbs and holds? This is depicted by latent heats and when I look at the gauge it jumps just as quickly as ahead.
In comparison the manifold and the pipe have similar response and their values are much closer than the drop in from the egr block off placement.
As I said an energy benefit analysis told me that my installation is most appropriate for my needs. If I were running it on the track I would likely install two, one ahead and one behind the turbo and use the average to define the actual temperature of the turbo itself. This would be the most accurate way using egt alone. Now if we want to speak of the ultimate way to tell the temperature of the turbo we should be including an oil temperature sensor after the turbo to see what its internal temperature is and stick that in to the equation.
When I am reading the temperature after the turbo I am seeing temps dropping to the 250's rolling up to where I park, then they go back up when I stop. I attribute this to the turbo's temperature itself, even though the EGT's leaving the engine have cooled down the turbo can now heat them back up and show you where it's really at.
So in the end whether you stick the probe ahead or behind depends on what you're most concerned with. As a non-abused DD I'm concerned with the turbo itself.
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crazyrunner33
Veteran Member
Borgwarner uses turbine inlet temperature for their ratings, that is not only for the turbine wheel, but the housing even at the inlet of the turbo. They also place their themocouples at the inlet. For new installations, turbine inlet is the only way to go. Personally, I no longer run EGT gauges on my vehicles.
Vince Waldon
Top Post Dawg
Yes, it all depends on if you are trying to protect the turbo or the pistons.
My point is that there is not a "fixed" temperature differential between EGT at the inlet of the turbo vs at the outlet, since the amount of heat extracted will be a real-time variable based on how much power the turbo is producing at that moment. "That's" the laws of thermodynamics in operation.
TL;DR: one can't accurately say "just add 250F to the post-turbo reading to find out what the pre-turbo reading would have been if the sensor was mounted there".
My point is that there is not a "fixed" temperature differential between EGT at the inlet of the turbo vs at the outlet, since the amount of heat extracted will be a real-time variable based on how much power the turbo is producing at that moment. "That's" the laws of thermodynamics in operation.
TL;DR: one can't accurately say "just add 250F to the post-turbo reading to find out what the pre-turbo reading would have been if the sensor was mounted there".
eddieleephd
Top Post Dawg
Curious why they don't tap their turbo's per their recommendation and put a plug in...
Manufacturers do things based on the most extreme values, which is understandable. How often does one install two probes for the EGT average/difference? Like I said earlier the turbo temperature would be in between the upstream and down stream locations.
Why did you stop running gauges?
I have a McNally EGT/ boost gauge and optimal placement for the boost sensor was the egr delete plate, while I decided the optimum placement for my egr probe to be the exhaust pipe.
I think it would be interesting to install one ahead of the turbo and hook gauges to all three probes that would be installed then for a direct comparison of them. (egr delete plate never saw over 600degrees, ahead of turbo?, and behind Temps in the 700's cruising uphill{car only} and where I see it fall while driving slowly and rise once stopped)
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flee
Veteran Member
You took the easy way out and are trying -poorly- to justify it. Good luck with that.
Perhaps with your set-up you could do without EGT info which is what you are doing.
The only temperature data of any real-world consequence is the peak that the
turbine blades are exposed to and the duration of the exposure. Hence the mfr's info.
Sampling the post-turbo exhaust temperature tells you neither of these.
Perhaps with your set-up you could do without EGT info which is what you are doing.
The only temperature data of any real-world consequence is the peak that the
turbine blades are exposed to and the duration of the exposure. Hence the mfr's info.
Sampling the post-turbo exhaust temperature tells you neither of these.
eddie_1
Veteran Member
- Joined
- Dec 27, 2004
- TDI
- Jetta Wagon 2003 TDI tuned to 170HP, A6 Wagon 2008 TDI 2.7L tuned to 340HP
Here on the GTB2260VK it shows exactly the factory location for the EGT probe. i.e. right before entry into the hot side.
crazyrunner33
Veteran Member
Most manufactures don't install the plugs for the turbos to install a gauge because they don't think they'll ever exceed the turbine inlet temperature(TIT) rating, most modern turbos can handle over 1800 or 1900 degrees f sustained. Cummins performs their durability and burst tests for their turbos at around 2,800f, hence why they don't worry about the temperature in the real world. They monitor post turbo just for emission purposes.
I mainly stopped running the EGT gauge because I knew there's no way I'll go beyond the rating for my turbo(most modern turbos made after the mid 2000s are rated to over 1800 degrees sustained), especially after talking to one of the engineers who performs the destructive testing for BW. I'm running a modern BW turbo and have buried the 2000 degree EGT gauge that was on it for over a minute at a time when towing up a long grade. I just watch the water temperature instead, that's the tell tale for when you're about to break something. I installed a thermocouple in the factory PD140 EGT port and and made an arduino digital readout for my '06. I couldn't get that thing to budge much farther than 1800 when blasting up one of the grades, so I removed it to keep a clean looking interior.
For analyzing pre turbo and post turbo, I recommend going for a ride in a CR TDI. They do have a total of 4 EGT gauges I believe. Pre turbo, post turbo, pre DPF and post DPF if I recall correctly. It was interesting watching the differences between pre and post turbo, at some points even when not regenerating, post turbo temp at low throttle would almost match pre turbo. The closer the turbo was to its efficient zone of the map, the greater the difference was between pre and post turbo. Mine was stock, so I never really had a chance to see the difference when running the turbo towards its limit.
Vince Waldon
Top Post Dawg
Great info, thanks for posting.
I'd correlate it to:
Low engine power: turbo not working much -> not converting much heat into angular work (aka spinning the intake impeller) -> not much difference between pre and post temps.
High engine power: turbo working hard -> converting lots of heat into angular work -> bigger difference between pre and post temps.
eddie_1
Veteran Member
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- Jetta Wagon 2003 TDI tuned to 170HP, A6 Wagon 2008 TDI 2.7L tuned to 340HP
What kind of factor delta are we talking about pre/post at full load?
eddieleephd
Top Post Dawg
Exactly crazyrunner,
A turbo will begin to exhaust higher temperature's once soaked. The correlation to energy difference is proportionally the same as the temperature difference. Meaning the energy used plus the energy absorbed and dissipated through conversion and heat soak. If the post turbo temperature's begin to ride dramatically then your turbo is soaked and not cooling day enough.
Using the correct equation for entropy you can figure out where every bit of energy goes. Too much math so I'll use constants based on experience.
If my egt's get up to 1000 I will begin to worry about sustained boost then, as I watch the boost gauge and moderate that a bit more.
I'm running a VNT17 and getting ready to my recently received Wuzetem p502 nozzles to see how they perform. Got a good deal on Injectors from Dutch Auto and they're definitely clean OEM bodies and balanced in house.
I don't plan tow heavy loads and not putting it on the track, so pre-turbo isn't necessary as my great desire is to have reference and know how hot it is when shutting down. Through my understanding of physics and entropy, I can place proper value in those numbers realizing that at 23psi I have quite a bit of energy being converted into pressure in the form of boost.
So if your needs depict different readings do it and stop being stuck in criticism of others people.
Just makes you look like a douche, to critique in that manner.
Sent from my Armor_2 using Tapatalk
flee
Veteran Member
I'm experiencing an increase in entropy after reading the previous post.
eddie_1
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- Jetta Wagon 2003 TDI tuned to 170HP, A6 Wagon 2008 TDI 2.7L tuned to 340HP
Hi, Thanks for the tip. Should have paid more attention in the thermodynamics class first year. Since I was EE, I wasn't focused enough back then.
It's a pity there isn't a way to capture that extra EGT/EMP energy and make use of it at high rpm except melt the turbo or kill the bearings. A CVT(urbine) like wheel? dd15 truck engines have a second variable nozzle turbine geared to the timing gearset to recover some energy from the waste exhaust heat
used to be a bigger thing in aircraft engines, search for "turbo compounding"
otherwise there's always compound turbos for the more scoots
used to be a bigger thing in aircraft engines, search for "turbo compounding"
otherwise there's always compound turbos for the more scoots
Curious Chris
Top Post Dawg
The most fun is to put a thermocouple before and after the turbo. Then looking at the difference in temperature you can calculate the work that was done.