Any benifits to a post-turbo egt?

[rbattelle]

I don't really care what the pre turbo temp is, I know what the range of normal operation is for my truck and I live within those numbers. When I am going down the road I am not thinking that the gauge reads 600 so that is like 900 pre. I look at the temp and say 600 is normal.

---Doug

Amen to that!

 

[AMink]

I have mine pre-turbo, but this thread has me thinking. Dang thread! IF the probe is pre-turbo, and IF all is well in the turbo (oil, bearings, etc. ), wouldn't it necessarily be cooler at the turbo? I have noticed that even in cold weather and easy driving, it can take quite a while for my gauge to drop to 300. I have thought that the cast iron manifold is acting as a heat sink, and while the actual exhaust gases a cooler, the iron still has to cool. Figuring that post turbo would be a few hundred cooler, I shut down between 300-400. I suppose the turbo itself could be hotter than the gases too. I guess I need a turbo housing temp gauge! With fuel costs what they are, it's hard to sit for more than a few seconds without seeing $$$ puffing out the tailpipe! When I first got my probe installed, I caught myself shutting the truck off w/out looking. I'd turn the key back to see where the gauge was. HOLY COW! I had been shutting my truck off for over 100,000 miles when EGT's where over 500 and it still runs. Makes me wonder how many non TDR folks are doing the same thing. Probably tons. Last question in my ramble... does anyone have a pre and post running to the same gauge with a switch? I'd gladly put in another probe, just don't want another gauge. Thanks!

 

[MMead]

I think InThinAir is exactly right. Once you know what the safe range is for post-turbo temps, it doesn't matter what the numbers actually are. You could have a color coded egt gauge with no numbers at all and as long as you knew where the safe zone was there would be no problem. I think I'm going to do the easy install post-turbo, (not worry about metal shavings and broken probes), find out what the safe range is for post-turbo and stay between those numbers (whatever they may be).



Thanks InThinAir, I think I've finally made my decision and can get my gauges installed.

 

[Jeremiah]

Depends on what you want to measure

Pre-turbo will show escalating cylinder temps much quicker and be more responsive to temp changes. Post-turbo, should the probe ever break, the turbo won't eat it; I have never heard of this happening. If I put one on mine, it will be pre-turbo, otherwise you are guessing at cylinder temps, and I don't like to guess.

Let your conscience be your guide. It depends on what you want to measure. Want to measure cylinder temp, install pre-turbo. Wanna measure turbo exhaust to keep it from burning up? Install post-turbo. The vast - and I mean VAST - majority of people install post-turbo.

 

[rbattelle]

If you wanted to monitor the turbo then *ideally* you'd have a thermocouple on the bearing compartment of the turbo itself. Since that's not practical, a post-turbo EGT is the next best thing. But never forget that there is no air flow through the turbo bearing compartment, so an EGT gauge is only a marginal indicator of bearing temperature. Hmmm... maybe mounting an oil temperature probe in the turbo bearing oil outlet pipe would be an interesting exercise... . hmmmm...



People with a pre-turbo gauge can do the same thing, though. You simply let the truck idle until the gauge steadies itself, then idle for 30 seconds more (or thereabouts) to be sure the turbo has had a chance to cool too. What I'm trying to say is, a pre-turbo gauge can effectively accomplish the same task as a post-turbo gauge, you just have to use your brain.



I think John Q. Public pays absolutely no attention to turbo cooling time. I have a co-worker with a Subaru WRX who never idles the vehicle. My father had a LeBaron turbo years ago... never idled it. I was fueling up yesterday and a guy with a 2nd gen pulled in and shut off the engine before the truck even came to a complete stop. It's only dieselheads like us that really care.



Speaking of color-coding, here's a pic of my gauge. They also have one appropriately colored for pre-turbo EGTs...



-Ryan

 

[Bertram65]

If you wanted to monitor the turbo then *ideally* you'd have a thermocouple on the bearing compartment of the turbo itself. Since that's not practical, a post-turbo EGT is the next best thing. But never forget that there is no air flow through the turbo bearing compartment, so an EGT gauge is only a marginal indicator of bearing temperature. Hmmm... maybe mounting an oil temperature probe in the turbo bearing oil outlet pipe would be an interesting exercise... . hmmmm...



People with a pre-turbo gauge can do the same thing, though. You simply let the truck idle until the gauge steadies itself, then idle for 30 seconds more (or thereabouts) to be sure the turbo has had a chance to cool too. What I'm trying to say is, a pre-turbo gauge can effectively accomplish the same task as a post-turbo gauge, you just have to use your brain.



I think John Q. Public pays absolutely no attention to turbo cooling time. I have a co-worker with a Subaru WRX who never idles the vehicle. My father had a LeBaron turbo years ago... never idled it. I was fueling up yesterday and a guy with a 2nd gen pulled in and shut off the engine before the truck even came to a complete stop. It's only dieselheads like us that really care.



Speaking of color-coding, here's a pic of my gauge. They also have one appropriately colored for pre-turbo EGTs...



-Ryan

That's for sure about the average person not paying any attention to shut down temps, almost makes you wonder if it matters, with all the trucks being driven by people without gauges or any knowledge about cooling off before shutdown.

It is interesting as well, this is not the typical pre post thread, alot more civil.

 

[rbattelle]

That's for sure about the average person not paying any attention to shut down temps, almost makes you wonder if it matters, with all the trucks being driven by people without gauges or any knowledge about cooling off before shutdown.

Most people never read their owners manual either, and the cooldown recommendations are right there.



-Ryan

 

[DJaquez]

How do you like the lighting of the ISSAPro gauge at night? I have the Dipricol and the lighting is poor at night.



Dan

 

[JHardwick]

Not trying to flame here, but I have a really hard time believing that. If that's the case, then this afternoon while driving my STOCK 04. 5 home on the freeway with 6k behind me, I hit 1600*F pre-turbo????? I spiked the post mounted guage up to, and maybe even a little past 1100*F. I should be looking for a new engine right now instead of typing a response.

Not really. A gasoline or alcohol powered race engine with aluminum pistons, heads and block, can see 1600-1800* easily.



I may be wrong, but I think the heat is worse on the turbo than the pistons.

 

[DKarvwnaris]

How do you like the lighting of the ISSAPro gauge at night? I have the Dipricol and the lighting is poor at night.



Dan

I have Isspro gauges in mine, to be honest, they are too bright without colored boots over the bulbs. They irritate me when I am driving long distances at night. A friend of mine installed a tiny dial control knob in his gauge pillar to turn down the illumination to the bulbs, his are now at the same brightnesss as his instrument panel. I plan to do the same when I get a weekend free.

I am a post turbo fan personally, why take the chance with the probe snapping off? I don't look at the turbo as a seperate entity from the engine as its life will end only shortly before the engine sucks its grenaded parts and dies along with it. Temps behind the turbo are sufficient for me, I don't let it go much over 900.

I have a bank's brake on my dodge now, the top NPT hole was tapped for a pressure gauge, not the Pyro. I drill it out and tapped it to the larger 7/16" required for the pyro probe. More than enough material left to thread it afterwards.

 

[Jeremiah]

Cool-down

That's for sure about the average person not paying any attention to shut down temps, almost makes you wonder if it matters, with all the trucks being driven by people without gauges or any knowledge about cooling off before shutdown.

It is interesting as well, this is not the typical pre post thread, alot more civil.

I have to say that a post-turbo EGT gauge is revealing. I coudn't believe how quickly the temp jumped to beyond where it's safe to shut-down. Just pulling into my post office parking lot from a near idle approach is enough to jump it to 450 degrees or so. Sure glad I have the gauge.