Any benifits to a post-turbo egt?

[MMead]

I know the temperature readings will be lower than that actual temps if I install my egt probe post turbo. So my question is - are there any benefits to having the egt probe post turbo?

 

[DDahl]

Use it to monitor turbo cool down before shutting engine off. If you do not wait until post turbo egt is around 300 deg F you run the risk of carbonizing the turbo bearings (goodbye turbo).

 

[MMead]

But does the post-turbo egt probe do a better job of measuring the temps of the turbo than a pre-turbo probe?

 

[Bertram65]

But does the post-turbo egt probe do a better job of measuring the temps of the turbo than a pre-turbo probe?

Yes, there is no way a probe before the turbo can measure the temp of it. I want to monitor the temp of the turbo, to do this you have to have the gauge post turbo, it is what Cummins reconmends as well.

 

[Buffalo]

I have a '91. 5 W-250 (post turbo) and an '03, 3500 (pre turbo). the '91. 5 (w/ 16 sq. cm. turbo housing) takes a lot longer to cool down to 300 deg's. than the '03. I, often, have to wait for cool-down with the '91. 5 and almost never with the '03.

Joe F. (Buffalo)

 

[Bertram65]

I have a '91. 5 W-250 (post turbo) and an '03, 3500 (pre turbo). the '91. 5 (w/ 16 sq. cm. turbo housing) takes a lot longer to cool down to 300 deg's. than the '03. I, often, have to wait for cool-down with the '91. 5 and almost never with the '03.

Joe F. (Buffalo)

The pre turbo will show a lower temp sooner than the post turbo on the same truck when you stop and idle after a run to cool down.

 

[HParfitt]

Probably Post Turbo

I just got gauges. I have everything completed except drilling for the thermocouple. I didn't even consider doing post turbo at first. Now the more I think about it. Due to the fact that depending on where you put the thermocouple you only get temp on front cyclinders or back two. It seems, with the design of the stock manifold anyway, there is no place to put the thermocouple where it will see all 6 cylinders. So I am leaning toward going post turbo. At least you get an idea on all six cylinders. I figure if I did a pre turbo, with the thermocouple in the rear part of the flange above the turbo, and an injector hung up in the front I would see nothing. At least post turbo I might see some higher egt's. Just a thought.

 

[rashwor]

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.

 

[dodgerep]

post versus pre turbo pyrometer mounting

Pre turbo mounting has some deficits to it. first of all depending exactly where it is mounted. Where edge Recommends mounting it, the pyrometer would not be able to read the back three cylinders. That could result in a back cylinder burning up and the egt never measuring it. The second and least likely problem is if the thermostat actually got hot enough to melt off, I have been told it would require egts in excess of 1500 , and while not likely, if it happened, the little nipple would go clink clink just about the time the turbo went CLUNK CLUNK CHUNCK!@!!@$



Post Turbo gives a temperature reading of about 220 to 300 degrees cooler than Pre, but also give the temperature of the combined mechanics of the exhaust system. Just make sure you set your pyrometer guage to set off a warning about 300 degrees cooler and you will have no problem. It does give you a very good reading for cool down, and if you are patient eliminates the need for a cool down guage.



Mounting it on the elbow after the turbo is my reccommendation and with the common sense to adjust for the difference in temperature, it is a no brainer.

:--) :--)

 

[MMead]

For those of us with stock motors, I would think it would actually be better to have the probe post turbo since the chances of damaging your turbo after shutting down too soon would be greater than burning up a cylinder from running the motor to hard. I'm assuming, of course, that stock motors don't get the excessive temps that those with upgrades have.

 

[rbattelle]

What I'm about to expound on is only my opinion...



Personally I have my thermocouple mounted post-turbo. Eventually, I will also have one pre-turbo (when I get my ATS manifold some day). I believe there are 2 purposes for monitoring EGTs:



1. To avoid coking the oil in the turbo bearing compartment resulting in damage upon restart.



2. To avoid melting down an internal component of the engine.



Every single turbo vehicle on the road is susceptible to #1. In my *opinion* only people in "odd" circumstances are susceptible to #2. So what does "odd" mean? I mean people who tow very heavy at high altitudes in the mountains; or people who have a power-enhancing device; or people who have some internal fault in their fuel system that causes an over-fueled condition (example - stuck open injector).



So why was post-turbo the first gauge I put on? Well, the biggest reason is I'm too chicken to drill the manifold with the turbo in place and since I've always planned on an ATS manifold it would be easier to keep the stock manifold in nice condition as a "spare" and drill the ATS when I get it. Other reasons include the fact that I have no power enhancing devices, I don't tow anything, and my primary goal is monitoring the turbo.



The pre-vs-post argument is as old as time. The above is only my opinion, take it or leave it. I respect those who choose pre-turbo, and those who choose post-turbo. The best option is the one you research yourself and decide independently what to do!



On edit: Here's

a good thread that discusses it (read down a bit).

-Ryan

 

[JVolpe]

Well my Autometer pryo sensor is mounted pre-turbo top of manifold between 3 & 4. I have the Juice w/Attitude and I think I will mount the Juice pyro sensor post-turbo and have both.



How will ATS manifold installed pyro sensor be able to better monitor all cylinders. I thought it was compartmentalized more that the stock manifold. Maybe I just did not read the ATS manifold info correctly.

 

[JHardwick]

Post Turbo gives a temperature reading of about 220 to 300 degrees cooler than Pre, but also give the temperature of the combined mechanics of the exhaust system. Just make sure you set your pyrometer guage to set off a warning about 300 degrees cooler and you will have no problem. It does give you a very good reading for cool down, and if you are patient eliminates the need for a cool down guage.



Mounting it on the elbow after the turbo is my reccommendation and with the common sense to adjust for the difference in temperature, it is a no brainer.

:--) :--)

It's not a no brainer actually. The 300 degree difference is reference only, and according to the last TDR issue it is exponential. Depending on how hard you work the turbo , there could be a 500 degree difference



I'll keep my pre-turbo probe

 

[rbattelle]

How will ATS manifold installed pyro sensor be able to better monitor all cylinders.

I never said it would.



-Ryan

 

[klenger]

For those with a Jacobs exhaust brake, the brake is predrilled for an EGT probe, which makes post trubo easier to install.

 

[Vaughn MacKenzie]

300F is OLD SCHOOL

Post Turbo gives a temperature reading of about 220 to 300 degrees cooler than Pre, but also give the temperature of the combined mechanics of the exhaust system. Just make sure you set your pyrometer guage to set off a warning about 300 degrees cooler and you will have no problem.

JHardwick is right. The 300-degree rule does not apply to 3rd Gen trucks. Should be at least 500F difference to be safe, even higher if you're running more than a mild box and have a stock turbo.



I'd much rather take my chances hurting a turbo instead of an engine.



Vaughn

 

[Cattletrkr]

The 300-degree rule does not apply to 3rd Gen trucks. Should be at least 500F difference to be safe

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 to mention a week ago I hauled a load of trailers home from Southen Oklahoma, with at least 2/3 of the 860 miles spent with the EGT guage reading 800-900 and frequently going up to and over 1000*F.



Maybe the instant the throttle is stepped into, there's a larger difference, but it can't be a sustained difference, or I'd be really steamed right now (not to mention the truck)



I guess I'll find out in a few weeks once I get my Juice/Attitude installed. I plan on putting that probe pre just so I don't have to guess like this any more.

 

[DavidGardner]

So is the BD EX brake. I have one and all I had to do to install theproble for my egt temp guage was remove the plug and install the thermocouple. I would asume that all after market exh brakes would have the same feature.



Dave G.

 

[Vaughn MacKenzie]

Not trying to flame here, but I have a really hard time believing that. .

No flame taken Cattletrkr

Just trying to point out the 300F rule of thumb is outdated and it's not a safe assumption anymore.



The 3rd Gens do have more piston cooling than the 12 and 24v and can take more heat. But what's to say you're not doing harm by running your truck up to 1600F? Just because it didn't drop dead today doesn't mean some life hasn't been taken off the engine. 1600F is 1600F, that's mighty hot.



Vaughn

 

[InThinAir]

I know people talk a great deal about determining the pre-turbo temp with a post turbo gauge. I think that is a little silly. I have guages on 2 trucks both are POST turbo. 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.



And by the way, has there been anyone on this board to melt down a stock truck? I can tell you I don't really worry about it. I live in Colorado and haul heavy sometimes. I have seen 1100 Post Turbo in my 01 for 10 minutes, pulling max GCWR over Wolf creek Pass. It has 115k miles on it and that was 50k miles ago, now I do the same in the 03.



Again just my opinion and I am not saying that everyone will have the same result as me.



---Doug