Placement of EGT probe

[Thunderbolt]

I have read here and elsewhere that the exhaust temp probe should be placed ahead of the turbo in the exhaust manifold to get a more accurate temp, quicker response. In my day job I see 7+ Big rigs per day. The majority do have Pyro gauges. The overwelming majority of them have the probes mounted downstream of the turbo in the down pipe. Any reason why?

I want to install a EGT gauge but I'm scared to drill the manifold.

 

[p-Bar]

drill it by #3 cylinder that one runs the hottest. start up the truck and drill a small pilot hole first nice and slow the pressure will blow the shavings out then drill the big hole, tap the hole the same way . Wear some eye protection

 

[nickleinonen]

they also run the probe 8"-12" post turbo. . with a set max of around 800f... most of them are also not hotrodded... pre turbo is more accurate. . the oem's don't recomend pre turbo as if you loose a probe tip, you most likely will loose a charger... post turbo will not damage the charger if the tip lets go.

 

[DHerzog]

I emailed Cummins before I installed my probe... they said to put it post turbo...



I drilled and tapped the elbow that goes from the turbo to the exhaust... . two clamps hold it in place. I marked where I wanted to drill, removed the elbow, drilled and tapped it and installed the probe, and installed the elbow in the truck... . less than two hours and I had never done it before.



That was a year ago and I never had a problem. easy to do, really. The down side is that the gauge responds a little slower than preturbo, and it does not get as hot... .





The max is supposed to be 1100 degrees, where preturbo is 1300 or 1400... . I really don't think it matters much... . I have never gone over 850 on a hot day towing up hill... . works for me.

 

[BIG BOB]

Hmmm, I've alway hear that #6 was the hottest, the main reason being is that it is in the rear of the engine and water is much hotter by the time it gets to the cylinder.



Here is where I mounted mine:



#ad

 

[JLovas]

Good question Thunderbolt... In all the farm trucks and tractors I own, all pyro's are mounted post turbo, as you mentioned. Based on this information, plus the fact that Cummins recomends a post turbo location, I installed my pyro post turbo. Its just that I use 1000 degrees as my max versus 1300 degrees max for a pre turbo mount. Plus there is no worries about getting shavings into the turbo.



On the other hand, the majority of owners here have their pyro's mounted pre-turbo and I don't recall hearing any problems. To each their own.

 

[2broke2smoke]

you guys forget that all the factory post turbo locations you've seen, and the recommendations from cummins all assume STOCK FUELING!!!



they have been designed to operate safely at max load ...



if you are installing a pyro to prevent overheating from aftermarket add ons then you want the quickest reading ...



i installed a pyro on a 24 valve motor that someone had purchased used ...

the pyro that came with the truck was installed about 10" downstream in the downpipe with a bung ...



the pre-turbo pyro was 600 degrees hotter!

 

[MCates]

It depends on what your application is going to be. I'm installing an EGT this weekend in the manifold because the temp readings are going to be most accurate and will read much quicker than post turbo, which is a must for my future performance upgrades. The turbo absorbs a portion of your heat energy in its operation. If you decide to install the probe into your manifold, lubricate your drill bits with a little grease to minimize small shavings from falling into your manifold. Using a small magnetic pick up tool to remove the rest during tapping. The instructions I received from Geno's recommend at #3 cylinder for location due to being as center line as possible without needing to worry about having FOD (Foreign Object Debris) entering your turbo during install. I recommend calling Geno's with any other questions you make have. You will find their number in our sponsors. Good luck!

 

[Dieselnerd]

Like many things about these trucks there are 2 good answers.

1. Power mods, mount it pre-turbo so you can make sure you don't have a melt down while you are giving it all that fuel and air.

2. Stock and staying stock, post-turbo is fine and a better place to make sure your turbo is cool before you shut down the engine.



Do what fits your particular situation and you'll be fine.

 

[jeepkid]

I mounted mine pre-turbo on my 04 and also on my old 94. When you drill it(pre-turbo) after you have the hole drilled, instead of using grease and a magnet just get a drinking straw and tape it onto the end of a shop-vac and just suck all the savings out. I did the magnet thing on the 94 and the vacuum on the 04 and the vacuum works a lot better and quicker.

 

[Scrappy]

Hmmm, I've alway hear that #6 was the hottest, the main reason being is that it is in the rear of the engine and water is much hotter by the time it gets to the cylinder.



Here is where I mounted mine:



#ad

that looks exactly like mine! (Minus the transmission dipstick) if you are going to use something like a TST their instructions say to put it pre- turbo so the egt based defueling reacts quicker.

 

[Thunderbolt]

Thanks to all who responded.

 

[JGrosso]

I have two EGT probes in my truck, the one for the Edge Attitude and one for a normal EGT gauge.



I have the Gauge probe mounted by the #3 cylinder, and the Edge mounted like the photo of Big Bobs. The gauge by #3 cylinder usually reads 50-100 degrees hotter than the Edge Attitude probe mounted closer to the turbo.



These respond quicker, and read hotter than post turbo, but if the Probe tip ever breaks off, it's going into the turbo.

 

[barleysoda]

Do any of you run one of those auto shutdown units that monitor the EGT and shuts off the truck once the temp is low enough?

Who makes a good "auto shutdown" unit and because of this unit does it change where I would mount the sensor... pre or post turbo?

 

[Scrappy]

I have an Isspro turbo temp monitor in mine, and the probe placement is different for it. Isspro recommends placing the probe post turbo so it is more accurately sensing the temp. of the turbo. I have gauges pre and monitor post, and if I shut down w/o the monitor the pre temp reading actually goes up 100- 150 deg. my monitor is set around 300 and the pre gauge is reading <300 alot sooner than the monitor.

 

[WUnderwood]

I thought the manifold was cast iron? Isnt that NON-magnetic?

 

[barleysoda]

I have an Isspro turbo temp monitor in mine, and the probe placement is different for it. Isspro recommends placing the probe post turbo so it is more accurately sensing the temp. of the turbo. I have gauges pre and monitor post, and if I shut down w/o the monitor the pre temp reading actually goes up 100- 150 deg. my monitor is set around 300 and the pre gauge is reading <300 alot sooner than the monitor.

Thanks for the info. Guess I have to mount two sensors if I want a gauge too.

 

[rbattelle]

Like many things about these trucks there are 2 good answers.

1. Power mods, mount it pre-turbo so you can make sure you don't have a melt down while you are giving it all that fuel and air.

2. Stock and staying stock, post-turbo is fine and a better place to make sure your turbo is cool before you shut down the engine.



Do what fits your particular situation and you'll be fine.

I think this is a great post, and I wholeheartedly agree with it.



And there is no such thing as "non magnetic iron" at room temperature under normal conditions. [At very high temperatures iron loses it's magnetic properties, but it would be hot enough to glow bright red. ]



-Ryan

 

[bigbob7777]

If you install the EGT probe post turbo, is the pipe heavy enough to be able to tap the threads? If not, do you weld a "nipple" to the pipe?



Also, post turbo, what temp do you use as a "time to let it cool down" setting? By this I mean when pulling a heavy load, (not shut off temp).

 

[Dieselnerd]

My probe is post turbo. The cast iron downpipe attached to the back of the turbo is plenty thick to tap, no need to weld anything to the pipe.



I normally shut mine down when the post turbo temp goes below 325 degrees. This often takes 3-4 minutes when the outside temps are in the high 70's to low 80's.