Does anyone know if a dual probe egt gauge is available? I like the idea of a pre-turbo reading, but I don't like the idea that I have to pick one side of the engine or another. I suppose the simple solution is to get two gauge sets but I don't have much real estate inside the cab for a bunch of gauges. Can I connect two probes to the same gauge and then see the highest value?

How important is it to take a pre-turbo reading? Should I just go with a post-turbo gauge and move on?

Extra credit question: My neighbor has a post turbo egt sensor on his 5.9 Cummins with a gauge that doesn't have any orange or red areas. He thinks he needs to stay under 1300 degrees but isn't that if your sensor is pre-turbo? I thought a post turbo set up should have a 1000 degree danger area? Is the Cummins set up different than our trucks where the pre-turbo and post-turbo have the same temps?

 

You really should go pre turbo with your probe. Its better to do a little more work now then to have to tear apart a block after you throw a rod.

Now on which side to choose from, I have no idea which side is better and have no idea if the gauge will just read the higher temp.

 

Go pre-turbo would be my suggestion. I run both pre and post turbo for comparison and from experience I see no reason to run post unless you are running them both.

 

Clay,

What kind of temp differences do you see at say 60mph between pre and post turbo? I thought the rule of thumb was to add 300 degrees if it is post turbo to be on the safe side?
Can you get just a pyro probe and not have to buy the whole works again?
I had someone else do mine way way back when and they put it post turbo probably because it was easy to get to.

Thanks
Lance

 

The difference between pre and post all depends on what you are doing. At idle you are about 50*F - 75*F cooler, cruising is about 100*F difference and pulling you can be anywhere from 300*F - 500*F difference.

You can just pull it out of the down-pipe and plug it as well when you move it.

 

it is a waste of time to run it post turbo. Pre turbo is the only way to go. That way you actually know what your motor is seeing, otherwise it is just a guess.

 

Thanks for all the comments. So, what are we concerned about when looking at the EGTs? What are high temps harmful to? Pistons, valves, turbo etc? What is the likelihood that one cylinder would get much hotter than all the rest? Does anyone have any real personal experience with melting parts? I believe that high temps are an issue, but how high is high and what is the ideal operating range supposed to be?

 

aluminim melts around 1200 degrees

 

Sorry, but you won't be able to do this. Each probe needs it's own gauge. 99% of folks just run one EGT gauge.

As it has been mentioned, pre-turbo is the way to go. As Clay pointed out, you can see a difference of 50 degrees or 500 degrees, depending on what you're doing.

Pistons are the first thing to go when EGT's get too hot. It's recommended not to go above 1250 for a sustained amount of time. People who drag race or sled pull will see temps go well above 1250, but they do it in short bursts of less than 20 seconds. If you're pulling a trailer over a mountain pass, and holding temps over 1250 for minutes at a time, then you're going to melt a piston sooner or later.

Can a cylinder run hotter than others? Yes, get a bad injector and it can happen. However there will usually be other symptoms to go along with it, such as smoke. But really the only way to monitor that with EGT's is to have separate probes at every cylinder, not just a probe on each side of the engine.

In the end, it's fine to just run one EGT probe on one side of the engine to get a good idea of what's happening. This is what most folks do.

 

You are safe to around 1350 degrees, if you see more than that back out of right quick as things begin to get liquidy after that. I've seen as high as 1150 towing uphill but no more. When my probe was post turbo the highest reading I saw was @600 post turbo is a waste of time at best. hope this helps.

Dan

 

International... Ya know the guys who built our motor...

1250* red line. You can tow all day at 1200 and not hurt a thing, but over that and your on your own...

Keep in mind when your looking at EGT's that it is an air temp measurement, not a metal temp. You have boundary air around the piston that is cooler, you have oil cooling jets spraying the bottom of the piston with cool (relatively) oil...

There is some fudge factor in there to play with. If your towing and at 600* and someone wants to play king of the hill, you have alot more time over the red line before bad things happen then if you were towing at 1100* for hours...

Understand?

Add to this...

I have both a right and left pyro, and can see as much as 100* difference at times. This could be due to probe placement and depth, air flow differences in the manifold or up pipe restrictions, lower compression cylinders...

So much to think about... Use some common sense and have fun...

 

Just a SWAG so feel free to shoot me down or shoot me at dawn.

Run 2 probes and 1 gauge. Hook it up to a switch so you can flip it one way and the input from the sensor in the pre turbo powers the gauge and you get a reading, switch it the other way and you get post turbo. Why you need both, I don't know but if someone must, that might be a way to accomplish it.

 

Great info. Thanks everyone.

So, as you can probably figure out....I am fixing to call Clay pretty soon and place an order for some more stuff.

Later this summer, I'll be pulling a heavy load up to a place called the Mogollon Rim to camp out for a couple of weeks. It's quite a steep pull in a couple of spots....long hard climb for a several miles. I am sure PaysonPSD knows the exact areas I am talking about....

At any rate, I've been doing this for years now without a EGT gauge so I have no idea if I've been torturing my engine or how high the exhaust temps have been. This year I'll have the egt gauge installed so I'll probably have a heart attack when I see what the temps are. My tranny temps get up to about 180 or so during the climb so maybe that is a good sign?

So, if the egt temps are at 1200 or below then I can be reasonable safe to just keep pulling away? What do I do if the temps climb higher than that? I normally pull those hills in 2nd gear anyway so my rpms are pretty high. Do I just back off the throttle and keep the shifter level pulled down into 2nd gear? I am trying to learn the solutions now so I don't have to learn myself for the very first time when I am going up those hills.

I am quite happy backing things down a bit if I have to but I wonder if there is a point where going too slow will do more harm than good. I would expect that I want to keep moving fast enough so the intercooler is getting plenty of air passing over it to cool the intake charge which should go a long way to keeping egts down...correct?

I normally run about 40-45 mph uphill with GVW right about 24,600 lbs (measured at the local CAT scales).

Thanks

 

1200* is fine... keep doing what your doing, RPM's lower EGT's. The more air you are moving the better. Do not lug the motor.

 

That could work. I would be suspect that it might change the temps a bit as pyros work on resistance... but who knows!