I have a Jacobs E-brake so I took the easy route & installed the EGT probe in the brake housing. Seeing as how this is a post installation, at what temp. should I come off of it before the turbo starts to be in danger of being damaged? How much difference in temp. between pre & post?

 

As much as 450 degrees F, I've heard.
greg

 

From what I've seen on a truck with both a pre and a post, the difference will vary. The pre-turbo temperature seems to be much more responsive to temperature changes in the engine, while the post-turbo temperature changes are dampened by the turbo. The difference may be a small as 100 degrees F on level ground with no load and operating in the mid-temperature range (~600 degrees F). At the other extreme, with a load and accelerating on a hill, I've seen the pre-turbo guage quickly climb to 1200 while the post-turbo guage shows 700 and is slower to climb. With a load on a hill, it seems like the average difference between guages is around 300 degrees F.

 

There was almost 500* difference at WOT between the two. Normal cruising and idle was the same. Maybe 50* difference.

 

I run them both and as others have said, it can be anywhere from 0 to 600 degrees. It all depends on what you are doing and what you are hauling and where you are hailing it.
If yo want the best of both worlds then also install a Pre-Turbo Pyro. I us my post Pyro on my shutdown system to turn the truck off whrn it cool downs to 300 degrees.

 

Thank you everyone for your numbers. The problem I have is I don't understand the diesel engine any better than I do a womens mind. The egt probe is in the
body of the jake brake. It is only 4 to 6 in. down stream from the exhaust manifold where most of the pre turbo egt probes are. Do'es some of the hot gas go to the turbo & some go through the jake brake out the exhaust pipe? If thats so , how can it cool down 4-500 degrees in such a short time? Or is my thinking suspect.