I know pre turbo is better than post turbo, but what is the difference in temps. Ihave somebuddies that work on big trucks and they say that it dosent matter.

 

i beleive the temp is higher after the turbo, plus your not reading the heat that the turbo is actually receiving from the motor. thats what i was told by someone who knew more then i did at the time

 

The heat will be higher PRE-turbo, by several hundred degrees.

 

Cummins recommends going post turbo. If the thermocouple ever comes apart it will cause "catastrophic turbine failure". They also claim 700-900 degrees as a safe limit.

 

pre turbo is aprox. 100 degrees per 10 pounds of boost hotter than post turbo. The hot side of the turbo transfers the heat into energy to make boost on the cold side.

 

As often as that happens (never heard of a single case personally) I'd rather risk "catastrophic turbine failure" rather than experience catastrophic piston failure because my temp reading wasn't as accurate. Besides, that's just a good excuse to buy a new turbo!

 

Specifically, where did these post turbo location and limit recommendations come from ?

 

In SEVERAL years of reading posts on SEVERAL diesel forums on almost a DAILY basis I've never come across a post of a EGT probe failure! Or ever heard of one.Until the 3rd generation group NEVER heard or told to ever put a EGT probe post turbo.Always PRE.for a ACCURATE real world reading.

 

OMG!! MY EGT PROBE JUST GRENADED AND TOOK OUT THE TURBO!!!!!









































just kidding.

seriously, though... I put it pre-turbo because that's where all the long-time hard-core drag racers and sled pullers put it. I figure who should know better than the guys running 1600+ degrees on a regular basis.. who live right on the edge of blowing a hole through their piston any time.. who sacrifice years of salary just to play because it is their business and/or life... and may have seen 3 pistons with holes in them but never a failed thermocouple.

 

Well done Jeepdude, You get a gold star

 

take a look through most diesel engine college text books, and they say the pyrometer probe should be post turbo 12"... i did when i read that, and i told my instructor at school that is total bs... [and he wrote the book too...]

 

1250/1300 degrees or so is what truckers told me the REDLINE of EGT's was and that was YEARS ago when I inquired about my 1993 W250.Long before I had a computer or knew about forums.Now if THEY were running POST were did that temp figure come from? It sure wasn't a POST reading now was it?

 

if those figures were post turbo them they were about 4-600 degrees or more in the red

 

them truck engines also have better cooling than our engines.. with the wet liners, the cylinders get cooled better, and most [if not all] have steel crown atriculated pistons [or some now have all steel pistions, no aluminum trunk] and most have firerings from the factory... but still 1230-1300 post is very hot...

at school the one engine in the lab had a pyro on the "dash" but it was not hooked up/not functional, but it was marked 950° max temp [was a mack gauge, on a cummins n14 engine]

 

However and whatever.I'll say again until I got a 3rd generation I never read or heard of pyro POST TURBO.