feellogoboss

I came across this info and thought it would be worth sharing and shows the difference between pre and post turbo EGTS and the inaccuracies associated with post turbo EGT's. Looks like if you subscribe to a post turbo value of 550c with the probe 100mm down the dump pipe you could be hitting nearly 800c pre turbo in the manifold.
All from a user on Lcool.
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I thought you may be interested in some data generated by my factory turbo diesel engine recently.
I had recently fitted a new Beaudsesert 76mm 304 stainless steel exhaust , which conveniently had a thermocouple port tapped into the downpipe. I already have a thermocouple in the turbine inlet about 3cm upstream, so this was an opportunity to test the delta across the turbo.
I borrowed a Fluke Data Logger and some calibrated Westach pyrometer probes from my mates in the R&D Lab, where I worked before retiring, and set out with the caravan in tow.
My route was through central west NSW, with an all up GCM of 6,175kg (weighbridge) during the last 4 weeks.
The truck is a 2001 HDJ100 (A442 Auto) and previously I had a Safari chip fitted. The truck performed very well with the chip (and standard exhaust), but the fuel consumption when towing was in the 14 to 15L/100km range and I wanted to try and improve that figure.
Hence the 76mm exhaust.
The Beaudesert stainless exhaust is a beautiful piece of engineering, quick and easy to fit, because it aligns perfectly during installation, and from my perspective is supported by 1st class customer service (but that's another story).
Fuel economy over this trip with the chip and the new exhaust averaged 13.8L/100Km, over 4,629 km. I'm happy with that as I was towing for 3,096 km.
The exhaust gas temps were downloaded from the datalogger and I have chosen the following data to present here as it represents what I was seeing during the greater bulk of the trip on the western plains. That is, there were higher figures for turbine inlet (max 720 C ) and this was associated with climbing over the Blue Mountains, west of Sydney, both travelling west and back east again.
The data:

Set up the probes during last weekend and carried out some preliminary testing early in the week.
Used another datalogger this time. Managed to get one with 20 channels for a few days. Sadly it had to go back as it was committed elsewhere today.
The voltage feed from the pressure sensor is very blocky under most operating conditions so I have spent far too much time with the interpolation algorithm on the data logger, but that's behind me now.
The results are below for the drive last Wednesday, which was fairly warm.
No caravan this time, with aggregate mass down on last results.
The thermistor probes in the intercooler feeds were calibrated last year, and the psig information is calculated as all the feed signals are treated in the information database metrically.
As I am chasing better fuel economy, I am not sure yet whether I will fit a larger front intercooler.
It seems the OE Intercooler is effective (to a degree) at normal speeds, but I suspect a larger unit that lowers charge air temperatures further will also increase (relatively) the fuel consumption, due to increased oxygen available for combustion.
As a side issue, I have also been looking at, and trying to find, if there is any measureable difference in fuel economy between Diesel fuel at 48 Cetane Index, and the so called Premium Diesel fuels with Cetane Index reported at 52-53.
Logic tells me the Premium Diesel will have lower density and therefore slightly worse fuel economy, but maybe that should be the subject of a separate post for discussion.
Anyway, for your interest:

So you guys hitting 550c post turbo with your probe 100mm down the dump pipe could potentially be seeing near on 800c pre turbo.