EGT and Turbo Probe location/s

**gavinwibrow** · 11th December 2018, 02:41 PM

So, given there are a couple of "preferred" locations to fit the EGT probe, does anyone have any definitive information on the max short term and cruising temps recommended to (i) save your donk and (ii) for longevity?

My D2 TD5 has the probe about an inch back towards the engine from where the exhaust manifold meets the turbo gear. I've always assumed a cruising max of 600 C, and preferably under 550 C? for this location.

I also have a desire to learn the appropriate max temps for those who place their probes in the alternative (post turbo?) location, and for which I hear anecdotally that equivalent temp readings should be about 200 C lower?

**rangieman** · 11th December 2018, 05:10 PM

My probe is about the same position as yours .
I get about 350 C cruising @ 100 ks i can get to 630 C max with the camper on at about 1300 kg`s wide open throttle climbing in 4th gear at about 90 ks .
750 C seems to be the magic back off point if your remapped or a Salt&Vinegar box

**oka374** · 11th December 2018, 07:19 PM

As aluminium starts to melt at 660 degrees C it might be wise to limit EGT's pre turbo to 650C as a maximum and then only for short periods like when changing gears or it might get expensive down the track.

**rangieman** · 11th December 2018, 08:52 PM

Originally Posted by oka374

As aluminium starts to melt at 660 degrees C it might be wise to limit EGT's pre turbo to 650C as a maximum and then only for short periods like when changing gears or it might get expensive down the track.

We are talking exhaust gas temp not a melting pot

Mine is standard tune with d egr , d cat , d main muffler larger intercooler and a hybrid turbo 630c is nothing

Like i said if you see 750c back off

**steveG** · 11th December 2018, 09:01 PM

Originally Posted by oka374

As aluminium starts to melt at 660 degrees C it might be wise to limit EGT's pre turbo to 650C as a maximum and then only for short periods like when changing gears or it might get expensive down the track.

Not sure which aluminum part you're concerned about melting - but unless you're running an aluminum exhaust manifold or turbine housing I don't think it's relevant. The head, block and pistons never reach anything near EGT temps.

Factory max (sustained) EGT on an Isuzu 4bd1t engine is 750degC PRE turbo.
Given thats an 80's vintage truck engine I see no reason why it shouldn't be a reasonable figure to work to for a modern turbo engine in the absence of a specific manufacturers limit.

I've personally run sustained ~700degC PRE turbo for hours on end on my 1981 4bd1 NA engine. Not unusual for it to hit 750C for brief periods.
Had the head off recently to change the head gasket (which was likely the original from 1981) and no signs of heat related damage/stress.

Steve.

**oka374** · 12th December 2018, 06:11 PM

Each to his own, as many engines have alloy internal components these days it might pay to be prudent, I'll stick to 650 maximum for peace of mind.

**Blknight.aus** · 12th December 2018, 06:27 PM

Strap a K probe to the manifold and monitor that with a meter,

keep that one under 650 when under sustained loads and reference your post turbo gauge. (remember it takes a little bit for the manifold temps to change.

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