Thread: Pyrometer in a TD5 defender

A/ don't know - still to do it...
- it requires turbo/manifold removal to drill and tap fitting (well to clean the swarf out anyhow!)
- plus a location to mount the gauge.
B/ Think it should go before turbo, so it measures EGT from motor not after turbo.
C/ I have a VDO unit, there are other makes too.
D/ I should have done this already, as this will tell you how well(or not) your motor tune is.

Leo109 is your man.
If he doesnt see this send him a PM.
Andrew

DiscoWhite has one in his D90.

I will watch with interest what Leo109 has to say!!!

LRH

and this is Ian's/Leo 109's website. http://www.thermoguard.com.au/

Originally Posted by Sandtoyz

A/ don't know - still to do it...
- it requires turbo/manifold removal to drill and tap fitting (well to clean the swarf out anyhow!)
- plus a location to mount the gauge.
B/ Think it should go before turbo, so it measures EGT from motor not after turbo.
C/ I have a VDO unit, there are other makes too.
D/ I should have done this already, as this will tell you how well(or not) your motor tune is.

I know this has been discussed before and I found this to be quite interesting!

Whilst preparing to install all my extras I was looking at the manifold and the job ahead! Debating the in manifold or in exhaust mounting option.
So I went to a few manufacturers sites and found this...

VDO states in its fitting instructions (I downloaded them the other day) that the EGT/Pyro sensor is to be fitted 100mm downstream from the turbo.

Hmmmmm....

Makes it easy I think!

Originally Posted by tombraider

<snip>
VDO states in its fitting instructions (I downloaded them the other day) that the EGT/Pyro sensor is to be fitted 100mm downstream from the turbo.

Hmmmmm....

Makes it easy I think!

and not as accurate as upstream. You are looking at at least 200*C lower temps there.
just my 0.02c worth.

from Ian's site,

There is a consensus of international sources which suggest that sustained gas temperatures in excess of 720 ºC (~1330 ºF) upstream of a diesel turbocharger will result in progressive and irreversible damage to components in contact with the gas. These may include piston crowns, exhaust valves/seats, manifold and, most commonly in the case of turbo-charged engines, the turbo-charger housing, exhaust turbine and waste gate.
A pre-turbo measurement is an 'absolute' measurement - that is, it is the actual temperature to which the turbine blade tips, the wastegate and the turbine housing are being subjected. The temperature drop across the exhaust gas turbine is difficult to quantify. It will vary with load, speed and will be different for every engine design. A post-turbo measurement requires assuming a 'worst case' temperature drop across the turbine and subtracting that from 720 ºC to arrive at a suitable limit for downstream EGT.
I have measured almost 200 ºC difference between turbo inlet and outlet temperatures on my Land Rover 2.5L 300Tdi under full load conditions, so I recommend 520 ºC (~970 ºF) downstream as a safe limit for such installations. This will be quite safe in the vast majority of cases but it is also probably overly conservative in some cases, especially large capacity, relatively low-boost (i.e. <10 psig) standard engines.
top of page

and from the Banks Power website

What is the best location for the exhaust gas temperature probe on a turbo-diesel?
This question is tougher to answer than you might think. There are two ways to measure exhaust gas temperature on a diesel engine: before the turbo (turbine inlet temperature); and after the turbo (turbine outlet temperature). When reasonably convenient, we recommend measuring the turbine inlet temperature, because this is the hottest—and most meaningful—temperature when evaluating the engine's performance. But when there's not a convenient place to put a probe in the turbine inlet side of the exhaust, the alternative is to mount the probe after the turbocharger, measuring the turbine outlet temperature. But this also presents a problem. The outlet of the turbo on the Duramax engine, for example, is shaped awkwardly, and the factory turbine outlet pipe is a very non-concentric shape to accommodate the outlet, so once again, there is not a good place to install a probe until about two feet after the outlet of the turbo. By going that far downstream, the integrity of the measurement is sacrificed.
Perhaps the best recommendation is to drill and tap a hole in one of the exhaust manifolds, and install a threaded pyrometer probe in there. Just be VERY CAREFUL about not getting any metal chips in the manifold, which would cause damage to the turbocharger. About the only way to be sure of this is to pull the manifold off of the vehicle to do the drilling and tapping.

Can failure of the exhaust gas temperature probe damage the turbocharger?
This is a highly debated issue. Some of the sentiments that surround this question date back quite far. Before diesel engines became widely popular in pickup trucks, the main use for diesels was in the long-haul trucking industry. Years ago, when truckers began to use pyrometers on their engines, the most logical place to position the probe was in the exhaust manifold ahead of the turbocharger, because this was the hottest portion of the exhaust stream. But the earliest probes that were used had exposed junctions, and the weakness of this design would sometimes fatigue and fail under the high heat conditions. A failed probe would inevitably cause expensive damage to the turbocharger. The solution to this problem was to move the thermocouple downstream of the turbocharger, thus avoiding the potential damage to the spinning turbine wheel. Knowing that the temperature would be lower in that location, it was expected that the operator would compensate for the difference by an appropriate amount. Today, the thermocouple probes that are used are commonly sheathed in a stainless steel shell that is impervious to the type of failure that an exposed junction thermocouple might experience. This makes it safe to install upstream of the turbocharger. At Banks, we typically prefer to mount the thermocouple upstream of the turbo, but this is not always convenient. In the case of the Ford Power Stroke, we opted to provide a bung in the turbine outlet pipe rather than having the customer go through the difficulty of drilling and installing a probe in a location that is hard to access. Our testing shows that the maximum allowable turbine inlet temperature of 1350 degrees is equivalent to 1050 degrees on the turbine outlet side, so that is our recommended maximum temperature when measuring in that location. The temperature differential may be broader at lower temperature ranges, but the temp that we are most concerned about is at full power.

The blanking (EGR) plate looks similar to what's on this picture



so could it be a good place for gas temperature probe?