EGT

Roachie, I have an EG/pyro fitted, the probe is fitted about 3" below the turbo to exhaust flange. I used an Issspro, colour coded one, but am not real happy with the reflections from the concave glass. It certainly helps to know what the EGT is and take corrective action if needed. Hope this helps.

The exhaust manifold is the ONLY place to put the probe, that is worth anything as far as being worthwhile measuring egt's.

grease on the drill bit will catch the nasties.

Mine is just after the turbo on the exhaust.

Roachie, those sort of temps would have to be below the turbo.

Hi Gents,

Having seen my name mentioned in dispatches, I thought I'd put in two cents worth...

My recommendation, based on quite a lot of reading and research, is that the exhaust manifold (turbo inlet) is by far the best place to measure EGT. As the exhaust gases pass through the exhaust turbine, they lose pressure and temperature - this is the energy that drives the compressor wheel. The problem with measuring EGT at the turbo outlet is that it is difficult to know how much the temperature is reduced through the turbo. Several authorities quote temperatures between 100 and 200 Deg C temperature drop. That is, if you're reading 600 C after the turbo, the inlet temperature could be as high as 800 C! And that is much too high!

Most experts recommend maximum inlet temps of between 704 C [1300 F] and 732 C [1350 F], with 720 C being a common recommendation in between.

The parts that suffer most commonly from excessive EGT include the exhaust turbine housing [erosion and cracking of the iron], wastegate valve and seat [erosion] and the exhaust turbine blade tips [erosion or just plain melting]. All these parts 'see' the inlet temperature, not the cooler outlet temperature.

While it might be possible to measure and correlate inlet and outlet EGTs at full load for a particular model engine, I still believe there are too many variables to form a reliable estimate of turbo temperature drop. Just the normal manufacturing variance in boost pressures from engine to engine could lead to EGT differences of many tens of degrees between otherwise identical engines. And once you start talking injection pump tuning/re-chipping, it all changes again.

My recommendation is, wherever possible, unbolt the turbo from the exhaust manifold and cover it's inlet with cardboard or plastic. Then drill and tap the manifold and carefully remove all swarf [a vacuum cleaner and magnetic screwdriver can both help here]. Now replace the turbo with a new gasket and complete the sensor and indicator fitting.

Now on some engines, it just may not be feasible to fit the sensor upstream of the turbo. In these cases, I'd say that some indication is far better than none at all, so an outlet EGT is still useful - just stick to a conservative maximum like, say, 500-550 C before backing-off the throttle or changing down a gear and giving your engine a bit of a break.

For more information please have a look at the Information Sheet downloadable from my website or have a read of the excellent article on EGT on the Gale banks Engineering site in the USA: http://www.bankspower.com/Tech_whyegt.cfm