EGT sensor placement
 

So I picked up an egt guage/sensor from a buddy for cheap last week. Now I thinking where is a good spot for it, IIRC cylinder #4 runs the hottest so maybe putting it on that runner would be best? Or should it go after the turbo? Do I have to have a good heatsink or anything? Or ca I just get a bung welded on and toss her in? I know I could find all this if I searched but I'm bored, its hot outside and I'm not going to the grand prix til later. Also this is an autometer unit, how are they for accuracy? Thanks guys.



-Dean

EGT should be before the turbo near the #4 runner in the collector. Should normally just be a 1/8" NPT fitting with a ferrule to hold the probe. No heat sink.

Thanks oldtop :)

raising the dead..

but when installing the EGT probe, after tapping the manifold, do you deal it with normal teflon tape? or use some high temp RTV?

I installed mine with nothing. The tapered pipe thread seals up fine.

+1 thread it in and go.

Thanks!

EGT Probe placement
 

Raising a really old thread, but I have a really old turbo setup. 1st installed in 2004.

My Zeitronix EGT probe has failed after 50k kilometers. No complaints. Gave me valuable data for seat of the pants tuning.

The existing probe is on the underside of the AVO collector before the turbo, inline with no.3 cylinder runner. A real SOB to get at from under the car. It does not want to come out and I'm worried about shearing it off with too much torque applied. Could end up with a jammed up thread/hole that would be very difficult to repair.

Has anyone put the EGT probe into the top of the collector before the turbo inlet?

I'm happy to drill & tap the manifold there. Don't know how thick the collector is but the underside drill & tap worked fine. I would need to modify the AVO heatshied to clear the probe.

Is there a thread compound that will stop the probe locking into the thread for subsequent removal?

I have seen a couple of people install EGT probes in the top-side of the FM cast manifold at the collector. That said, I'm surprised to see interest in EGT still alive. Personally, I never had much use for it after the advent of cheap wideband O2 sensors.


Permatex Nickel anti-seize compound is allegedly good to 2400°F. Not sure what distributors there are in .au, but I'm sure some equivalent must exist.

Thanks for the quick reply.

I use the egt in conjunction with the WBO2 sensor through the Zeitronix ZT2 for data logging. It allerted me to excessive spark retard even with good afr readings. It was also especially helpful to locate part throttle lean tip in.

I guess it is something I use that others may not see as necessary. My setup is very old school with a 5th injector and factory ecu so no control of the primary injectors.

I will proceed with the EGT probe in the top of the collector.

EGT is a great tool in addition to a wideband, not as substitute for one. In the same way, a wideband doesn't fully remove the need for an EGT solution. Your wideband is the best tool for measuring a/f ratio. EGT is not the best indicator of a/f ratio, but it can tell you if you're not running enough timing or too much boost. EGT thermocouples are also much less fragile than LSU sensors and can be placed immediately before or after turbos.

I grew up thinking about EGT in terms of its use in aircraft. As a student pilot flying carbureted piston-engine airplanes, you're taught to set the mixture control for full rich on takeoff, and then eyeball the EGT gauge while leaning out the mixture once you're in cruise.

As a measure of timing, I guess that there's still some validity here. It just seems like far too vague a relationship to me. Even without a dyno, you can optimize timing much more precisely by operating the engine at a constant load / speed / AFR, and seeking minimum injector duration.

A 4 channel EGT setup is still ~$250 cheaper than a 4 channel wideband setup. And I KNOW that the temps in any reasonable length turbo manifold is too high for extended use of the LSU units.