EGT probe position

[kbareham]

Chaps

Some advice needed !

Just got my Zeitronix wideband Lambda/datalogger and sensors. I'm not sure where best to position the EGT probe ( K type thermocouple).
I still have the stock twins, and I was thinking of placing the EGT probe where the stock narrowband lambda sensor fits, since the Zeitronix has a simulated narrowband output that I can feed into the PFC. But then this is right by the ports and will be very hot (too hot???). I have successfully done this on non turbo boingers previously.

Any other ideas?


Keith

[maximtaylor]

I think any form of EGT on a turbo rotary is not going to have a very long life tbh.

Fit it, tune it and then remove it, or just let it wear out and ignore the readings ;)

I'd be tempted by the narrowband O2 sensor location, because it does save on butchering the exhaust.

You could put it further down the system, which would make the sensor last longer. The temp readings you got would be lower, but you would still get indication of high / low/ normal temps as you would further up the system, albeit all the values would be lower.

[kbareham]

Thanks Max.
I think I'll put it someway downstream, around where I am going to put the lambda probe. I'll have to weld in the fitting for the lambda anyway, so a little more won't hurt. And if the probe fails, it can just stay in there to block the hole up.

Keith

[rx7veilside]

in the downpipe near lambda probe shd be fine i had a defi one in my old scooby in the uppipe pre turbo and it handled the heat okay on cruise was about 8-900 deg i think..wld be interesting to know what egt is good on a rotary ie at which point to start getting concerned

[maximtaylor]

If you put the probe in, drive the car and the probe fails, it's too hot!!!

Seriously though, if the needle goes past the 900 celsius mark, I would keep an eye on it. But it can get this high on a long duration pull.

wld be interesting to know what egt is good on a rotary ie at which point to start getting concerned

[rx7veilside]

cant remember exact but used to see about 950 on short bursts but like i say probe was pre turbo in the up-pipe so well hot and no airflow

[Fish]

The readings pre-turbo should be circa 80-100c higher than post turbo. Best position is closest to the exhaust ports, but this is a pain on an FD.

Fish

[kbareham]

Hmm, maybe I'll try it up close to the ports, and if it fails it's only the cost of a sensor. I should get some time over the next few weekends to get it all installed and see what happens.

Keith

[kbareham]

Chaps
Finally got time to look at this again today. I made up an adapter to take the EGT thermocouple in the original lambda sensor position. I welded the new lambda boss into the mid pipe to take the wideband lambda, but can I get the exhaust to stop leaking? not a chance!
It is leaking slightly where the midpipe meets the downpipe. It always has leaked slightly, but now I don't want any leaks causing errors when reading from the newly positioned sensor. I have the stock downpipe and an unsilenced midpipe. The flanges seem to be reasonably straight, but since the midpipe is a larger diameter than the downpipe, the gaskets are not seating well. What does everyone else use? Stock gaskets? I have larger diameter ones to match the mid pipe.
I am toying with the idea of maiking a copper gasket tomorrow to see whether that helps.

Keith

[maximtaylor]

Could always get an aftermarket downpipe to match in size? :)

More money spending!!

[kbareham]

Max
The obvious solution, but I have a T04 and manifold in the workshop. I don't want to buy things that are ultimately no use - we have all done that before and doubled the budget (haven't we???). So its no downpipe for now...

But with a combination of fabricating a copper gasket, the large diameter gasket and lots of exhaust paste, it is now gas tight.

So once I can breath in the workshop again after starting it up, I'll get the lambda cable in and see how it goes from there.

Keith