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Old 11-08-2006, 11:18 PM   #1
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Default EGT: Placement, probe source, limits, and even necessary?

My LMA logs EGT and I already have the wires so I was thinking about logging it. Few questions.

I see that #4 runner is the hottest, but near the collector would work also (preferable?).

Max temps? I've heard over 1600F is bad, but anyone have a more accurate/realistic number?

I found this quickly searching. Seems cheap. Anyone here sell probes? Any Type K sensor. http://www.aircraftspruce.com/catalo.../micro5egt.php

Lastly, is monitoring EGTs even necessary? Seems like with accurate AFR readings, EGT is kinda, uh "outdated" I guess. (??) Seems to be more of a "safety" thing..
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Old 11-09-2006, 09:57 AM   #2
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IMO egts are nice to know for fine tuning w/o a dyno. One more piece of data to reference when going through logs or tuning.

For a single probe, preferrable location is right at the turbine inlet so you can see a cumulative temp. That should show your peak temp since that's the convergence point of all gas and the point of resistance to exhaust being forced into the turbine housing. You could also place bungs at each runner to check the individual tuning of each cyldiner. Then make four dyno/DL runs, moving the probe between each run.

As far as peak EGTs, there's numerous arguments to what is too high. Lots of guys see peaks right at 1600f measured at the turbine intake and don't have problems.
mnet EGT post 1
from this thread
and another one

That looks like the going rate to me for a K sensor.

IMO the EGT shows more detail about the combustion- vs. the AFR showing detail on the product of the combustion. Make sense? IOW - the AFR would never show a tune that was over fueled and/or under advanced IF "all" the fuel was being burnt- even though it was being burnt outside of the cylinder- in the manifold. Being able to determine that with an excessive EGT is having the ability to recover available power. For me, I uncovered an over advance that was being knock prevented by over fueling (under 100kpa). High EGTs where the tip off something was wrong. -rob
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Old 11-09-2006, 12:31 PM   #3
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Quote:
Originally Posted by m2cupcar View Post
One more piece of data to reference
Never hurts!

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Originally Posted by m2cupcar View Post
For a single probe, preferrable location is right at the turbine inlet so you can see a cumulative temp. That should show your peak temp since that's the convergence point of all gas and the point of resistance to exhaust being forced into the turbine housing. You could also place bungs at each runner to check the individual tuning of each cyldiner. Then make four dyno/DL runs, moving the probe between each run.
M2, do you think all 4 would be worth it? I don't have the coolant reroute. It would be interesting to see the difference once temps start climbing. Although I must admit I'd like to just insert one probe, possibly welded in, so the maintence is zero. One less thing to think about leaking. The plugs ever loosen/leak/?

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As far as peak EGTs, there's numerous arguments to what is too high. Lots of guys see peaks right at 1600f measured at the turbine intake and don't have problems.
That's the word on the streetz too.

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IMO the EGT shows more detail about the combustion- vs. the AFR showing detail on the product of the combustion. Make sense? IOW - the AFR would never show a tune that was over fueled and/or under advanced IF "all" the fuel was being burnt- even though it was being burnt outside of the cylinder- in the manifold. Being able to determine that with an excessive EGT is having the ability to recover available power. For me, I uncovered an over advance that was being knock prevented by over fueling (under 100kpa). High EGTs where the tip off something was wrong. -rob
That's new info for me, word! Gonna do it. Thanks rob.
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Old 11-09-2006, 12:34 PM   #4
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Braineack, Wideopen, whoever I'm forgetting,

You guys sell probes?
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Old 11-09-2006, 12:56 PM   #5
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Don't weld it in. It will fail eventually and need to be replaced. I have mine in the same position as IntrnlStorm on one of the referenced threads.

The one that came with my Zeitronix was open and used to catch little pieces of carbon and shoot way high. Then the gases finally eroded it. I bought a GReddy replacement and it has been fine, albeit slightly slower due to the tip being enclosed(milliseconds)
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Old 11-09-2006, 01:02 PM   #6
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I don't sell probes but will have an Autometer EGT gauge and probe setup for sale very soon for around $75. Also, I tapped about 2 inches away from the head on cylinder 4 when I had my Miata.
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Old 11-09-2006, 02:26 PM   #7
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I only have one location at the collector, about 1" from the turbine housing flange. There's too many other things to do before worrying about individual cylinder data. I have a coolant reroute by default anyway. No reports of a hot number 4 from the fwd crowd on the FE3 either.

I'm using the autometer egt/probe and it's worked great. The only hiccup was a shared ground that was causing the egt gauge to flake out. Provided a "solo" ground and it has been perfect ever since. I'm using the clamp to hold it in on an odd shaped collector and it works fine.
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Old 11-09-2006, 03:30 PM   #8
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Don't weld it in. It will fail eventually and need to be replaced.
Amazing. The stuff I don't think about
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Old 11-09-2006, 03:42 PM   #9
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There's too many other things to do before worrying about individual cylinder data...No reports of a hot number 4 from the fwd crowd on the FE3 either.
Yeah, who am I kidding? You're more right than you even know. Thanks for the links, that's great info!

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Originally Posted by Wideopentuning View Post
I don't sell probes but will have an Autometer EGT gauge and probe setup for sale very soon for around $75.
Thanks. I have the LMA and laptop for the car. With Logworks2 I'm pretty sure I can read realtime.

Just need the probe.

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Old 11-09-2006, 04:09 PM   #10
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Quote:
Originally Posted by UofACATS View Post
Amazing. The stuff I don't think about
Last I checked though, most EGTs are setup best with weld-in bungs. Then you can simply unscrew the egt probe.

Thats how my autometer one is setup on my civic.

From everything I've looked into and been told... the ideal setup is one per cylinder... 2 inches from the head. If not... pick the hotest. On the civic that is cyl3, so I have it 2 inches from the head there... then i can monitor the hottest conditions that will come out of the motor.

I'll be running one on my miotta project... just unsure of where... it'll have dual feed rail and coolant reroute... so possibly just in the collector for an overall look.
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Old 11-09-2006, 04:38 PM   #11
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I would be interested in your EGT gauge.
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Old 11-09-2006, 05:37 PM   #12
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I was going to weld a bung, but several recommended the clamp and ceramic gasket and it's worked. Saved me the work of removing the header. I think the location depends on what you're after. Agreed a probe per cylinder is ideal. I think knowing the TIT gives a "big picture" of overall engine tune. - rob
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