Individual EGT readings

swank

swank

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Joined
Oct 15, 2006
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Hey all,

Just wondering if anyone has put six EGT probes in and if so, what the readings were? I am looking for data to either back up what I'm seeing, or data that says what I'm seeing is way off. Please let me know either through pm or here.

Thanks!
Dave
 
data logger vid, goofing around on the dyno:

[ame="http://s30.photobucket.com/albums/c338/texashwhu/?action=view&current=IMG_0894.mp4"]IMG_0894.mp4 video by texashwhu - Photobucket[/ame]
 
swank said:
Hey all,

Just wondering if anyone has put six EGT probes in and if so, what the readings were? I am looking for data to either back up what I'm seeing, or data that says what I'm seeing is way off. Please let me know either through pm or here.

Thanks!
Dave
Click to expand...

Keep in mind that using pyros at all 6 cyls. is better used for just balancing the cyls. rather than trying to get an accurate exh. temp. reading. They are not accurate because the probe spends more time with nothing going past it than it does trying to read exh. temperature. Of the 720 degrees of crankshaft rotation it takes to complete a 4-stroke cycle, less than 200 degrees of that is spent expelling exhaust gas past any individual pyro probe exiting the cyl. head.
 
I have 6 in mine during a run they will be all with in 50 degrees of each other. At idle they are I would say with in 10 degrees of each other
 
Thanks Jeremy! Have you heard of anyone having a range from 150 on 6, increasing to 300 on 1 at idle?
 
what is the reading at idle? I see 100 or so difference on all 6 of mine.
 
Dave, good to see you on here...

I think I had maybe 100 degrees total difference in my readings between cylinders.

Did you get to run at the salt flats this weekend? How did it go?

Jesse
 
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Hey Jesse! We are running this coming weekend. Leaving day after tomorrow. Getting on dyno tonight to try and get everything squared away with fueling and timing (with our awesome adjustable timing gear...).

Smokem, it does sound like it's idling quite well. Just getting going with it though. Barely broke in at this point.
 
If you have a cylinder dropping way down on EGT while idling, I would suspect compression or your not injecting cleanly.

I had an engine that one of the cylinders would be about 150-200 low while idling, as soon as you would load the engine, it would start to heat up. Upon tear down there were marks in the cylinder.
 
I will add that it seems like a pretty linear increase from the rear of the engine to the front.
 
zstroken said:
If you have a cylinder dropping way down on EGT while idling, I would suspect compression or your not injecting cleanly.

I had an engine that one of the cylinders would be about 150-200 low while idling, as soon as you would load the engine, it would start to heat up. Upon tear down there were marks in the cylinder.
Click to expand...

Hmmmm. Ok, will keep this in mind. Thank you.
 
swank said:
Thanks Jeremy! Have you heard of anyone having a range from 150 on 6, increasing to 300 on 1 at idle?
Click to expand...

No, switch the probes in the manifold and see if it follows, leave them plugged into the data system. If it does i would think the probe is bad or the data system is off. What data system is it and what probes are you using and have you calibrated the system? There should be no reason that the engine is hotter in the back and gets cooler as you come forward on the engine or the other way around. Mine idles at around 200 degrees and is set at around 1600-1650 down the track. I do have an erratic probe that will jump around but settles back down through out a run and it doesnt do it every run.
 
mhuggler said:
Keep in mind that using pyros at all 6 cyls. is better used for just balancing the cyls. rather than trying to get an accurate exh. temp. reading. They are not accurate because the probe spends more time with nothing going past it than it does trying to read exh. temperature. Of the 720 degrees of crankshaft rotation it takes to complete a 4-stroke cycle, less than 200 degrees of that is spent expelling exhaust gas past any individual pyro probe exiting the cyl. head.
Click to expand...

If you are using something like an inconel or stainless sheathed thermocouple, there is enough hysteresis in the heating and cooling of the sheath that this is often negligible. What you're describing is only true if you use very fine TC wire, unsheathed, and you had a datalogger that was sampling damn fast, and you use no oversampling or averaging.

Knowing the instantaneous EGT in any given cylinder isn't something most folks here would be able to use in a practical manner.

Oh and BTW, do what Disturbed says about checking your probes and/or instrumentation. If you're getting data that looks like BS.....check it and re-check it.

A guy at work just bought an infrared thermal camera......if you truly have a 300F delta, you would see that immediately, if you know someone who has one.
 
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Well, got some tuning done tonight on the dyno. Got 150hp and 200tq with some wastegate tuning and some timing. I haven't had a chance to look too deep at the data, but the delta seemed to go down as the timing came up. I will have to post some screenshots of the system, the electrical engineering student built the system with National Instruments brains and sensors from various sources (Omega, Automation Direct, PCB Electronics). It's all programmed in LabView. I don't know if he has calibrated the system in ice water yet, but he was talking about taking all the probes out and doing that. We shall see...
 
If he used the same formula for the base line on each channel then there might be the problem. The variance in the probes could cause the problem. You dont need to use ice water to calibrate the probes, just use room temp. Depending on how he wrote the program he may need a different formula for each channel to make them read right depending on how good the probes are. My probed are $150 each.
 
I've never seen TCs be off that far and still work.

Make sure you use ungrounded junction TCs if they are sheathed. That way you don't have some stray current or something like that hosing up the D/A board.
 
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