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Author Topic: High calculated EGTs at part throttle  (Read 5817 times)
SB_GLI
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« on: August 06, 2014, 08:32:40 AM »

I am trying to get a grasp on different methods to lower egts.  My current issue is high calculated EGTs, especially at part throttle.  EGTs will rise and BTS fueling overtakes during a part throttle pull with load ranges in the 130-150 area. 

On one particular pull (will provide the log file and a screen shots later) boost is around 8-10 psi from 2,500 -4,000 rpms and ignition advance is in the 1-3 degrees range during that time.   Calculated EGTs rise up to 950+ degrees during this time.

I understand that ignition timing has a lot to do with EGTs and therefore I have tried to + and - timing.  When I retard timing, the smoothness of part throttle was better than ever, but egts seemed to increase more.  When I advance timing, part throttle is not as smooth.. I have not yet take logs of the timing advance to evaluate what is going on with the EGTs.

I understand that this may be a question with too many variables to answer, but how accurate are these calculated EGTs?  I assume they would be affected if the exhaust was open a bit more than what it would be stock (with a higher flowing manifold and a 3" exhuast).

Car in question is 1.8t AWP with a Frankenturbo and 3" catted exhaust.  I disabled my w/m for the time being to dial in my non w/m tune.  With w/m, I don't think EGTs were an issue as I never felt BTS kicking in before.

Logs to come.

Let's discuss.
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ddillenger
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« Reply #1 on: August 06, 2014, 12:56:47 PM »

Do you still have a rear o2 sensor?
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SB_GLI
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« Reply #2 on: August 06, 2014, 01:04:17 PM »

Do you still have a rear o2 sensor?

Yes.  This might play into the equation.... I have a 42dd spacer on it though to keep it from throwing the cat code.
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turdburglar44
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« Reply #3 on: August 06, 2014, 01:39:40 PM »

I've heard that you can use o2 voltage as a rough estimate for egt. Maybe from there do a little t1/p1 = t2/p2 to find exhaust manifold temp.

Maybe I'm crazy but I am certain of these ways to lower egts.

- lower AFR will cause more evaporative cooling. Exhaust will have the same enthalpy but lower temp. (E85, meth and water injection fall into this category)
- lower boost. Less charge, less heat content, less exhaust manifold pressure (I know obvious).
- advance timing as far as possible. Charge spends more time in cylinder and the cylinder absorbs more of the heat.
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Tuning is the easy part...
ddillenger
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« Reply #4 on: August 06, 2014, 02:06:07 PM »

Yes.  This might play into the equation.... I have a 42dd spacer on it though to keep it from throwing the cat code.

Put the rear o2 back in place, and relog. See what happens.
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SB_GLI
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« Reply #5 on: August 06, 2014, 04:00:19 PM »

came to upload some screen shots and a log but getting an error doing so. admins contacted.
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ddillenger
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« Reply #6 on: August 06, 2014, 04:26:51 PM »

came to upload some screen shots and a log but getting an error doing so. admins contacted.

Yeah, I think the site has hit the limit....Bigger deal than you know with Tony being MIA.
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SB_GLI
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« Reply #7 on: August 06, 2014, 05:19:47 PM »

Yeah, I think the site has hit the limit....Bigger deal than you know with Tony being MIA.

I figured that could be the case.
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ddillenger
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« Reply #8 on: August 06, 2014, 05:42:15 PM »

I just spent the last hour deleting all of the checksum requests and the unviewed, undownloaded tuned files. We should be good for a while now. Upload away!
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SB_GLI
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« Reply #9 on: August 06, 2014, 06:22:18 PM »

I suppose it doesn't help that my log file is 5mb.

I think I might have torque intervention right after the gear change.  Notice the ignition advance on the first part throttle pull, and after the gear change there's almost no advance and egts go way up and bts kicks in.
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