I'm getting some high numbers since I got the gauge..
1100s idle
13-1400s cruise
1600-1700+ at wot
stock engine & exhaust....It's pretty easy to see 1700+ at wot...it seems like the pcm supplies the egt reading from a pretty inaccurate source, I couldn't possibly be hitting 1700+ so easily....
anyone else seeing this or have any more feedback on the high reading?
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Yes, I have seen it as high as 1750 at WOT @ top of third. That is on an uphill slope. If I do the same on the downhill side it is in the low 1600's. I am running a 50 trim and a 3" TBE, too.
I think you'd be surprised at how hot the EGT's get on these cars. I have an actual EGT sensor and I believe it gets over 1650 deg even with my 50 trim. I'll have to check my notes.
I think you'd be surprised at how hot the EGT's get on these cars. I have an actual EGT sensor and I believe it gets over 1650 deg even with my 50 trim. I'll have to check my notes.
Todd
I'm not surprised at getting close to 1700, I know it's not hard to do, but 1700+ is too hot to hold, and according to this gauge, 1700 comes on well before redline and holds that high....this gauge seems to read higher than an actual egt sensor in the mani does from whats posted up...you had said the pcm makes a calculation, so I just think it's pretty off
I think you'd be surprised at how hot the EGT's get on these cars. I have an actual EGT sensor and I believe it gets over 1650 deg even with my 50 trim. I'll have to check my notes.
Todd
I'm not surprised at getting close to 1700, I know it's not hard to do, but 1700+ is too hot to hold, and according to this gauge, 1700 comes on well before redline and holds that high....this gauge seems to read higher than an actual egt sensor in the mani does from whats posted up...you had said the pcm makes a calculation, so I just think it's pretty off
In my first post in this thread I noted that the PCM EGT values were consistently about 100 degrees higher than what my actual EGT sensor read. I don't understand your point. You say it's "pretty off", that was determined a long time ago. Do you think they are off by more than what I reported already? The point I was making is that we know the PCM value is 100 degrees higher than what you'd see with a sensor mounted in the exhaust manifold. Knowing this, I believe the readings are still useful. I have not received much data from others, I guess not that many people are using actual EGT sensors, but what little I've received seems to back up what I found last year.
I was agreeing with you, even quoting you....100+ degrees is "pretty off" to me, I don't know about anyone else..it's not a knock on the gauge at all since the readings come from the pcm....you had said it's surprising how hot it gets, that's no surprise, I can't count how many times it's been said to avoid sustained temps over 1700....just looking to make sense of the reading on the gauge cause mine seemed a bit higher than others, thanks for looking into it
I did some pulls today and watched the actual and PCM EGT readings. Keep in mind that I have a 50 trim turbo so I'm not heating the air as much a stocker for example.
At the top of 2nd and through 3rd I was seeing 1605 on my actual EGT, and 1610 on the PCM EGT. The PCM has a much quicker response that my actual EGT, so through 1st and early in second it seemed like the PCM reading was abotu 75-100 hight than the actual. Once the actual caught up though they were pretty close. I'm installing a smaller turbo this week and will do more testing.
During cruise and light throttle the PCM reading is usually 75 degrees higher than actual.
Is there anyone else running an actual EGT and the Interceptor? I'd like to see further data.
I've had an EGT gauge mounted about 2" from port 1 of the cylinder head for a week now. These actual readings compare pretty well to those calculated by the PCM. I have a 50 trim turbo which may or my not effect the PCM determined EGT temperature.
Autometer EGT reading Interceptor EGT reading from PCM
750 (idle) deg F 950 deg F
1050 1125
1200 1275
1300 1400
1400 1500
1550 1650 (WOT)
Once the actual got over 1000 deg F the difference between the two was a fairly constant 100 deg. I don't know exactly where the PCM is determining the temperature, perhaps at the cylinder exit of combustion chamber. I'll be interested to see if the stock turbo readings are closer.
1. How exactly does the SRT-4 PCM calculate EGT's? (what are the input parameters).
2. What does the SRT-4 PCM use the calculated EGT's for? (is it just a byproduct calculation or does it actually influence the PCM to change other variables like boost, ignition advance timing, injector pulse widths, fuel trims).
Obviously, noone in the right mind would tune a car based solely on calculated EGT's. But those of us with OBD-II scan gauges are aware of the calculated EGT readout and would like to know more about it. Unfortunately, the PCM is a black box to everyone outside of DCX, hence this question to the SRT engineers.
We do not calculate EGT as part of the ECM. The EGT's are measured on the dyno and car and we do not cross selected limits depending on the Components in the exhaust flow such as the exhaust valve and the turbine wheel. the leaner , the hotter the EGT's, higher the power until parts break.
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Last edited by Team SRT : 07-18-2007 at 05:14 PM.
To be honest, I was quite suprised at this. So who is right? The SRT Engineers or you? It's not a huge deal. I just would like to know more about how and where the calculated EGT's are derived. Thanks!
I have the the Zeitronix with the ZAVT-2 warning/trigger option and the EGT probe and the Aeroforce dual pro setup....have to admit that with the EGT probe hooked into the Zeitronix I have not been looking at the Aeroforce for this data
I have the ZAVT-2 trigger setup for 1725f, I always trigger the ZAVT-2 for a brief moment while doing a WOT pull. My car is now where near stock anymore so I do not know how relevant my data would be.
Questions, whats considered "sustained"...meaning how long is sustained supposed to be? EGT is danger on its own or is it danger along with running leaner then stock.
I have the the Zeitronix with the ZAVT-2 warning/trigger option and the EGT probe and the Aeroforce dual pro setup....have to admit that with the EGT probe hooked into the Zeitronix I have not been looking at the Aeroforce for this data
I have the ZAVT-2 trigger setup for 1725f, I always trigger the ZAVT-2 for a brief moment while doing a WOT pull. My car is now where near stock anymore so I do not know how relevant my data would be.
Questions, whats considered "sustained"...meaning how long is sustained supposed to be? EGT is danger on its own or is it danger along with running leaner then stock.
As I recall, DodgeTweaker mentioned something about sustained EGT's at around that mark in the S2 thready. It's unlikely that he was talking about calculated EGT's, but anything is possible since it was just a passing remark. Anyway, if the PCM itself doesn't calculate EGT's as the SRT Engineers stated in response to my question, it would be good to get an answer about how those calculated EGT's are derived for the Aeroforce gauge.
To be honest, I was quite suprised at this. So who is right? The SRT Engineers or you? It's not a huge deal. I just would like to know more about how and where the calculated EGT's are derived. Thanks!
Interesting. Why though is it a question of who's right/wrong? That's a rather odd statement. There is no documentation describing this parameter, up to now it's been conjecture based on real world testing. I posted my results as have others, you make your own conclusion as to the value of this parameter. Dodge must have had a reason to put it on the data stream, we simply provide access to it.
To be honest, I was quite suprised at this. So who is right? The SRT Engineers or you? It's not a huge deal. I just would like to know more about how and where the calculated EGT's are derived. Thanks!
Interesting. Why though is it a question of who's right/wrong? That's a rather odd statement. There is no documentation describing this parameter, up to now it's been conjecture based on real world testing. I posted my results as have others, you make your own conclusion as to the value of this parameter. Dodge must have had a reason to put it on the data stream, we simply provide access to it.
Todd
Sorry, I wasn't trying to corner anyone into a who's right/wrong question. I was just interested in how it really works. My guess is that the SRT Engineers probably answered the questions I asked about as well as their management would permit. So it's unlikely they will be inclined to tell us any more than that.
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