Head Temps
There are several temp related channels within the Delphi ECM. The most common channel used is Engine Temperature which is based directly off the 0-5V signal from the ET sensor on the front cylinder head, this channel is reported on the databus as ET. Generally speaking when we speak of engine temp we refer to the data from this channel, we usually consider 240-320F about the normal range relative to conditions, engine mods, and other variables. The second channel is Head Temperature which this is a bit more complex, it is a model the ECM calculates based on the ET sensor, the intake air temp (IAT) and other factors. Head Temp is used within the ECM primarily for Spark Temp correction, for most combination it will run between 260-400F. Note: Heat Temp has been recently added to the PV channel list an is reported as HeadT. The last channel is Coolant Temp which is active on twin cooled and V Rod applications. Hope this info helps...
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Jamie Long / Fuel Moto USA
The USA's Leader V-Twin EFI & Performance www.fuelmotousa.com
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Jamie Long / Fuel Moto USA
The USA's Leader V-Twin EFI & Performance www.fuelmotousa.com
Contact 920-423-3309
Email jamie@fuelmotousa.com
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
Likes: 19
From: Naples FL / Pine TWP PA
All of the temps posted here may or may not be out of alignment with "normal" it just depends on the conditions, there is no simple XXXF temp that can be considered normal across the spectrum of operation but 320+ on the front head is not uncommon, lots of variables that influence temps. At long distance sustained highway speeds of 70+ MPH the CHTs can get just as hot as idling in town.
At about 55 MPH the CHTs will remain much lower because that is about the ideal combination of speed and RPM where the engine is shedding as much heat as its making, above or below it will climb higher.
ET and CHT is the same thing, front cylinder head OEM ET sensor. I'm not sure what the PV is reading as ET and CHT because there is only one sensor in the front head
I wouldn't try to draw any conclusions from IR temp gun reading at the spark plug, especially after shutdown, you can se why by looing at the first graph on the performance charts page I recently published on the website http://www.wardspartswerks.com/new-p...ance-data.html Actually studying the trends demonstrated in the data logged charts can help to explain a lot of what happens with CHTs during operation.
Conventional wisdom regarding Harley temps is mostly inaccurate, I've been studying this subject for several years now and I'm still learning new stuff all the time.
At about 55 MPH the CHTs will remain much lower because that is about the ideal combination of speed and RPM where the engine is shedding as much heat as its making, above or below it will climb higher.
ET and CHT is the same thing, front cylinder head OEM ET sensor. I'm not sure what the PV is reading as ET and CHT because there is only one sensor in the front head
I wouldn't try to draw any conclusions from IR temp gun reading at the spark plug, especially after shutdown, you can se why by looing at the first graph on the performance charts page I recently published on the website http://www.wardspartswerks.com/new-p...ance-data.html Actually studying the trends demonstrated in the data logged charts can help to explain a lot of what happens with CHTs during operation.
Conventional wisdom regarding Harley temps is mostly inaccurate, I've been studying this subject for several years now and I'm still learning new stuff all the time.
Thread Starter
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Road Warrior
Joined: Jul 2013
Posts: 1,624
Likes: 13
From: Fort Worth
I worked on this very issue with my bike and CHT running up over 300. I got it down to 260 on a hot day in closed loop mode @ 75 MPH running speed. The valve train is a lot quieter with the cylinder head temp down. As matter of fact the entire motor is a lot quieter. I already sucked a guide from high cylinder head temps, I wasn't about to do it again.
Cruiser
Joined: Sep 2013
Posts: 185
Likes: 0
From: Earth
I don't think updating my PV is going to do it for me. I have had my engine apart down to the cases and on an '09 the ET sensor is the only one, which is in the front head. Maybe in the '13's they have added a sensor, if so it would be interesting to know where the additional sensor is located. My ET's are in the 270 degree range when cruising at 70+ mph, I have an older set of FCS so they don't do much once the speeds get above 50. They work great in traffic though!
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
Likes: 19
From: Naples FL / Pine TWP PA
Yeah it seems to be the case. I was not aware there are two different measurements for CHT. I'll still send you the map if you want it. I got busy with the family yesterday and didn't get to getting it off my netbook. However it looks like you are good to go at this point.
Banned
Joined: Apr 2012
Posts: 648
Likes: 9
From: WV
There are several temp related channels within the Delphi ECM. The most common channel used is Engine Temperature which is based directly off the 0-5V signal from the ET sensor on the front cylinder head, this channel is reported on the databus as ET. Generally speaking when we speak of engine temp we refer to the data from this channel, we usually consider 240-320F about the normal range relative to conditions, engine mods, and other variables. The second channel is Head Temperature which this is a bit more complex, it is a model the ECM calculates based on the ET sensor, the intake air temp (IAT) and other factors. Head Temp is used within the ECM primarily for Spark Temp correction, for most combination it will run between 260-400F. Note: Heat Temp has been recently added to the PV channel list an is reported as HeadT. The last channel is Coolant Temp which is active on twin cooled and V Rod applications. Hope this info helps...
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Road Warrior
Joined: Jul 2013
Posts: 1,624
Likes: 13
From: Fort Worth
I loaded my AT results yesterday and made several more test log runs. It's running great and the first run, I had about 15 knock events on the front and 20 on the rear after my initial timing changes. Mostly around 60 map and 2500 rpm range. I timed those out yesterday and managed to only get 1 event and have made the adjustment, just a little lower. I'm pretty aggressive on my timing and only retarded 2 degrees in those areas. I had to go 2.5 degrees for the one that came back.
If weather holds up tonight, I have several more logging runs to make where I can do all out WOT and a couple lugging up the hill to make sure I am spot on. It's nice to know that I can ditch the HeadT gauge and add something else in its place.
Yes, please do send the map when you have time. I'd love to study it as I am learning.
Excellent info, now I just need to understand it. The OEM ET sensor is mounted in the front head, so its taking a direct reading of the front CHT. Is the HeadT a digital logic method of modifying the actual ET sensor reading to representing rear CHT, what does the ECM use it for? I need a comprehensive understanding of how and why two different temp readings are being generated from one sensor to express "ET" and "HeadT", which are both another way of expressing CHT. Which PV manual will I find detailed info on HeadT?