Question about Engine Temps
Seasoned HDF Member
Joined: Feb 2008
Posts: 23,001
Likes: 11,441
Here it goes again. For now forget Oil temps. The heat comes from the heads and exhaust,and CATs. Only one HD has oil cooled heads and it is not the one you have.
The oil flow to the heads is not enough to provide any cooling even if you lower the oil to 10 degrees.
One a modern Hd tvwin head temps have been recorded well above 300.
The way to lower them and the over all heat it a puzzle with a few peaces.
Air flow over the heads- Lenale fan, or other effective model. With the lenale unlike others the air flows through.
Get rid of the Cats. the right way, jack pot 2-1-2 or one like it
Free up the exhaust flow a bit. pipes with some restriction but not to much.
A proper tune for your mods
Last bring down over all oil temps- simple cheap check out-http://bigskyfan.tripod.com/id10.html
Get this worked out and you can lower over all Engine temps and heat felt on riders a lot. This is a Power vision shot 90 degree day traffic. 103 engine. Yes there is a head temp sensor and you can read it.
Lenale fan on for a minute ,big sky oil cooler fan on. It can be done.
But no one approach will do it.
The oil flow to the heads is not enough to provide any cooling even if you lower the oil to 10 degrees.
One a modern Hd tvwin head temps have been recorded well above 300.
The way to lower them and the over all heat it a puzzle with a few peaces.
Air flow over the heads- Lenale fan, or other effective model. With the lenale unlike others the air flows through.
Get rid of the Cats. the right way, jack pot 2-1-2 or one like it
Free up the exhaust flow a bit. pipes with some restriction but not to much.
A proper tune for your mods
Last bring down over all oil temps- simple cheap check out-http://bigskyfan.tripod.com/id10.html
Get this worked out and you can lower over all Engine temps and heat felt on riders a lot. This is a Power vision shot 90 degree day traffic. 103 engine. Yes there is a head temp sensor and you can read it.
Lenale fan on for a minute ,big sky oil cooler fan on. It can be done.
But no one approach will do it.
Last edited by smitty901; Jun 23, 2013 at 10:20 AM.
Ultimate HDF Member
Joined: Nov 2005
Posts: 5,926
Likes: 138
From: NE Ohio
TTS doesn't log head temp, it gives what they call an engine temp. I haven't done IR head temps in quite awhile, last time was when the 2010 Triglide I had was stock. I was seeing 375 - 400 at the base of the spark plug on the rear head while running at 55 mph on a 75 degree day, the front was around 25 degrees cooler.
Last edited by msocko3; Jun 23, 2013 at 03:17 PM.
Cruiser
Joined: Jun 2012
Posts: 141
Likes: 8
From: Tasmania
The engine temp comes from a sensor in the rear left side of the front head.
TTS monitors the temp and it can be logged if it is added to the log info.
TTS monitors the temp and it can be logged if it is added to the log info.
Club Member
Joined: Aug 2007
Posts: 10,393
Likes: 2,060
From: N. Atlanta Burbs
There is no such real animal as "engine temp" logged by anything. There is no such sensor.
The engine temp number you see is made up of an algorithm via computations which include the "head temp" sensor. How this is computed depends on which tuner you use. The Delphi ECM doesn't have an engine temp computation of its own.
Bottom line... the "engine temp" you see is a lie based on other variables which can be seen by the Delphi ECM.
Kevin, the reason why you are not getting this question answered where you have posted it in the past may be due to not many people log it. I have dozens upon dozens of logs with head and so called engine temp readings. They vary from bike to bike, ambient temp, riding style and even the way a rider sits on the bike. Example... I have logs for stock TG's that will vary from 230* engine temp to 320* (remembering this temperature is a lie).
Head temps will vary causing the made up engine temp to vary as well. After riding for about 30 minutes at a constant speed you will find the head temp and engine temp readings to be very close to each other. Due to the physics of a Harley motor the front cylinder will always run cooler. There is no head temp sensor on the rear cylinder which receives less circulatory air. Therefore there is no real way for "engine temp" to be accurate unless there were multiple temperature sensors placed through out the motor.
Actually.....
There is no such real animal as "engine temp" logged by anything. There is no such sensor.
The engine temp number you see is made up of an algorithm via computations which include the "head temp" sensor. How this is computed depends on which tuner you use. The Delphi ECM doesn't have an engine temp computation of its own.
Bottom line... the "engine temp" you see is a lie based on other variables which can be seen by the Delphi ECM.
Kevin, the reason why you are not getting this question answered where you have posted it in the past may be due to not many people log it. I have dozens upon dozens of logs with head and so called engine temp readings. They vary from bike to bike, ambient temp, riding style and even the way a rider sits on the bike. Example... I have logs for stock TG's that will vary from 230* engine temp to 320* (remembering this temperature is a lie).
Head temps will vary causing the made up engine temp to vary as well. After riding for about 30 minutes at a constant speed you will find the head temp and engine temp readings to be very close to each other. Due to the physics of a Harley motor the front cylinder will always run cooler. There is no head temp sensor on the rear cylinder which receives less circulatory air. Therefore there is no real way for "engine temp" to be accurate unless there were multiple temperature sensors placed through out the motor.
There is no such real animal as "engine temp" logged by anything. There is no such sensor.
The engine temp number you see is made up of an algorithm via computations which include the "head temp" sensor. How this is computed depends on which tuner you use. The Delphi ECM doesn't have an engine temp computation of its own.
Bottom line... the "engine temp" you see is a lie based on other variables which can be seen by the Delphi ECM.
Kevin, the reason why you are not getting this question answered where you have posted it in the past may be due to not many people log it. I have dozens upon dozens of logs with head and so called engine temp readings. They vary from bike to bike, ambient temp, riding style and even the way a rider sits on the bike. Example... I have logs for stock TG's that will vary from 230* engine temp to 320* (remembering this temperature is a lie).
Head temps will vary causing the made up engine temp to vary as well. After riding for about 30 minutes at a constant speed you will find the head temp and engine temp readings to be very close to each other. Due to the physics of a Harley motor the front cylinder will always run cooler. There is no head temp sensor on the rear cylinder which receives less circulatory air. Therefore there is no real way for "engine temp" to be accurate unless there were multiple temperature sensors placed through out the motor.
I called dynojet today, and spoke with two different techs there. Both said the "engine temp" readout on the Power Vision gauge is a direct feed of the front cylinder head temp, no algorithms.
Dunno if that is true or not, but that is what they said.
It would definitely be nice to have a sensor in the rear cylinder head, but whenever I have shot them with the IR gun the rear cylinder is usually 20-30* hotter than the front.
Advanced
Joined: May 2007
Posts: 57
Likes: 0
From: Canada
Rear Cylinder Temps
Wiz, what percentage increase are you running your Rear VE tables over the front VE tables to drop rear cylinder temp?
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Club Member
Joined: Aug 2007
Posts: 10,393
Likes: 2,060
From: N. Atlanta Burbs
There is no rule that says the back cylinder has to run higher % VE cells due to heat. They may be very near the % of the front cylinder or the front cylinder could be much higher. What you are measuring is fuel mixture.
This or any VE difference between front and rear cylinders is more mechanical than heat related. Intake manifold or valve leakage, out of round cylinder bores or bypassing piston rings. Even an exhaust leak at the head can change the VE cells not to mention a poor injector or electrical connection.
Measuring free oxygen is the only way to find the real Volumetric Efficiency of a burn event and this is only read as history of the combustion. Therefor, all of the above mechanical events are suspect when large % differences are found between the front and rear cylinder.
It's not a given that the rear cylinder will have a greater percentage of VE over the front.
Hope this makes sense.
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