M8 Twin Cooling engine temp info - don't close those vents!!
#1
04-10-2017, 07:40 PM
The following 3 users liked this post by Heatwave:
#3
04-10-2017, 09:31 PM
Big Kahuna HDF Member
#4
04-10-2017, 10:07 PM
Seasoned HDF Member
#5
04-10-2017, 10:52 PM
Outstanding HDF Member
That is a good idea. The amount of heat coming off the radiator could be used to keep you warm on cold mornings but not restrict flow to the radiators.
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tnglide (05-28-2019)
#6
04-11-2017, 09:15 AM
Stellar HDF Member
#7
04-12-2017, 07:37 PM
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#8
04-13-2017, 09:23 AM
I have a 2017 CVO Limited that has been upgraded with the Stage IV kit, Street Cannons, FM Jackpot headpipe and FM tuning with Powervision. I gained some insight this weekend about how this new Twin-Cooled M8 engine manages temps and I figured I would share with the forum.
The advantage of this build with the Powervision is the ability to view lots of data about the engine while I'm riding under normal conditions. I have the 6 gauge screen setup on my PV to view " Engine Temp", "Head Temp" and "Coolant Temp" and other metrics. I had the chance this past weekend to observe the relationship of these various temps on a day when the air temps started at 30 degrees and finished near 70 degrees.
Here's my learnings.
- normal Engine temps at full operation is about 250 degrees after some hard running with the lower vents fully open.
- at 250 degrees ET, the "Head Temps" will generally be about 15 degrees higher than the engine temps (~265)
- at 250 degrees ET, the coolant temp will vary based on ambient temp, airflow, how hard the engine is working but generally if you are moving "at speed" the coolant temp will be in the 160-170 range. If the bike is idling at a light, the coolant temp can rise quickly. If the coolant reaches 194 and the bike is moving less than 14 mph, the radiator fans will kick on and the coolant temp will quickly fall. Once the coolant temp falls to 181, the fans turn off. The fans will also come on when the bike is turned off, if the coolant temp is above 194. The fans will remain on for 180 secs after the engine is turned off. These fan on/off parameters are the factory settings in the HD maps.
Interesting learnings:
- if you close the lower vents, for example on a cold morning, as the air temps rise, if you forget to open the vents, the Engine temps will quickly rise to 300+ degrees. You'll know the ET has risen above 284 degrees because you will feel the bike losing power as the tuning map begins to lower spark advance to protect the engine and avoid knocking.
- I inadvertently left one side vent one notch from being fully open. The other lower vent was fully open. Even that slight reduction in lower vent air flow was enough to raise the engine temp over 25 degrees into the 275-285 range. Within a few mins after I figured out why the temps were higher and opened the vent 100%, the ET came back down to the 245-250 range.
-if the engine temps get up to 300+ (vents closed for example), the Head Temps will generally be about 20+ degrees higher. Coolant temps will rise into the 210-230 range.
My conclusion:
-I will ALWAYS keep the lower vents fully opened 100%, all the time. Its too easy to forget they are closed or partially closed and if you ride for a long time with the vents closed the engine can get "heat loaded" and it can become difficult to get the temps lowered without turning off the engine. Better to keep the engine from ever getting "heat loaded" by keeping the lower vents open all the time.
Curious if any others have found similar engine heating impact from the vent positions on their M8 with Twin-Cooling.
The advantage of this build with the Powervision is the ability to view lots of data about the engine while I'm riding under normal conditions. I have the 6 gauge screen setup on my PV to view " Engine Temp", "Head Temp" and "Coolant Temp" and other metrics. I had the chance this past weekend to observe the relationship of these various temps on a day when the air temps started at 30 degrees and finished near 70 degrees.
Here's my learnings.
- normal Engine temps at full operation is about 250 degrees after some hard running with the lower vents fully open.
- at 250 degrees ET, the "Head Temps" will generally be about 15 degrees higher than the engine temps (~265)
- at 250 degrees ET, the coolant temp will vary based on ambient temp, airflow, how hard the engine is working but generally if you are moving "at speed" the coolant temp will be in the 160-170 range. If the bike is idling at a light, the coolant temp can rise quickly. If the coolant reaches 194 and the bike is moving less than 14 mph, the radiator fans will kick on and the coolant temp will quickly fall. Once the coolant temp falls to 181, the fans turn off. The fans will also come on when the bike is turned off, if the coolant temp is above 194. The fans will remain on for 180 secs after the engine is turned off. These fan on/off parameters are the factory settings in the HD maps.
Interesting learnings:
- if you close the lower vents, for example on a cold morning, as the air temps rise, if you forget to open the vents, the Engine temps will quickly rise to 300+ degrees. You'll know the ET has risen above 284 degrees because you will feel the bike losing power as the tuning map begins to lower spark advance to protect the engine and avoid knocking.
- I inadvertently left one side vent one notch from being fully open. The other lower vent was fully open. Even that slight reduction in lower vent air flow was enough to raise the engine temp over 25 degrees into the 275-285 range. Within a few mins after I figured out why the temps were higher and opened the vent 100%, the ET came back down to the 245-250 range.
-if the engine temps get up to 300+ (vents closed for example), the Head Temps will generally be about 20+ degrees higher. Coolant temps will rise into the 210-230 range.
My conclusion:
-I will ALWAYS keep the lower vents fully opened 100%, all the time. Its too easy to forget they are closed or partially closed and if you ride for a long time with the vents closed the engine can get "heat loaded" and it can become difficult to get the temps lowered without turning off the engine. Better to keep the engine from ever getting "heat loaded" by keeping the lower vents open all the time.
Curious if any others have found similar engine heating impact from the vent positions on their M8 with Twin-Cooling.
#9
04-13-2017, 01:13 PM
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I have a 2017 CVO Limited that has been upgraded with the Stage IV kit, Street Cannons, FM Jackpot headpipe and FM tuning with Powervision. I gained some insight this weekend about how this new Twin-Cooled M8 engine manages temps and I figured I would share with the forum.
The advantage of this build with the Powervision is the ability to view lots of data about the engine while I'm riding under normal conditions. I have the 6 gauge screen setup on my PV to view " Engine Temp", "Head Temp" and "Coolant Temp" and other metrics. I had the chance this past weekend to observe the relationship of these various temps on a day when the air temps started at 30 degrees and finished near 70 degrees.
Here's my learnings.
- normal Engine temps at full operation is about 250 degrees after some hard running with the lower vents fully open.
- at 250 degrees ET, the "Head Temps" will generally be about 15 degrees higher than the engine temps (~265)
- at 250 degrees ET, the coolant temp will vary based on ambient temp, airflow, how hard the engine is working but generally if you are moving "at speed" the coolant temp will be in the 160-170 range. If the bike is idling at a light, the coolant temp can rise quickly. If the coolant reaches 194 and the bike is moving less than 14 mph, the radiator fans will kick on and the coolant temp will quickly fall. Once the coolant temp falls to 181, the fans turn off. The fans will also come on when the bike is turned off, if the coolant temp is above 194. The fans will remain on for 180 secs after the engine is turned off. These fan on/off parameters are the factory settings in the HD maps.
Interesting learnings:
- if you close the lower vents, for example on a cold morning, as the air temps rise, if you forget to open the vents, the Engine temps will quickly rise to 300+ degrees. You'll know the ET has risen above 284 degrees because you will feel the bike losing power as the tuning map begins to lower spark advance to protect the engine and avoid knocking.
- I inadvertently left one side vent one notch from being fully open. The other lower vent was fully open. Even that slight reduction in lower vent air flow was enough to raise the engine temp over 25 degrees into the 275-285 range. Within a few mins after I figured out why the temps were higher and opened the vent 100%, the ET came back down to the 245-250 range.
-if the engine temps get up to 300+ (vents closed for example), the Head Temps will generally be about 20+ degrees higher. Coolant temps will rise into the 210-230 range.
My conclusion:
-I will ALWAYS keep the lower vents fully opened 100%, all the time. Its too easy to forget they are closed or partially closed and if you ride for a long time with the vents closed the engine can get "heat loaded" and it can become difficult to get the temps lowered without turning off the engine. Better to keep the engine from ever getting "heat loaded" by keeping the lower vents open all the time.
Curious if any others have found similar engine heating impact from the vent positions on their M8 with Twin-Cooling.
The advantage of this build with the Powervision is the ability to view lots of data about the engine while I'm riding under normal conditions. I have the 6 gauge screen setup on my PV to view " Engine Temp", "Head Temp" and "Coolant Temp" and other metrics. I had the chance this past weekend to observe the relationship of these various temps on a day when the air temps started at 30 degrees and finished near 70 degrees.
Here's my learnings.
- normal Engine temps at full operation is about 250 degrees after some hard running with the lower vents fully open.
- at 250 degrees ET, the "Head Temps" will generally be about 15 degrees higher than the engine temps (~265)
- at 250 degrees ET, the coolant temp will vary based on ambient temp, airflow, how hard the engine is working but generally if you are moving "at speed" the coolant temp will be in the 160-170 range. If the bike is idling at a light, the coolant temp can rise quickly. If the coolant reaches 194 and the bike is moving less than 14 mph, the radiator fans will kick on and the coolant temp will quickly fall. Once the coolant temp falls to 181, the fans turn off. The fans will also come on when the bike is turned off, if the coolant temp is above 194. The fans will remain on for 180 secs after the engine is turned off. These fan on/off parameters are the factory settings in the HD maps.
Interesting learnings:
- if you close the lower vents, for example on a cold morning, as the air temps rise, if you forget to open the vents, the Engine temps will quickly rise to 300+ degrees. You'll know the ET has risen above 284 degrees because you will feel the bike losing power as the tuning map begins to lower spark advance to protect the engine and avoid knocking.
- I inadvertently left one side vent one notch from being fully open. The other lower vent was fully open. Even that slight reduction in lower vent air flow was enough to raise the engine temp over 25 degrees into the 275-285 range. Within a few mins after I figured out why the temps were higher and opened the vent 100%, the ET came back down to the 245-250 range.
-if the engine temps get up to 300+ (vents closed for example), the Head Temps will generally be about 20+ degrees higher. Coolant temps will rise into the 210-230 range.
My conclusion:
-I will ALWAYS keep the lower vents fully opened 100%, all the time. Its too easy to forget they are closed or partially closed and if you ride for a long time with the vents closed the engine can get "heat loaded" and it can become difficult to get the temps lowered without turning off the engine. Better to keep the engine from ever getting "heat loaded" by keeping the lower vents open all the time.
Curious if any others have found similar engine heating impact from the vent positions on their M8 with Twin-Cooling.
We've just barely begun doing our heat testing on the M8's, but have seen that while the M8 has a lot going for it, HD still did not solve the heat issue. We're seeing a lot of the same things on the M8 that we've seen on the Twin Cam. HERE is a report we did a while back.
Heat & Performance on the Dyno-
The M8 reacted very similar to the Twin Cam on the dyno in regards to heat.
When doing comparative Dyno pulls it is important to have the engine temperature the same with every pull.
On both the Twin Cams and the M8, when the cylinder head temp crosses the 250* line power drops off, significantly.
We always get the engines heat soaked, then use the dyno fans to try and keep the temperature stable. However, just like on the Twin Cams, the M8 will go past the 250* mark very easily, even with the fans on. So there are times when we have to wait for the engine to cool down to get to our 240-245 range for accurate comparative pulls.
The upshot of all this is that the M8, while have less felt heat, still seems to have the same overheating challenges that the Twin Cam does.
When doing comparative Dyno pulls it is important to have the engine temperature the same with every pull.
On both the Twin Cams and the M8, when the cylinder head temp crosses the 250* line power drops off, significantly.
We always get the engines heat soaked, then use the dyno fans to try and keep the temperature stable. However, just like on the Twin Cams, the M8 will go past the 250* mark very easily, even with the fans on. So there are times when we have to wait for the engine to cool down to get to our 240-245 range for accurate comparative pulls.
The upshot of all this is that the M8, while have less felt heat, still seems to have the same overheating challenges that the Twin Cam does.
Heat on the Road-
We had the M8 for two days, and both days were cool, in the 50's. So all of our testing of temperatures were in relatively cool ambient temps.
We were disappointed to see that the M8, again, while have less felt heat, has some serious temperature challenges.
At 70 MPH cruising, in 54* ambient temps, we saw the Front Cylinder at 290* and the Rear Cylinder at 310*. This was after only 30 minutes in cool temp riding, One-up.
Another 45 minute test, again, one-up and easy riding at 56* ambient temps, showed a front cylinder temp of 288* and a rear cylinder temp of 317*.
Since we already know, from our time on the Dyno, that the ECM is pulling spark (retarding the timing) when it crosses the 250* mark, we know that in everyday riding, even when it is cool out, that the engine is not performing optimally, power-wise AND MPG-wise.
We were disappointed to see that the M8, again, while have less felt heat, has some serious temperature challenges.
At 70 MPH cruising, in 54* ambient temps, we saw the Front Cylinder at 290* and the Rear Cylinder at 310*. This was after only 30 minutes in cool temp riding, One-up.
Another 45 minute test, again, one-up and easy riding at 56* ambient temps, showed a front cylinder temp of 288* and a rear cylinder temp of 317*.
Since we already know, from our time on the Dyno, that the ECM is pulling spark (retarding the timing) when it crosses the 250* mark, we know that in everyday riding, even when it is cool out, that the engine is not performing optimally, power-wise AND MPG-wise.
#10
04-13-2017, 01:20 PM
Seasoned HDF Member
Great info! Thanks for posting it.
We've just barely begun doing our heat testing on the M8's, but have seen that while the M8 has a lot going for it, HD still did not solve the heat issue. We're seeing a lot of the same things on the M8 that we've seen on the Twin Cam. HERE is a report we did a while back.
Below is a copy and paste of a post on and oil cooled M8-
Heat & Performance on the Dyno-
Heat on the Road-
We've just barely begun doing our heat testing on the M8's, but have seen that while the M8 has a lot going for it, HD still did not solve the heat issue. We're seeing a lot of the same things on the M8 that we've seen on the Twin Cam. HERE is a report we did a while back.
Below is a copy and paste of a post on and oil cooled M8-
Heat & Performance on the Dyno-
The M8 reacted very similar to the Twin Cam on the dyno in regards to heat.
When doing comparative Dyno pulls it is important to have the engine temperature the same with every pull.
On both the Twin Cams and the M8, when the cylinder head temp crosses the 250* line power drops off, significantly.
We always get the engines heat soaked, then use the dyno fans to try and keep the temperature stable. However, just like on the Twin Cams, the M8 will go past the 250* mark very easily, even with the fans on. So there are times when we have to wait for the engine to cool down to get to our 240-245 range for accurate comparative pulls.
The upshot of all this is that the M8, while have less felt heat, still seems to have the same overheating challenges that the Twin Cam does.
When doing comparative Dyno pulls it is important to have the engine temperature the same with every pull.
On both the Twin Cams and the M8, when the cylinder head temp crosses the 250* line power drops off, significantly.
We always get the engines heat soaked, then use the dyno fans to try and keep the temperature stable. However, just like on the Twin Cams, the M8 will go past the 250* mark very easily, even with the fans on. So there are times when we have to wait for the engine to cool down to get to our 240-245 range for accurate comparative pulls.
The upshot of all this is that the M8, while have less felt heat, still seems to have the same overheating challenges that the Twin Cam does.
Heat on the Road-
We had the M8 for two days, and both days were cool, in the 50's. So all of our testing of temperatures were in relatively cool ambient temps.
We were disappointed to see that the M8, again, while have less felt heat, has some serious temperature challenges.
At 70 MPH cruising, in 54* ambient temps, we saw the Front Cylinder at 290* and the Rear Cylinder at 310*. This was after only 30 minutes in cool temp riding, One-up.
Another 45 minute test, again, one-up and easy riding at 56* ambient temps, showed a front cylinder temp of 288* and a rear cylinder temp of 317*.
Since we already know, from our time on the Dyno, that the ECM is pulling spark (retarding the timing) when it crosses the 250* mark, we know that in everyday riding, even when it is cool out, that the engine is not performing optimally, power-wise AND MPG-wise.
We were disappointed to see that the M8, again, while have less felt heat, has some serious temperature challenges.
At 70 MPH cruising, in 54* ambient temps, we saw the Front Cylinder at 290* and the Rear Cylinder at 310*. This was after only 30 minutes in cool temp riding, One-up.
Another 45 minute test, again, one-up and easy riding at 56* ambient temps, showed a front cylinder temp of 288* and a rear cylinder temp of 317*.
Since we already know, from our time on the Dyno, that the ECM is pulling spark (retarding the timing) when it crosses the 250* mark, we know that in everyday riding, even when it is cool out, that the engine is not performing optimally, power-wise AND MPG-wise.