You told me all I needed to know.

Thank you.

 

The temperature readings I gave come out of the calibration that is in a stock 2014 - 2016 Twin cooled bike. So the 27 deg C agrees, but the engine temperature is hotter than the service bulletin states. Other than this, they are the same and I will rely on the calibration values before I do a service bulletin.

 

I have to agree with Steve on this one....the oil temperature has been my concern since I first looked at how they routed the oil cooling. It is my belief they should have had a two section oil cooler. One section for cooling cylinder heads and a second section for cooling oil that goes through filter then we would be cooling all oil every pass of the pump. Keep in mind that a valve seat in any engine has two jobs. One is to seal combustion chamber and the second is to absorb heat from the valve so it doesn't overheat and burn/melt. Keep in mind what the exhaust temp is (600-1200F)...the valve seat is absorbing that and transferring that heat into the oil that is now returning to the oil pan super heated from the exhaust stream which can be in the area of 1200 F. What you potentially end up with is "heat saturated" oil since we are only cooling a percentage of the oil every pass of the pump. You will see the oil temps creep up throughout the ride as the current design can only dissipate so much heat that is absorbed into the oil (ride less with a modified engine as they create even more heat). typically a cooler will only lower the temp from inlet to outlet by 30F its just the way it works if the flow is correct. if the temp change is too large in a cooler you risk thermal shock which results in a failed leaking cooler......................

 

Problem is, this 80 degree EITMS thing is so well documented and in the service manual and owners manual (and common knowledge and observed countless times to those of us who own these bikes).
I'm beginning to question...

EDIT: I didn't like how that came out so I toned it down. I'm not here to beat up on sponsors/industry guys - unless it's Howard. JK

 

Steve, your posts sound like your not sure yet about the M8 and its oil cooling system??

I threw my initial question out for all to comment on because of my interest in owning a HD and not being a long time HD owner (I do own a 2015 BMW K 1600 GT) makes me a novice regarding the mechanics of the M8. Waiting for a better drive train makes perfect sense to me so my interest in the M8 is why I'm here.

I assume Steve is a veteran who works in a testing capacity for some entity that is paid to analyze engines? Or is he on his own for the betterment of the cycle world who likes to publish his findings for all to learn from? Just asking.

The opinions here are w/o a doubt not all on the same page regarding agreements on how the oil cooling process works in this engine as well as whether there is in fact measurable improvements in that area of the M8. And engine temps has always been a subject of discussion with many a HD rider I've met. Some good some not so good words from them on this issue.

 

For some reason this line of discussion reminds me of the oil pans Baker makes for twin cam touring bikes.

I am also having trouble believing there is a huge oil system design flaw that will spell the death of all M8's that are not garage queens.

The literature from HD says less heat is transferred to the heads in an M8 due to smaller surface area in the combustion chamber.

 

Maybe you should READ that service bulletin.

There is no distinction between water cooled vs air cooled models.

EITMS activates at 80 degrees F ambient air temperature for ALL Rushmore models with fairings.

EITMS activates at 288 degrees F (142 degrees C) engine temperature for ALL Rushmore models w/o fairings.


That is not what you're saying. My experience with Rushmore models has been that the EITMS operation works just like the service bulletin states.

 

While I'm not a mechanical engineer with a background in thermodynamics, I've spent a bunch of time dealing with with thermal issues in big computers and power transistors for high power applications. I did manage to pick up a few things along the way..

While you are talking exhaust temps they are not temps at the valve seat / cylinder head.. The exhaust flow has a boundary layer just like in the combustion chamber that isolates the combustion temps and exhaust flow from the hard parts. The oil will not see these temps and anything above say 400F will affect the strength of the head itself.

I can see the oil being heated to say 300 to 350 for short periods of time but the good thing is that the oil don't need to lubricate at these temps, only cool.. As long as the oil doesn't oxidize, it's OK. Oil at temps are definitely a good reason for selecting a good synthetic oil and changing it at shorter intervals if you want to extend the service life of the emissions qualified motor.

I don't see any reason for a second section to cool oil entering the filter..(your 2 section cooler) For one the filter acts as an oil cooler itself. Second hot oil flows better through the filter reducing pressure drop to the motor.

While the big issue might be what the oil temps are, as long as the oil is cool enough to perform adequate lubrication and keep the lifters from bleeding down too fast (quiet), temps is not that important. The oil flowing through the exhaust passage is cooling the heads where most of the heat is being generated.

The only improvement I can see would be to place the oil cooler at the location where the oil temperature is highest which is the cylinder head exits.. That location is where the oil temps will be the highest and where the oil temperature is highest. This point is where the oil cooler can do it best..

Your idea of thermal shock is not correct.. It's really a temperature gradient that the coil cooler needs to be dealt with.. Temps do change and the oil cooler needs to be sound enough to handle with it.

In thermodynamics and other things where energy is being discussed, its best to draw a box around the device (motor) and look at the flow of energy in and out of the box..

https://en.wikipedia.org/wiki/Conservation_of_energy

 

while it does show return or source from oil pan it gives us part of the picture

 

Interesting, that video is not correct.. The oil returns to the oil tank..




Above is a picture of the oil line from an oil cooled motor. Notice the exit is on the oil pan side.. I suspect that the video is a oil cooled concept based on the coolant version of the system before the final version.. If you look up the coolant based cooling lines they feed back to the front.