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Elec system effect oil temp?

Rob S.

Rob S.

Forum Guru
Past Site Supporter
I'll try one more time. Posplayr, others please help me to understand. The SH-775 (or any electric system upgrade) is not near the top of my to-do list, but I would like to understand.

When I met Frank, of Powerhouse Motorcycles last week (http://www.fastcycles.com/), I asked him if upgrading the R/R could lower the oil temp. "No," he said, "that's the electrical system."

Please correct any mistakes in the following:

The stator dumps heat into the engine oil.

The SH-775 (or other R/R upgrade) (will definitely) (might?) lessen the amount of heat that the stator transfers to the engine oil.

Am I getting warm?
 
Why is it hard to understand?

Shunting electricity through the stator makes heat. It is inside the engine. The engine will get hotter. How much? I don't know. Not much. Little bit.

The guys who have tested it know more.

Kind of like how those little coffee heaters that go inside the cup keep your coffee hot.
 
Not hard to understand, I just never got a straight answer.

Thanks for the info.
 
To the contrary of tkent, the heat in a wire, coil of wire, or in this case a stator is directly related to the current flowing through it. Because the SH-775 cuts off draw from the stator to regulate voltage vs shunting the excess, the average current flow in the stator is less which makes the heat from current flow less which makes for a cooler stator.

Rob, you are on the right track but considering the oil temp on an air cooled bike is over 200?F routinely and thus designed the oil temp difference from the upgraded R/R probably won't be worth the cost and effort by itself. The upgrade has other benefits like stator longevity but if your going into it for the reduced oil temp alone it probably won't feel worth it.
 
Wow man, how many threads do we need on the same subject? You must enjoy reading about me and Jim (Pos) disagreeing.:(

Some facts...

The stator provides power for the bike. Any extra power that is not consumed by the ignition, lights, etc, is returned to the stator (assuming a shunting R/R) where it's then converted into heat.

A GS1000 stator is rated at 18A, which converts to roughly 216 watts (18A x 12 volts).

There are two heat sources inside the engine: Combustion heat AND stator heat.

Heat moves from hot to cold.

In order for the stator to heat the oil above that which combustion heat alone would, the stator must be hotter than the oil, then it must come in contact with the oil, either directly or indirectly.

There is no direct oil flow on the stator. There is some splash lubrication though. The stator also conducts heat into the stator cover, which is then conducted into the entire mass of the engine.

Ideally the engine oil will stay at 220F and below.

So the questions is: does the stator get hotter than the combustion driven oil temp, and if so, how much heat is transferred to the oil?


On my GS1000 I've seen oil temps of 300F on a hot day, and my bike has a series R/R. In order for the stator to contribute to this temp, the stator itself must be HOTTER than 300F (which of course it isn't).

Draw your own conclusions, but I'm not ready to believe the stator contributes significantly to engine oil temp. Want to know for sure? Do a test. Take a good long ride and observe oil temp. Stop at the point where the temp stops rising and disconnect the stator. Then continue on your ride and observe if the oil temp drops. Bet you a beer there won't be much if any temp reduction.:cool:
 
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Killer2600 said:
To the contrary of tkent, the heat in a wire, coil of wire, or in this case a stator is directly related to the current flowing through it. Because the SH-775 cuts off draw from the stator to regulate voltage vs shunting the excess, the average current flow in the stator is less which makes the heat from current flow less which makes for a cooler stator.

Rob, you are on the right track but considering the oil temp on an air cooled bike is over 200?F routinely and thus designed the oil temp difference from the upgraded R/R probably won't be worth the cost and effort by itself. The upgrade has other benefits like stator longevity but if your going into it for the reduced oil temp alone it probably won't feel worth it.
Click to expand...

That's not at all contrary to what I said. I agree with all of it.
 
Steve said:
Only if they have a temp gauge. :p

.
Click to expand...

That is part of the point, everybody with a big block that has made the switch had a temp gauge to register the changes.

Those with stock 1100's also had temp gauges but the effects were much less.

I may be mistaken but I don't think anybody tried to verify with the tip of their tongue although a lot of lip service has been provided. :rolleyes:
 
posplayr said:
That is part of the point, everybody with a big block that has made the switch had a temp gauge to register the changes.

Those with stock 1100's also had temp gauges but the effects were much less.

I may be mistaken but I don't think anybody tried to verify with the tip of their tongue although a lot of lip service has been provided. :rolleyes:
Click to expand...

Why would a big block see a larger reduction in stator heating than a stock 1100?
 
I think he (Pos) is making the point that those with big blocks were more-likely to have a gauge. :-k

And since they had a gauge, they noticed the difference.

.
 
I don't think the smaller bikes ever had any problems with the oil running hot.
 
Nessism said:
Why would a big block see a larger reduction in stator heating than a stock 1100?
Click to expand...

Ed, have you ever heard of "the straw that breaks the camel's back"?

Big blocks depending upon size are closer to thermal limits that smaller bikes.

So what do you think happens when you add more heat?
 
Steve said:
I think he (Pos) is making the point that those with big blocks were more-likely to have a gauge. :-k

And since they had a gauge, they noticed the difference.

.
Click to expand...

Speaking as plain as possible. All GS1100E's have temp gauges and normally the owners spend some attention in watching them because the temp can climb to 270degF (indicated) or higher.


So when there is a sudden change (after a Series R/R switch) and the needle doesn't travel nearly as sky high as it did before, the only logical, rational and pragmatic conclusion is that there was a one to one cause and effect. Series R/R's lower the operating temperature.

There has been plenty of AA (amateur analysis) to prove that the temperature gauge needle can not drop because of the R/R, but that self delusional process defies the facts.
 
Some more AA for Jim's benefit...

Temperature: 83F

Ran 30 miles on my 1000S with a FH-009 shunt style R/R and checked temp. Then ran 30 miles back after switching to the SH-775. Checked gauge calibration by putting a thermocouple down into the oil. Judge for yourself.












 
The oil temp was in the 290F range when blasting on the freeway at 80 mph. There was a fair bit of traffic so the air temp may have been hotter than mentioned above. When slowing down the temp dropped quickly. The final temp (photos) were taken after getting off the freeway and then driving about 1/2 mile.

Bottom line: the R/R is the least of the bikes problems when it comes to heat. A large GS running at fast freeway speed runs HOT. I run synthetic oil but I'd run an oil cooler as well if this was my daily driver. Good news is the bike didn't care about the temp; bike ran flawlessly and didn't show any stress due to heat. Gotta love the toughness of the GS engines.


Claim: stator heat increase oil temperature...

busted2.jpg
 
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Ed, I believe your pictures although not your analysis. It appears that your bike tends to run cooler or cool down quicker that the 1100's. Why, air flow probably. And again this effect only becomes pronounced for 1166 cc. Although at very high temps on a stock 1075 there is also a change noticeable. An and 1100 generally doesn't get hot from running fast, it tends to get hot running slow. And 80mph is not really blasting unless you are in 4th or perhaps 3rd gear.

What I can't understand however is how and why you can be so adamant that this proves that 16V BB doesn't see temperature drops when there are multiple people that say they have such experience? No need to answer, the question rhetorical.
 
Jim,

The discussion focus is whether or not a stator that's receiving returned (shunted) current from the R/R contributes to oil temperature. The type of engine and/or the state of tune of the engine is immaterial. My experiment clearly shows that shunt style R/R's do NOT increase oil temperature. It doesn't matter if my engine was a 1300cc monster or stock, the results would be the same. Stator heat does not increase oil temp.

BTW, hope you forgive me for not taking a photo of the gauge at 80 mph. Would have loved to, but decided against it. The oil temp maxed out at the exact same level regardless of whether the shunt or series R/R was installed.
 
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