Oil Temps Again

[Kyler]

There's a lot to be said for synthetic oils and this rig is proof of every one of them - I take it you're using synth? I just assumed that.

Suzuki Racing 100% synthetic 4T 10w40 with 80 ml of Liquid Moly. Copy of last oil analysis is in 1st post.

I just got 2 cases of Liqui Moly Racing Synth 4T 5w40 and will be switching to that after next weekend.

 

[Guest]

Sorry I am so late back to this, was off for a long weekend and then on the road for work...

Then I decided to check the temperatures around the motor using my pyrometer. The temp gauge was reading 295 degrees.

Coming out of the motor (temp taken on the fitting) the oil was 195.

On the fins of the cooler on the input side, temp was 170.

On the fins of the cooler on the exit side, temp was 125 (45 deg drop)

Returning into the motor (temp taken on the fitting) the oil was 160 (35 deg drop).

Weird. Does anyone know how much temperature drop I should expect?

No idea, it depends on the cooler, the ducting, the oil temp and the air temp. It is weird that the inlet side of the fins are hotter than the outlet side.

[/QUOTE]

That looks like a perfect first attempt at the test ducting. I look forward to hearing your numbers from the next race. If you saw a 30 degree drop with just the box fan you should see significantly more drop in oil temp under racing conditions. You will have much better airflow into the cooler and the oil temp will be higher, which increases the cooler efficiency (efficiency is directly proportional to the temp difference between the hot fluid and the cooling medium, so your cooler will be more efficient on cooler days as well).

I'm just wondering how much cooling burden is being shifted to the oil if the direct engine cooling is compromised.

That is a fair question, which is why I asked about the engine cooling as well. There is only so much heat that can be pulled out of the engine by the oil.

The NACA ducts (although not period but tolerated) point at the jugs. That is the best I can do on that right now. I'll puzzle through cooling more after the next race and have more data. More to come!

Do they just point in the general direction of the engine? Ducting and jacketing will work here as well if you feel like making the effort.

What you've got to realise is that the argument is academic as THE OUTFIT MUST MATCH CORRECT PERIOD APPEARANCE.

That is fine, but didn't they use vents and air inlets of some sort for cooling in whatever period OP is racing in?

But I did order a TT Tech cylinder head temperature gauge. Knowing what is going on right now is job #1.

Too bad you didn't have that data from the unducted cooler setup to compare with the ducted version.


Mark

 

[posplayr]

Sorry I am so late back to this, was off for a long weekend and then on the road for work...



No idea, it depends on the cooler, the ducting, the oil temp and the air temp. It is weird that the inlet side of the fins are hotter than the outlet side.

That looks like a perfect first attempt at the test ducting. I look forward to hearing your numbers from the next race. If you saw a 30 degree drop with just the box fan you should see significantly more drop in oil temp under racing conditions. You will have much better airflow into the cooler and the oil temp will be higher, which increases the cooler efficiency (efficiency is directly proportional to the temp difference between the hot fluid and the cooling medium, so your cooler will be more efficient on cooler days as well).




That is a fair question, which is why I asked about the engine cooling as well. There is only so much heat that can be pulled out of the engine by the oil.




Do they just point in the general direction of the engine? Ducting and jacketing will work here as well if you feel like making the effort.




That is fine, but didn't they use vents and air inlets of some sort for cooling in whatever period OP is racing in?




Too bad you didn't have that data from the unducted cooler setup to compare with the ducted version.


Mark[/QUOTE]

From that data, it should be clear that you cannot measure oil temperature using a pyrometer :-\\\

How is it that the oil temperature climbs from 125 to 160 going from the cooler back to the motor? How can it possibly see that temperature rise? The simple answer is that the oil temperature can not be increasing with no heat input, so you have to conclude that the surface is not indicative of the oil temperature. You have to put a temp sensor into the oil.

 

[Kyler]

It is weird that the inlet side of the fins are hotter than the outlet side.

English is such an imprecise language I should have typed oil inlet to the cooler. I measured on the fin nearest to where the oil enters the cooler. Both measurements from the backside of the cooler.

Do they just point in the general direction of the engine? Ducting and jacketing will work here as well if you feel like making the effort.

Right now just the general direction. If I need more cooling I'll figure out how to add hoses and blow the air directly on the fins.

That is fine, but didn't they use vents and air inlets of some sort for cooling in whatever period OP is racing in?

Yes but not NACA ducts. Fortunately the rules aren't that tight in my class and no one is complaining. We have too few rigs to take a bike off the grid for nominal period incorrectness

From that data, it should be clear that you cannot measure oil temperature using a pyrometer :-\\\

the point was not to directly measure the oil temp rather get an idea of the heat. It is difficult to get accurate measurements from the oil fittings and the fins since they are of varying thicknesses. The fins probably gave a better indication of temp. After posting this I added a heat shield to mask exhaust header heat from the fittings leaving the motor. Unfortunately that also prevents me from getting a heat reading there in the future.

How is it that the oil temperature climbs from 125 to 160 going from the cooler back to the motor? How can it possibly see that temperature rise? The simple answer is that the oil temperature can not be increasing with no heat input, so you have to conclude that the surface is not indicative of the oil temperature. You have to put a temp sensor into the oil.

I agree and hence the heat shield mentioned above. The heat from the headers had to be increasing the temperature of the fittings.

And I guess you haven't read the whole thread? The first sentence in post #1 questions the accuracy of my temperature gauge. I have a new thermocouple coming from the same company that made my gauge. I was trying to get by with the thermocouple installed (the old gauge did not give a digital reading, only some vague LED light bars which I hated).

 

[posplayr]

And I guess you haven't read the whole thread? The first sentence in post #1 questions the accuracy of my temperature gauge. I have a new thermocouple coming from the same company that made my gauge. I was trying to get by with the thermocouple installed (the old gauge did not give a digital reading, only some vague LED light bars which I hated).

When you make a statement like question the accuracy of a gauge, my assumption is you are questioning the accuracy of a gauge. You now seem to be implying that when you say accuracy of a gauge, you really mean something else. I can only hazard a guess as this is a quite unconventional notion.

If the temperature at that local is not indicative of what you think you want to measure, that is not an accuracy issue. It is a sensor placement issue.

The accuracy of the gauge and sensor has nothing to do with where you mount it. While depending on where you mount it, it might not be measuring what you want, but that is a separate issue.

Just like the pyrometer, it could be perfectly accurate , but what you are doing with it to "measure " something is a different matter. The fact that the measurement is not "indicative" of what you want is not an accuracy issue.

It is clear that the pyrometer does not give a good indication of temperature of oil in the flow.

Assuming good accuracy, the oil temperature gauge should give an accurate reading at a particular point in the flow, if the sensor is exposed to the flow.

The reason I suggested measuring the head temperature, is because the way you are trying to cool the engine through the oil, is distinctly different to the way the engine was designed. There is only so much heat in the oil, and the removal of that heat does not guarantee that the head will not cook.

 

[Kyler]

cylinder head temps

cylinder head temps

Cylinder head temps were 397 in practice 1 and 411 in practice 2. DNF race 1.

Oil seems to be cooler and I assume this because the temps are not spiking as soon meaning exceeding the limit of my inaccurate gauge.

We ran pretty hard too. I was bouncing off the rev limiter this year. Time for a smaller sprocket.

 

[Guest]

Cylinder head temps were 397 in practice 1 and 411 in practice 2. DNF race 1.

Those seem quite high to me. Does anyone know what is a typical head temp for these air cooled motors? Is this data from a spark plug washer thermocouple or a different sensor?

Oil seems to be cooler and I assume this because the temps are not spiking as soon meaning exceeding the limit of my inaccurate gauge.

How long did it take to run off the gauge? In your OP you said 4 laps previously. I am surprised the temp is still that high with the ducting. What were ambient temps? Humidity? Where is your gauge taking the reading from?


Mark

 

[posplayr]

Those seem quite high to me. Does anyone know what is a typical head temp for these air cooled motors? Is this data from a spark plug washer thermocouple or a different sensor?




How long did it take to run off the gauge? In your OP you said 4 laps previously. I am surprised the temp is still that high with the ducting. What were ambient temps? Humidity? Where is your gauge taking the reading from?


Mark

200-220 degC (392-428 degF) is about what I read off of my 1166 header (thermal couple strapped to header and data logger)at 6" from the exhaust port.

 

[Guest]

200-220 degC (392-428 degF) is about what I read off of my 1166 header (thermal couple strapped to header and data logger)at 6" from the exhaust port.

That I will believe with no problem. I once saw color (ie - dull red) on the header just outside the head on my '86 GSXR750 after a spirited run at dusk. That indicates the outside of the header tubing was approaching 800F.

Hopefully we can get some data from someone with a spark plug thermocouple as a reference point.


Mark

 

[posplayr]

That I will believe with no problem. I once saw color (ie - dull red) on the header just outside the head on my '86 GSXR750 after a spirited run at dusk. That indicates the outside of the header tubing was approaching 800F.

Hopefully we can get some data from someone with a spark plug thermocouple as a reference point.


Mark

A little discussion on he topic.

http://www.ebay.com/gds/CHT-Gauges-for-Air-Cooled-Engines-/10000000007206732/g.html
http://www.ulpower.com/engines/faq/monitor-cht-egt.html

On the second link it shows CHT much lower than EGT. It suggests without an external oil cooler the CHT is pretty close to steady state oil temp. At least not 100 deg above.

http://xlforum.net/vbportal/forums/archive/index.php/t-50006.html

This link suggest 400 deg F as an absolute maximum and that the oil temp and CHT are only remotely related. The bigger the oil cooler the more this is true.

 

[Kyler]

How long did it take to run off the gauge? In your OP you said 4 laps previously. I am surprised the temp is still that high with the ducting. What were ambient temps? Humidity? Where is your gauge taking the reading from?

It is a spark plug washer thermocouple on the #2 cylinder.

Ambient air was 86 with 88% humidity. I didn't top out on temps till the 5th lap. The rev limiter is set at 9,000 RPM and I was bouncing off it a lot (more sprockets on order with 2nd day delivery - race again this weekend at the same track). The motor was getting flogged hard.

 

[Kyler]

200-220 degC (392-428 degF) is about what I read off of my 1166 header (thermal couple strapped to header and data logger)at 6" from the exhaust port.

off the header and not at the plug? hmmm. Isn't EGT hotter at the exhaust due to post combustion?

 

[Kyler]

a new oil thermocouple was in the mail when I got home. It came from the same folks that make the gauge. I also got a 1/8" NPT weld-in bung for my adapter which is just visible in front of the left knee tray in this picture. Last time I swapped the thermocouple I noticed the threads were a bit soft and I'm worried about stripping it out. I wish I had installed a bung when I made it instead of just tapping the tubing wall. Oh well, live and learn. Not sure if I have enough time to get this fixed and the new thermocouple installed before I race again this coming weekend. I'd really like honest oil temperature readings.

 

[Kyler]

Here's the latest oil sample report

 

[posplayr]

off the header and not at the plug? hmmm. Isn't EGT hotter at the exhaust due to post combustion?

Yes very much so. My measurement is suggesting your head is running as hot as the hot part of the header pipe on my 1166. In other words you have reached the diminishing returns on oil cooling. You need more air across the motor to cool it down.

 

[Kyler]

I finally found time to install the new thermocouple and it seems to be accurate. It at least shows ambient temp when it comes on.

I relocated the oil filter but am running out of time making new ducting. Next race in 2-weeks at Summit Point. If nothing else, I'll be using my period-correct political signboards as ducting.

 

[Guest]

I finally found time to install the new thermocouple and it seems to be accurate. It at least shows ambient temp when it comes on.

Good deal. If you want to check it at higher temps you can place it in a pot of boiling water and see what you get for a reading.


Mark

 

[posplayr]

Good deal. If you want to check it at higher temps you can place it in a pot of boiling water and see what you get for a reading.


Mark

This temp gauge is accurate only when mounted in certain places.

 

[Kyler]

I moved the oil filter to the right side of the motor to get it out from in front of the cooler. I should have put it there to start with. The new locatiuon will make it much easier to change the filter.

and another view

then, using period correct political signs, I enlarged the ducting.

and from the back side

If this works as expected, I'll get with a buddy who has sheet metal tools and we'll bend up decent ductwork.

After countless hours of research, I believe Nessism has it right, temps should run closer to 180-220 F. With the new thermocouple I'm hoping to see temps in that range next weekend.

 

[qcktvr]

Hi Folks, I have been following this thread with interest, had a feeling that you were worrying too much about your oil temps and trying to get them toooo low, so went looking for some facts relating to the subject; found this which I think puts a few myths to bed:
http://www.speedtalk.com/forum/viewtopic.php?f=1&t=31363
A dry sump system would be nice, although no doubt costly and add weight, but it would eliminate any pick up problems from cornering G forces and let you carry more oil, which would extend the time / laps for it to reach the peak temp.
Anyway, this article makes running upto 300F a few times over a couple or more race weekends look not too worrying.. (and will let you select a good oil).
Now trying to get more air over the motor.... probably a v good thing to do
Wishing you an enjoyable and safe racing season