Oil Temps Again

[GregT]

Same here; one race down and 6 to go. My plan is to drop a GS1100 motor in it over the winter. I've saw a lot of GS1168 motors on the Phillips Island entry sheet. What is the URL of the NZ sidecar club? I might be able to get more ideas from them.

Go onto Kiwibiker forum - racing section, look for the sidecar racing thread.
Jellywrestler who is a member on here is one of the four or so guys who certify sidecars for racing in NZ and would be worth contacting too.
There is a quite a lot of trans tasman racing done so the guys on the sidecar thread will tell you what they know.

[GregT]

Uhhhhhh not sure that I can accept that even on face value.

At a given speed and altitude, aerodynamic drag is principally a function of shape factor. A flat plate Cd is approx 1.2. A square van with doors open might have a Cd somewhat above 1, I suspect the Cd of that faired trike is quite a bit lower than 1.0. A reasonably aerodynamic car these days is like .35, so I would guess that bike is probably no worse than 0.75.

Horsepower required to achieve a specific velocity is proportional to the Cd times the cube of velocity. So by a natural process the design probably evolved to one of much higher efficiency that the van, part of the reason for the closed off engine venting.

Frontal inlet drag is going to be largely a function of area alone (ignoring flow out of the cooler.) , but I suspect overall engine cooling efficiency is very much dependent of whether that are is allocated to engine air flow v.s. cooler air flow. That optimization is something that I doubt has been fully explored.

In fact if it was that bad, you couldn't make it any worse by letting some of the frontal area catch some wind to cool the engine instead of the oil cooler.

We're talking specifically classic and post classic chairs - which are a quite different case to modern LCR's for instance. The long bikes are effectively half a formula car aerodynamically.
If you want to see how literally everything can be optimised, have a look at a modern rear engined LCR.
A lot of the classic and post classics don't actually bother with a fairing or trying to streamline anything....why bother on short circuits where you can barely top 100mph ? Better to be able to climb all over the outfit...

[posplayr]

We're talking specifically classic and post classic chairs - which are a quite different case to modern LCR's for instance. The long bikes are effectively half a formula car aerodynamically.
If you want to see how literally everything can be optimised, have a look at a modern rear engined LCR.
A lot of the classic and post classics don't actually bother with a fairing or trying to streamline anything....why bother on short circuits where you can barely top 100mph ? Better to be able to climb all over the outfit...

OK, with this in mind, you are making a strong argument that better ducting for engine cooling, should have little effect on a poor aerodynamics shape. My point being that no matter where the ducting is, it's effect on drag is similar, in an aerodynamically inefficient design it is probably of minimal overall effect anyway. So perhaps the design is better served by more engine ducting or at least not oil cooler ducting to the exclusion of the engine cooling.

The whole bottom of the failing is wide open, I suspect an opening in the cone of the nose would do wonders for engine airflow and probably reduce the head temperature even if the oil temp is already low from forced air flow though the cooler.

[Kyler]

once I have the oil at a temperature I like, then I'll look at the cooling of the motor. The pic below is pre-paint job but there is a NACA duct on either side that dumps on the cylinders.

[posplayr]

once I have the oil at a temperature I like, then I'll look at the cooling of the motor. The pic below is pre-paint job but there is a NACA duct on either side that dumps on the cylinders.

Compare those two side ducts in terms of projected opening area that of the cooler's projected area. Also consider what Mmattockx described before, about an expanding duct.

Air entering a duct with increase cross sectional area will slow the velocity, presumably increasing cooling efficiency through the cooler.

Those side ducts are doing the opposite compressing the flow and increasing the velocity probably running right past the air around the engine.

Following Mmattoxks suggestion if you glassed in a cone shape into an opening in the nose you would get exactly what the doctor ordered. Small inlet, with expanding cross sectional area.

The more I look at that nose it is really just like a big expanding duit. Just cut the nose straight off. Of roll the corners a little so it is not such a knife edge.

Originally Posted by mmattockx View Post

Ideally the inlet hole area is quite a bit smaller than the cooler area and the ducting smoothly expands from the inlet out to the cooler. This slows the air down and lets it recover pressure before passing through the cooler fins, then the exhaust air should be ducted smoothly out into a low pressure zone. .

[GregT]

OK, with this in mind, you are making a strong argument that better ducting for engine cooling, should have little effect on a poor aerodynamics shape. My point being that no matter where the ducting is, it's effect on drag is similar, in an aerodynamically inefficient design it is probably of minimal overall effect anyway. So perhaps the design is better served by more engine ducting or at least not oil cooler ducting to the exclusion of the engine cooling.

The whole bottom of the failing is wide open, I suspect an opening in the cone of the nose would do wonders for engine airflow and probably reduce the head temperature even if the oil temp is already low from forced air flow though the cooler.

i'm not making a statement about how the ducting affects aerodynamic shape at all - i'm pointedly avoiding the argument...

What you've got to realise is that the argument is academic as THE OUTFIT MUST MATCH CORRECT PERIOD APPEARANCE. Sorry to shout but i'm a long way away...He can't do very much at all to improve it - either areodynamically or in cooling efficiency - without incurring the wrath of the dreaded eligibility committee. He's stuck with what has provably been used in the relevant period.

[Grimly]

Ok, what about retaining the nose shape but making the necessary pointy bit out of mesh/expamet?

[posplayr]

i'm not making a statement about how the ducting affects aerodynamic shape at all - i'm pointedly avoiding the argument...

What you've got to realise is that the argument is academic as THE OUTFIT MUST MATCH CORRECT PERIOD APPEARANCE. Sorry to shout but i'm a long way away...He can't do very much at all to improve it - either areodynamically or in cooling efficiency - without incurring the wrath of the dreaded eligibility committee. He's stuck with what has provably been used in the relevant period.

We OK I admit, I have no idea of what the issue is but it certainly does not seem to technical. That is coming out load and clear.

For example, If OP were to put scoops up under the fairing to pull the air that is traveling below the fairing up on the engine area, I would imagine cooling would be greatly enhanced. Buts, I would also appear that that would have so much visual impact so as to not have a "CORRECT PERIOD APPEARANCE".

Of course aluminum foiled oil cooler ducting in period correct political signage is perfectly legal Maybe OP can put a peltier, on the oil cooler, so the electrical load is increased lowering the cooling problem from the shunt R/R. Now that is starting to make a lot more sense.

[Kyler]

I'm not touching any ducting other than the oil cooler for now. One change at a time.

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

[Grimly]

I'm not touching any ducting other than the oil cooler for now. One change at a time.

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

Well, you might find your head temps are ok, but if your oil's hitting over 302 and off the gauge, I kind of doubt it.
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.

[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.

[mmattockx]

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.