Thermal Imaging of an XS1B

TwoManyXS1Bs

TwoManyXS1Bs

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And now, for something completely different.

Last week I received a SEEK XR thermal imaging gadget that plugs into my smartphone and tablet. So far, it's been great for finding thermal leaks in my home and scouting nocturnal varmints.

SEEK thermal XR.jpg


SEEK thermal image.jpg


So, here's a video thermal image of my XS1B. Outside temp 85°F, oil temp 200°F.

I had the smartphone and SEEK XR plugged-in, and left it ready to go on a table in my carport. After a several mile warmup ride, I pulled in, immediately put the bike on the centerstand, and within a few seconds started taking this thermal video image.


The imager has multiple modes, the one used here shows colors and a centered "spot" that reports the temperature at that spot. Some interpretation and a grain of salt to be used here. As noted by member mrriggs in another posting, taking thermal readings of aluminum parts can be tricky, due to aluminum's reflective and opaque nature with infrared.

In the video, the polished sidecovers appear cool. An interesting phenomenon. Polished aluminum not only reflects exterior infrared and visible light, it also reflects infrared emanating from its interior. Even though the polished sidecovers are too hot to touch, they're not radiating much in the infrared region.

For those concerned about effective engine cooling, take note that polished aluminum covers don't radiate much heat...
 
The "hot spots" you see on the tops of the side covers are just a reflection of the cylinders. A perfect example of the trouble aluminum poses to infrared measurement.

The Oregon Museum of Science and Industry has some terrific hands-on exhibits. One of them that was a real eye opener was a monitor hooked to a thermal imaging camera. There was a mirror and a sheet of aluminum next to it that you could pick up and play with. The aluminum was just a plain as-rolled finish, not polished. Obviously you could see your reflection in the mirror and not the aluminum sheet. However, when looking through the thermal imaging camera it was the exact opposite. You could clearly see your thermal image reflected in the aluminum and there was zero reflection in the mirror.
 
mrriggs said:
The "hot spots" you see on the tops of the side covers are just a reflection of the cylinders. A perfect example of the trouble aluminum poses to infrared measurement...
Click to expand...

Ahh-haa. Yes, I see that now. Thanx, mrriggs.
I can also see a reflection of the brake lever on the right cover.

I can see where this "imaging" could help explain unusual readings with the "spot" type handheld IR thermomenters...
 
MacMcMacmac said:
Put a piece of flat black tape on that cover and do it again, or a small patch of flat black paint...
Click to expand...

Hey, Mac.
OK, the right cover was recently polished, with fresh black paint in the recessed lettering. Took another look, and, whattya know, a closeup of that cover reveals the higher emissivity in the lettering. Its greyscale would put it in the 200° zone.

XS1B-Thermal-side02.jpg


MacMcMacmac said:
... The cover is radiating heat just fine, the problem is emissivity...
Click to expand...

Now, that's a thinker.

I used to pose this challenge to cohorts:

Take 3 identical bars of aluminum, roughly 1" wide, 1/2" thick, 6" long.
On all sides, paint one white, one flat black, mirror polish the third.
Insert a temperature probe in each.

Summer, high noon, full Texas sun.
Place each bar out in the sunlight.

After 10 minutes, take a temperature reading.
Which one is hottest?
Which one is coolest?

After 3 hours, take another temperature reading.
Which one is hottest?
Which one is coolest?

Why?


This thermal imaging is certainly a learning experience...
 
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Um...so what's the conclusion then 2M ? does a Polished aluminum surface reflect less heat or is it that it is reflecting the IR beam???
.... that video clearly shows Hot spots on the top of both side covers that SHOULD NOT BE THERE...so I expect they are Reflected immage of the cylinders that are 90 deg to it.... and sense their polished Nicely that makes sense !
as MrRiggs said .... though if unpolished aluminum acts as a Mirror to IR.... then it's going to be allot of ambiguity when reading IR on an aluminum engine eh ???
.....
Following your First thought I was thinking perhaps a Rough surface ( like sand blasting) the side covers would disipate heat better....but now I'm not so sure ! .....
....Very interesting ! Thank you !
.....
Bob.........
 
Ok professor, I submit,
At first,
Hottest.....Flat black, the lowest reflectivity and the most heat absorbent color.

Next hottest....white, certainly better than black because it is more reflective.

The coolest....mirror polish because it would reflect the most rays, much like , well a mirror.

After 3 hours I would think they would be more closely aligned , temperature wise, due to heat soak.

So what do I win? Haha!
 
Interesting 2M I always read your posts because I usually learn something.

Two things come to my mind:
Electric Infra red area heaters use reflectors that are flat black and have a slightly rough texture similar to bead blasted engine cases.
During the home work you set the class I read that most of the heat dissipation from an air cooled motor is from convection rather than radiation and that emissivity (and accuracy of thermal imaging) is improved by painting regardless of colour.

Where is your enquiring mind headed next?
 
Ok I admit being set back on the word emissivity ! so I followed the link above and coppied a bit of text to explain it here.....
......
All objects at temperatures above absolute zero emit thermal radiation. However, for any particular wavelength and temperature the amount of thermal radiation emitted depends on the emissivity of the object's surface. Emissivity is defined as the ratio of the energy radiated from a material's surface to that radiated from a blackbody (a perfect emitter) at the same temperature and wavelength and under the same viewing conditions. It is a dimensionless number between 0 (for a perfect reflector) and 1 (for a perfect emitter). The emissivity of a surface depends not only on the material but also on the nature of the surface. For example, a clean and polished metal surface will have a low emissivity, whereas a roughened and oxidised metal surface will have a high emissivity. The emissivity also depends on the temperature of the surface as well as wavelength and angle.
.......
so this is saying that say if you had 2 side plates one polished and one sandblasted and painted flat black that the sandblasted and painted side plate would transmit more heat than the polished one because it's emissivity is higher..... i.e. it radiates more thermal energy than the other.
........However sense we are dealing with scientific terms here the term More can be very misleading ...How much is More ? they don't say
just a number between 0 and 1 and nothing about the amount of heat transferred .... i suspect it would barely be noticeable with an oil temperature gauge ..... that being said.... I simply do not know !
.....
interesting indeed !
.....
Bob.............
 
Many IR thermal imaging devices come with charts of correction factors to get the true temperature of the surface being measured based on the type of material and surface finish. Two surfaces can be at the same temperature, but the readings may be different due to different surface emissivities.
 
Mailman, very good, you got the first half test correct.

You win a cookie.

After the extended sunlight exposure,
The white will be the coolest,
The polished will be the hottest.

The pieces will warm up until equilibrium, when the amount of heat getting in equals the amount of heat shed.

The black will let the most radiant heat in, and will shed the most heat, and hits equilibrium at a high temperature.

The white will let much less radiant heat in, and will shed lesser heat, but hits equilibrium at a lower temperature. This is why most airplanes are painted white. Especially important for fibreglass/composite aircraft.

The polished piece will admit very little radiant heat in, can be less than 1% of the radiant heat exposure, if polished well. Most is reflected away. However, the same happens to the heat trying to escape, it gets reflected back inward, trapped, very little gets out. So, it has to get very hot before its miniscule emissions can balance the entering heat, and achieve equilibrium. Grab a chromed door handle after it's been out in the full sun...
 
so ...sand blasted and painted flat black would allow our XS650's to run cooler in the hot summer sun ????????
.....at least until equilibrium is reached.... so there is a time thing.... otherwise it doesn't matter sense their all aluminum they will all radiate the same heat .......
the question is what can we do to improve the cooling of the hot aluminum engine ?
.....
Bob......
 
Signal, glad you're enjoying this. I'm still learning here, too.

Radiant versus convective.
Painting versus bare.
And, Bob, polished versus sandblasted.

All good questions. Much discussed here before.

http://www.xs650.com/threads/a-bit-of-history-pops-yoshimira.31774/

http://www.xs650.com/threads/painting-the-engine-potentially-affecting-cooling.40355/

http://www.xs650.com/threads/xs650-cooling.43778/

The thing about painting is that you may improve the emissivity, but at the cost of increased insulation, the paint forms a blanket. Which one wins? Search "Kal-gard".

Also, search: "Engine paint" (titles only).

Bob, sandblasting should significantly improve cooling, by utilizing the increased emissive radiant properties of pointed and sharp-edged surfaces.

Signal, the contest between convective versus radiant. Dunno, tough one. Much more energy can be in the radiant component, but you need high temps to get there. The convective is limited to the air temps, airflow and air quality. I'm sure that this has been studied for over a hundred years, but I don't have any hard/fast facts.

You can take a piece of steel and heat it to bright red. It's initial stage of cooling will be mostly by the radiated emissions, overshadowing the convention of the surrounding air. After a time, and at some temperature, its emissions will reduce to a level that is less than the convective component. Where that occurs, and what variables are involved, is beyond me...
 
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Exactly 2M ! the problem is as I see it , we like the Pretty shiny surface ! polished up Aluminum looks like chrome !!!! and it's down right gorgeous ! .... OUR machines work on Convection , shedding heat to the air... hence, the large surface area of the fins.... more surface area more cooling.... sense heat is the all time enemy of air cooled engines it would be better if we INCREASED that cooling where ever possible
weather it be by sandblasting and roughening up the surface of those shiny side plates or by cutting shallow grooves in them say 1/32" deep and making the whole side plate a cooling fin .... replacing the tappet covers with Finned covers is a no brainer here as is a external Oil cooler..... because when Oil reaches temps above 200 degrees impurities in the oil burn up and that is what discolor your oil... it's COOKED
this brakes down the oil and it's viscosity ( thickness) is effected and thinned out.... that is a bad scenario thinner oil means more metal to metal contact on the spinning parts and ware is a result.....
there are 2 ways I know of about combatting this,
1. thicker oil
2. add cooling capacity
most people do both changing from 10-40 to 10-50 oil is a start but I say take it further so your motor lasts longer 20-60 is in my mind better by far.....Valvoline 20-60 racing oil is the oil I like but I don't have any now in any of my engines as it got very hard to find a while back.... I think it is available now though.
I cannot begin to tell you about the importance of OIL coolers ! they are worth their weight in gold and will reduce engine temperatures in an air cooled engine by quite a bit..... these tiny things they have for add on's for our xs650's however I am not sure their worth the effort as they need to be as big as possible !
adding Oil volume helps as well especially if you went to all the trouble of installing an oil cooler....
..... other than that the best bolt on things for adding Cooling capacity to your engine are increased Oil sump size, finned tapit covers and
finned covers where ever possible.
....
this is THEORY folks I have only done a small amount of this so I cannot say for a fact that it is the way to go on the XS650 but I expect that it is !
i feel so strongly about this that, if I had the money I would already have added these things to my machine but alass I do not !
.....
Keeping that big twin cool in the summer heat is important, do not underestimate it's importance ! you boys with fresh rebuilds should watch your temps very closely in this heat, as they may well seize up on you !
....
Bob............
 
I like chrome and shiny too much. Industrial surfaces generally turn me off, but I've seen some tastefully done work on some V-twins (Exile Cycles).

I have a vintage set of large fin exhaust clamps, for the other bike. Should help with head cooling in the exhaust area.

I'd like to come up with a stealth oil cooler, hide it somewhere.

The sump cover is fair game...
 
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