Black Intercoolers - Mythbusting Mighty Car Mods
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- เผยแพร่เมื่อ 5 ก.ค. 2014
- Should you paint your intercooler black?
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Does it help to paint your intercooler black? Will painting your intercooler black increase your cars performance? No, it will not. The guys at MightyCarMods have made a fantastic (no sarcasm, it's a great video) video explaining why you should paint your intercooler black. The information they provide is great, but the conclusion is wrong. Let's take a look at why.
Mighty Car Mods Video
• Black Intercoolers Myt...
Related Videos:
Intercoolers - • Intercooler - Explained
Cold Air Intakes - • Do Cold Air Intakes In...
How could heat rejection by convection be improved by adding an insulating layer? The real answer? It can't. For those of you who haven't checked out the video, it's fascinating and I highly recommend it. It's actually a great video, and a well performed test, but it ends with the wrong conclusion.
Lets talk about radiation and convection for a moment, and why one might think they should paint their radiator black. It all comes down to emissivity. Emissivity (on a scale of 0-1) is the rate of radiation that can be emitted from a surface. In simple terms, how much heat it gives off through radiation.
Aluminum Foil: E: 0.07,
Black Paint: E: 0.98
The higher the number, the higher the rate of radiation. Blackbody, which has the highest rate of radiation, has an emissivity of 1.
Black bodies give off the greatest amount of radiation. So one might think that making an intercooler black would improve it's performance, because it would give off more heat. But this is not the case, because intercoolers are not designed to dispose of heat via radiation, but via convection.
Radiation: Does not rely on movement of molecules.
Convection: Does rely on the movement of molecules passing by the hot/cool object which is giving off heat.
Electronical Stig is correct in his statement that emissivity does not have to do with convection, but intercoolers are designed to work off of convection, not radiation! Why? For starters, because your car moves. That's also why your radiator has a fan, for when it's stopped it can supply airflow through it.
If the outlet with no paint has a dT of 100, and the outlet of the black intercooler has a dT of 97, the intercooler with no paint is rejecting more heat. This means the air inlet temperature of the engine will be less for a non-painted intercooler!
In the MightCarMods experiment, the fan was very far away from the intercooler, meaning airflow was actually quite low. I would imagine as the fan gets closer, the difference in temperature between the black and sliver intercoolers would widen further. Intercoolers are designed for convection, not radiation. If your car is moving, your intercooler is going to provide you better performance with minimal insulation.
There is not a single car manufacturer which comes with a black intercooler stock (to my knowledge). Is this because they don't understand emissivity or how to design an intercooler? Is it because this a new secret and now the industry will suddenly change? Absolutely not. Some of the most brilliant minds are behind automotive engine design, and the reason intercoolers are not painted black is because intercoolers are meant to reject heat via convection, not radiation.
Disadvantages:
- Insulation, hinders convection by adding an additional layer which heat much travel through, prior to being rejected
- More restrictive, decreases airflow through the intercooler, preventing proper convection
- If the intercooler is exposed to sunlight, which many are (especially with removed bumpers), the black intercooler will absorb a lot of the heat, where as the aluminum intercooler actually does a very good job of reflecting the heat.
- Other hot objects (exhaust manifold, engine, turbo, etc.) will put more radiation into the intercooler if it is painted black, heating up the intake charge.
- WARMER AIR INTAKE TEMPERATURE
How much you're going to decrease your performance by is highly dependent on many factors. In many cases, it may be a small difference, and not worth noting. The major point is, you will not see an advantage from painting your intercooler black, unless your car never moves, and you don't use convection for cooling the intake charge. Unfortunately, or fortunately, your car moves, and it cools the intake charge using convection, so the conclusion: do not paint your intercooler black.
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Starts watching video about painted intercoolers, learns why polar bears don't get cold in the wind
+RoyalSilver&Gold Can I borrow this please?
+RoyalSilver&Gold Brilliant!
+logan buck if only other people realized the same works for dogs, so they dont need to freak out when they see dogs out in someones yard on a winter day. Many dogs (especially ones with thicker fur) prefer to be outside to cool off.
And polar bears are painted black, so they absorb more of the sun light - the fur is actually channeling the light onto the skin. Polar bears are so cool on many levels!
Multitasking 😁
Great video man. Very enjoyable. And I think we almost came to the same conclusion, that with airflow there was a negligible difference. But with no airflow, we saw, and measured a significant difference. We stand by the results we achieved on the day, though we can't be sure how the results will apply to each persons circumstance.
One important point and comment is that you stated that car manufacturers don't make black radiators and went on to say "Does this mean major car manufacturers don't understand emissivety?" But a huge amount of cars do have black radiators. It would be interesting to know why?
We're really glad our original video has inspired a lot of debate, conversation and education - it's exactly why we do these kinds of videos. You should jump onto the MCM forum and add to the discussion. There's a 10 page thread on this topic already. Hopefully we'll see you there! Cheers!
Mighty Car Mods I was hoping you guys would show up! :D I was thinking throughout the whole video about how he doesn't mention the advantage in no airflow. For me, a commute with stop-and-go traffic, I see an advantage, and will be painting it black on my Subaru when I get the time to dismantle the thing.
Lol you stand by the results I just lost a whole lot of respect for mcm he explained radiation and convection theres no point in having a cooler intercooler if you not on boost/ not moving
Like come on at least have the balls to say your conclusion was wrong....
Jeremy quiring It's not all about power, turbocharged cars are very fuel efficient. A smaller motor can make the power of a big motor, but only when needed. Sitting at idle or low speed with a lower intake temp is a benefit for my fuel economy, as my engine can use even less fuel to maintain enough power to idle. Also, in a drag race, staging (vrooom popopopopopop) a turbo car can see benefits on the line from a cooler intake temp. Just depends, clearly there are advantages and disadvantages to this mod. Decide for yourself what your car might need.
I respect both youtube channel but I don't know who to trust. Mighty Car Mods need to DYNO the Sliver and Black Intercooler to back up their claims with more empirical evidence.
Wood floats on water. Ducks also float on water. Therefore ducks are all made out of wood.
Nice reference
basic logic principles. i love doing this in arguments
Monty Python at their best.
What about small rocks?
Video is correct! Stop insulating your heat expelling components!
Best finish would be clean/polished aluminum.
Next best finish (it won't look corroded in a few months or corrode and crack/fail in areas where water/dirt/salt can collect in the fins) would be anodized aluminum as while anodizing is also insulating, it is far far thinner than any kind of paint (and also lighter BTW).
It is also very hard and abrasion resistant.
Read up at en.wikipedia.org/wiki/Anodizing under 'Sulfuric acid anodizing (Type II & III)'
'Type II Coatings of moderate thickness 1.8 μm to 25 μm (0.00007" to 0.001") are known as Type II in North America, as named by MIL-A-8625'.
Yep - as thin as 7 one hundreds of 1 thousands of an inch (or 7% of 0.001" - difficult to measure) up to one thousands of an inch of an aluminum oxide layer that can be uniformly and consistently be coloured (BLACK? or a hundred other colours - RED perhaps?, or just natural aluminum - the colouring won't effect final coating properties except for the MAAAD results) in the anodizing process (colouring won't change the thermal conductivity).
I've had a few VW (1983 to 1997) and the aluminum rad cores have NEVER failed. The joint between the AL rad core and the thermoplastic end caps has always been the point of failure.
Problems - anodizing is a thermal and an electrical insulation so modifications (welding on/fixing brackets) requires a bit of grinding/sanding to remove the anodizing in that location (same as you'd remove paint in that area) which ruins the anodizing in that area.
Aluminum pop/beer cans have a total PAINT thickness (inside and out) of about one thousandths of an inch (25 μm - pretty good and uniform but not abrasion, corrosion weather resistant). Anyone with any kind of spray on paint will NEVER be able to provide a consistent thickness of paint over the huge area of the inter-cooler 'tubes' and paper thin fins as it is nearly impossible to paint the deep recesses created.
Paint sticks much better to an anodized AL surface than a bare aluminum surface unless using a specific bare AL primer (ANOTHER layer of paint - the primer - is counterproductive for heat transfer).
Absolute best - car that never sees anything other than the track or lives in a desert - BARE ALUMINUM.
Next - Anodizing AFTER all bracket modifications, etc have been performed.
Next - anodize all over, tape off the inner part of the inter-cooler (inner tubes and fins) and spray paint the OUTER surfaces of the inter-cooler.
Blows me away that anyone would think that painting something black would help cooling. If you want a better intercooler put away the rattle-cans and go air-to-water. I thought the original idea behind painting intercoolers black was to help hide them in sleepers.
nearly ever electro motor is painted black due to higher radiation
John, 100% correct. I gave mine a wafer thin black dusting only for the stealth look.
As an engineer you have no idea how good to hear someone
1) Make sense
2) Explain and recherche and back up his idea with ACTUAL real knowledge....
3) I love that book!!!
4) Thermo at work!!!
Jamal Chehab Woo!
i hate that book
Jamal Chehab lol finals exam on thermo next week, wish me luck
Recherche, thw covfefe of engineers.
"A hot sunny night...." Ah, I often have those where I live.. Lol
I came here to comment the same thing!
i was about to say, "is that a reference to a inside joke concerning fireworks?" lol
+sean25351 sorry you're having such a miserable day you gotta take everything the wrong way. hope it gets better for ya!
+sean25351 yeah I'm sure that's what happened. piss off.
+D Stingray summer night... you dumbfuck
If you were a teacher in my science class, when I was in school, I would've enjoyed it a lot more. You're awesome at giving information in a way that it's fun to pay attention and learn. Thank you for doing what you do
Amen!
No good teacher teaches..they got much better jobs..lol
OhighO Skater : Agreed! He's awesome for knowing and sharing all kinds of stuff we want to know. Potential youtube god status
@@ryanwells5035 Also agree, which accentuates the fact he's awesome for taking the time to make these vids
I would be bored to death in his class of babbling!
"HOT SUNNY NIGHT" LOL
I think they call that "day"
@@inufreak483 that depends on where you live, if its light at midnight is it day or night?
@@jaydunbar7538 You're right! If you're far enough north, it doesn't get dark in the summer, that's why Yukon is called the land of the midnight sun.
"then why do you have a campfire"
I thought I heard wrong!lol
I'm not a mechanical engineer and I thought painting the intercooler black was obviously going to yield worse performance. Good video though - I wasn't expecting to learn as much as I did, and you did a great job at proving someone wrong while being perfectly humble about it.
As a very well read ex-physics student gone machinist, I would like to add 2 very important points to Engineering Explained's video. Normal black paint has a high emissivity in the VISIBLE spectrum. A car intercooler never gets hot enough to emit radiation in the visible spectrum! It is highly unlikely that whatever black paint is being used is 'black in the infrared' too - the intercooler will only emit radiation in the infrared, hence the idea of using black paint is a moot point from the beginning. You would want a coating that has an absorption spectrum from 700nm to 1mm lambda. Point 2 is something you never went over, and that is why their intercool was more efficient without airflow with black paint than without paint. The answer is simple: The solvent in the paint must vaporize/flash off in order to dry. When this is happening, there is a phase transition from liquid to gas, which absorbs heat from the immediate substrate (the intercooler) in order to accomplish the phase transition. THIS is why the intercooler was cooling so much better at first with the black paint and no air flow! The paint drying was sucking the heat off of it!
+DjRjSolarStar Indeed, the only way they could have been so wrong in their results is if they ran their 2nd 'test' before the paint was completely dry. Evaporative cooling FTW. Moral of the story: Mechatronics engineer should stick to mechatronics.
Now, we have the complete picture :) I'll copy/paste your post so others can read it.
DjKinetec ok
DjKinetec nice! So paint the intercooler silver just before you hit the drag strip lol. Love it, though!
@@WadeOntheLure I get the joke :) But on a serious note you can spray water on the cooler to increase the efficiency.
345 people have painted their intercoolers black
They idiots
Actually most Montune and Cobb intercoolers come with some portion of black, Montune is completely black. These companies actually employ ME's with automotive backgrounds. This is just like buying a shirt in the hot summer, you can go with the white Hanes tee-shirt or a identical tee-shirt made the exact same but is dark blue with the Hoonigan slogan on the the front. You will pay more money for darker Hoonigan shirt, since it's the same shirt you are paying for a logo and the Suns heat will heat up the more expensive shirt. It is all in branding and what people think is cool. Intercoolers are ultimately made of raw aluminum, but can sell an inexperienced modifier a black one for an extra 50$, or whatever.
some people paint them black for stealth...
Even companies do it from factory, the new Ford focus RS which makes way more horsepower than any subaru.
The Focus RS also includes a plate to make the intercooler even less efficient than just painting it black. Therefore all intercoolers should have blocking plates? Being an owner of the Focus RS, I'm here to tell you, this car is not made for track driving at all.
3:33 hot sunny night :D
well yes, in the northern hemisphere you get midnight sun in the summer, wich means the sun never sets it happens here in the northern part of sweden.
DyingCr0w Here in Finland.
NJHS92 uhhhh... “in the northern hemisphere”. No.
In the Arctic circle.
But not just that, same thing happens in the Antarctic circle.
Colin Griffin well technically, the sun is out even at night. Unless it's a full moon (or new moon? Can't remember which one is pitch black lol) as the moon light is simply just a reflection of the sun's light lol. Same way as you would say "he pointed a laser at my eyes" even if it wasn't laser to person, but rather laser to mirror to person.
Ummmm...... the sothern hemisphere is no different, just six months offset. ;)
OK, after watching the MCM video I think I figured out why they got such an improvement from painting the intercooler (during the no fan test). It's because the the intercooler is covered in fresh paint. (they even made a point of putting a ton of paint on the thing) And that paint is still evaporating it's solvents. So it is not just giving off heat by radiation. It is also evaporating, and of course there is some airflow due to convection. Given enough time to cure, a week a month... the advantage of the fresh paint will disappear. And the 3% gap seen with airflow will widen.
Oh, and of course, painting the intercooler black does not eliminate the original surface of the intercooler. It's still there, and must now transmit it's heat to the paint.
I can say with first hand experience that major automotive manufacturers do in fact paint intercoolers, radiators, and condensers black. Its 100% for looks. You are correct that this does slightly diminish the returns of the heat exchanger, the parts are generally designed with this in mind. Also, when paint is applied, its done in a very thin layer to reduce the loss in efficiency, and to not coat the inner portions of the fins or tubes where most of the surface area is. So yes your right that its better to leave the metal bare, but the losses shouldn't be significant due to a light coat of paint.
Source: I work for a major OEM parts manufacturer where these components are made and some are painted black as well.
Awesome, thanks for sharing!
One of the best channels out there. Love seeing this stuff since I'm currently in Heat Transfer class.
thanks for doing these videos, your explanations are always easy to follow
2 minutes of silence to those who painted their intercoolers black.
Mads Filholm well the difference is very small between the 2 so if they did it for design probably it worth it I guess.
Here is a challenge; see if you can spot a black intercooler in any form of motor sport ? Or any OEM ? No, I didn't think so.
Nor Dic BA Ford Falcon XR6 Turbo
Nor Dic
89-03 (1st and 2nd gen 12v Cummins add 2nd gen 24v) are aluminum supplyed to dodge painted black...
I have a 91.5 that is tore down to receive an 03 IC both stock black. I guess this makes Cummins/ Dodge a minor OEM ... I'm in agreeance shame on them for having painted these black.
Ford Focus RS also uses a black intercooler. Even if the difference is negligible it does look pretty cool.
When I finished watching their video a few weeks ago the first thing I wondered was what you'd have to say about their conclusion. You are like a younger Bill Nye. It's one thing to know your stuff but the real talent is making it understandable to non engineers & you sir are awesome at it. I've subscribed for years & keep coming back for more.
Thanks! Bill Nye has always been an inspiration. Like the master himself, I only have a bachelors of science in mechanical engineering. An interesting fact on the guy. I appreciate your viewership!
I love your videos and only just stumbled across this... Best one by far!! Not only did I learn something new, but I saw your humour come out too. Your comment about a Chimp not being as good at explaining how an intercooler works using a whiteboard had me cracking up!! Ha ha ha
Fantastic video. Excellent explanation and even less intellectual people such as myself can understand the HOW and the WHY :) You were very respectful to MCM guys - I go to them for entertainment, ideas, inspiration, encouragement... but the science and the making it work right or for doing something mechanically brilliant, I'm going to look for people like you :) You still provided plenty of entertainment as well though. I like your personality and the way you present things in your videos. Thanks for another great production!
As a fellow engineer I have to say that I absolutely love your videos, you're one of the few YT sources that actually has knowledge of the engineering, physical phenomena and practical knowledge of cars.
I salute you! :D
I already feel smarter and I like the way you set out your vids and how you explain everything on the board.
I also think it will be really cool to see you modifying the integra but with your added knowledge and take on things.
Good luck with furure vids!
"If its a hot sunny night then I dont know why you have a campfire." I died of laughter!
even after 4 years I find this video is still one of my favorites. I even linked it to a thread wherein a vendor was answering me as to why the intercooler (being offered for sale) was painted black:
"purely for looks" was the reply. That's when I posted the link to this video. I suppose marketing trumped science in that decision-making exercise. Always good to learn from someone who brings
science to the discussion.
Great video. I just put a fat Turbo on my Polaris RZR 900 and everyone and their brother says i should paint it black (my intercooler). F that...the first thing i thought to myself was that the paint will act as an insulator and on top of that, mine is in direct sunlight so it would also absorb heat as well. I am not an engineer so if someone like me can figure out that basic common sense, i wonder why others seem to think different? The mighty car mods thing is good to i agree because they are awesome but your's is a more logical explanation of what is happening. Oh, and you just earned yourself another subscriber - thanks!
meade916 Thanks for subscribing! Awesome channel by the way, I've watched quite a few of your videos!
Engineering Explained haha, right on man, good to hear that!!! I appreciate it man and now that i found you ill be watching quite a few of your's! Love your channel!
"I am not an engineer so if someone like me can figure out that basic common sense, i wonder why others seem to think different?"
I am an engineer, and the answer is: Application. For engines that make boost at low rpm, like superchargers or even many modern turbos, the 60% increase in heat transfer at these low rpm and low vehicle speeds can be a boon for the 0-60 and 1/4 mile times. That 3% loss would be an issue on the circuit, however, as the vehicle relies on mid and top-end power.
What say those of the half-brother persuasion @paint?
Engineering Explained i actually ended up painting my intercooler....but not to gain any heat dissipation which i know won't happen. I did it for looks. Even though i am sure some of the paint got inside the fins, we specifically didn't soak the crap out of it and focused on just the outside area so i could get a logo stenciled in. If you look close at it you can see the aluminum inside the core still. So I know i said i wouldn't do it but i mainly did it knowing it probably won't help but also that it really shouldn't hurt much either. I stuck 2 giant fans on the intercooler as well where i never had them before so it should be good to go i think.
Radiators in cars used to be black when they were made of copper. Now they are aluminium they are silvery. Probably because copper needed painting to stop it corroding. The aluminium is protected from corroding by an oxide layer that is increased in thickness by anodising, it would be easy to anodise them black, without any insulating effect if it made a ha'porth of difference. Which it doesn't, so they don't.
Any water or oil cooled engine has no radiator it has a heat exchanger.
@@rustybeatty6567 Whats the difference?
"Conclusion: Do not paint your cooler black."
But I don't want people to know I'm packing.
Deadass lmao
Use a liquid to air chargecooler and you'll be sneaky AF....
I absolutely love your videos. This is quality right here. Thank you for your content
I just got finished testing both of my intercoolers (Twin Turbo side mounts) I left one as is and I coated one with thermal dispersant paint. To those that argue that coating the IC will create a thermal insulator, consider the material you are using...if the coating has a specific heat capacity that is better than the substrate, you will conduct in the direction of the coating. If it is worse than the substrate, you will insulate that substrate. I ran a test similar to mighty car mods but with better controls. Instead of running an ambient fan I built a shroud to activate the intercooler cooling surface (this is equivalent to the car moving). Might Car Mods is hyper-focused on emissivity when there are other factors that cause the improvement in IC efficiency. Without Coating, We heated the intercooler body to 185F. The Instantaneous Peak IC Inlet Temp vs Output temp was 82 Deg F. With Coating, the Delta at the same IC heat soak peak temp was 135 Deg F. This is almost a 40% reduction in temperature! The coating is designed to increase conduction and convection of heat and this simulation depicts conditions of what happens in intercoolers after an increase in turbo boost. The result is that the coating gives one's vehicle a better margin of safety against potential pre-ignition/detonation due to high engine inlet temps. This also means you can run higher boost pressures for better performance. The test setup had thermocouples in ambiet air 5 feet away from the test rig and an additional TC in the fan shroud 5 inches from the IC's cooling fins(inside of the fan shroud). The other 3 were at the IC's inlet, Halfway through the IC cooling fin body (inside of the fins) and the last one at the outlet. All equipment was Calibrated. Equipment used: Degree ATM 2400 and USB UTS100T thermocouples.
Black intelcooler - more effective.
Red car - faster.
Yellow suspension - stronger.
Chrome exhaust - louder
Flame stickers + 10 hp
Fake air vents +15 hp
Polished turbo, +15% airflow
yellow brakes - stronger*****. blue suspension - smoother*****
Surf board size rear wind : Magnetic Traction on 20 mph turns..
dice valve stem: +20% grip
The chimp analogy rocks! I'm still wiping the tears from my eyes! Hilarious. The video content first class as always! Thanks
So happy you did this vid- I had the exact same confusion after watching their vid
Redd's laws of thermodynamics:
1) You can't win (you can't get more energy out of a system than you put in, conservation of energy)
2) You can't break even (Friction, loss, etc. you will always have less energy out than is put into a system, entropic principal)
3) You can't leave the game (Unless we find another universe with completely different rules, and even then it's not very likely that you could circumvent rules 1 and 2 in any universe conceivable that contains matter)
+ReddmanDGZ ok
Your statements are very true and very misleading (not true) at the same time:
- "you can't get more energy out of a system, than you put in" - complete nonsense, we both know that, right? I can trigger a process, using a small amount of energy, for a much larger energy transfer from the environment. Just like a heat pump does. Or a transistor. Or an implosion atomic bomb. The true statement would be "you can't get more energy out of a system, than WHAT'S ALREADY IN IT". Doesn't matter how much you are putting in. The environment could be putting in a LOT more, than you are.
- "you will always have less energy out than is put into a system" - Exactly correct. Notice, how this statement contradicts the very first one directly. In majority of cases, there is an additional energy being delivered from the environment anyway, in the form of heat (infrared), microwaves, x-rays, etc.
- "you can't leave the game"... What game?
@TheRadiastral The energy is already there for those things, you're forgetting that you also put the materials (therefore the mass/atomic bonds) into the system.
finally a good video maker that can actually explain things subscribing
Thanks for subscribing!
np man love the vids I understand everything a lot better now
+Burak Keles what do you mean finally, where have you been, Jason is already a legend.
lol
Your remark on the chimp alone made my "like" :) Love your educational stuff.
You're awesome, man! Love the little smirk at the end. Lol
Great way to clear up the confusion. Love your videos!
Unfortunately they are not right. And their own numbers show that. 97 : 100
^ doesnt understand math
***** You are right. I would prefer 100 degrees. Thus the SILVER intercooler. Thus they are not right in stating that the black intercooler is better and their own numbers show that. ("They" and "their" are Mighty car mods of course. I guess we got confused because my comment was a response to someone saying "but might car mod proved it", which was later deleted.)
Gunfu Brizzo Why exactly?
Since I discovered your channel, I rarely watch other channels based on car modifications.
I enjoyed thermo too. As an engineer I sometimes forget what is such an obvious thing to me (from my education) and not to others. good video explaining. Its funny how often car trends are really bad for performance. Now I gotta go watch mighty car mods to see this.
Just helped two people decide to purchase a silver intercooler over a black one for our VW GTIs, by showing them this video. Great job again sir! Extremely useful info
"If it's a hot, sunny night" Wait a second...
Imagine that 3% at 70mph on the highway! Just a tiny fan produced a temperature difference of 3 degrees C. I would imagine that the amount of air flowing through an intercooler on a drag strip going 90mph would be significantly higher and that 3 degrees would be multiplied tenfold.
Completely agree!
Engineering Explained Now imagine if the intercooler was 30 degrees cooler before it had 90 mph winds blowing through it on the drag strip, you know, because of less heat soak from idling in the staging lanes for 20 minutes...
If the MCM data is correct, then the intercooler will be 30 degrees cooler at the starting line. The air going through the intercooler isn't going to cool it 30 degrees in 10-15 seconds the car is moving down the strip, especially since the car will be at full boost the whole pass.
Not saying your video is wrong, I just want you to mythbust the advantages of a black intercooler reducing heat soak.
cody clark Well, if you think about it this way;
If black radiates but also absorbs heat more easily, the intercooler may well heat soak faster if it is in the engine bay near to things that radiate a lot of heat.
Furthermore, if the air temperature around is hotter than or close to the temperature of the air flowing through it (in the case of the air intake location being cooler air, or air at the same temperature as the intercooler's location), the intercooler will probably not cool the air very much through radiation because it's close to being in equilibrium, the heat wants to flow from an area of high concentration to an area of lower concentration.
In the MCM video the heat soaked intercooler was on a table at room temperature which is basically best-case scenario for allowing the heat to radiate, in a real car the situation is not likely that ideal, being close to hot blacktop and possibly an exhaust manifold.
If, for example, you had a black and a raw aluminum intercooler in the same place on identical cars lined up at the strip (for worse case scenario, think subaru top-mount, or a front mount on a honda that sits very very close to the exhaust manifold and very close to a hot road surface, where the radiant heat will be at it's worst) you would expect the aluminum intercooler to heat soak more slowly because the radiant outside of the intercooler is greater than inside. It would also cool down faster as the car pulled away down the strip.
The only way it would be better would be if it was a very cold day, and mounted far away from anything under the hood that would radiate heat, and also not in direct sunlight. However, that improvement would come at the cost of making the car perform worse in hot conditions and in convection at speed.
I think, anyway. It would be fun to test this with a car like the 300zx twin turbo because it has side mount intercoolers and the turbo system for each cylinder bank is a mirror image of the other, so you could paint one side and not the other.. and test the results.
I agree, but I would have argued with the mcm's results if I hadn't seen the video proving that the black intercooler actually lowered the boost air temps without air flow. I would like to see a test with the black intercooler with higher ambient temps to see if it really does help with heat soak.
Your vids are great, sir. Keep up the good work.
Thermodynamics and fluid mechanics is one of the hardest things we learn at uni, but its definately one of the most interesting! Loved this video
I would say they're the hardest of the core mechanical engineering curriculum. The senior and upper division / elective engineering courses, which build off of the basic principles of thermo, heat transfer, and fluids are way harder.
Should have said "If it's a hot sunny night, I don't know what universe you're living in"
PixelCortex I can't guarantee my words will always be great.
+PixelCortex Or you're in Alaska in summer time.
+Engineering Explained You should do a video explaining how you would have a hot sunny night in which people would be around a campfire.
+PixelCortex I believe a sunny night is called day
+PixelCortex he dosent have to be on a warm universe I guess you havent heard of the places on earth that have sunlight all day ;)
it appears from the MCM video that if you want better performance while stationary then the black intercooler is the one for you!
I believe most people want performance while they're moving. ;)
+Engineering Explained oh there's a market for everything :p .. great channel btw, I've learned lots.
+Matthew Papowski They must wanted it black for that S2000 so when it breaks, it runs cooler on the side of the road.
Well i think stationary performance is often called "swag" or more accurately "looking cool". As the word "cool" suggests, cars with higher stationary performance run cooler all around. Sounds completely logical right?
+Engineering Explained Great video. I understand the Intercoolers & Radiators function - BUT why not have a intertwined radiator built into the intercooler? One water channel, one air channel and so on... OR will the hot turbo air heat the water and thus cause the air to remain hot?
Cengal & Boles- same thermo book I used at University of Portland nearly 20 years ago. Very well done (especially compared to my confusing Shigley machine design book). I remember one of the problems in the book was calculating black vs. chrome cooling fins on an air-cooled motorcycle engine like a Harley (no cooling fan). At speed, convection overwhelmed radiation and made it negligible, but at idle where you have only natural convection, there was a small but significantly useful advantage to the black fins...something like 10% or less. A 10% advantage is important if you're about to overheat in traffic. They probably would've been closer to 10% without the insulating layer of paint.
A black intercooler might slightly help your intercooler while you're stopped, particularly if you anodize it instead of painting it, but it won't make a difference once you're moving so probably isn't worth the effort. Also, it's been a while, but shouldn't you have used absolute temperature?
I love this video! Seriously!
Great video! "the more worthless the system is" LOL I love the side commentary.
A little different take. My old competition drift car (pro am) I painted the back-side of the intercooler and radiator, but left the front side bare.
Drift cars you RAIL on them, then you sit in staging and wait to get launched again; this is where we see immense heat soak issues arise.
Logic behind painting back side, is the frontal (front half) of heat exchanger surface areas remain un-insulated, so where the temperature differential is the highest there is also minimal insulation. On the back side (also in the dark in the engine bay) it is black, this is where we want more radiative based cooling since we aren't moving, and everything is hot from a hard run, now bleeding heat into everything. We want the heat exchangers cool when we get launched so we don't feel a power loss, as this will change how you need to drive.
New comp car, the heat exchangers are left polished for aesthetics, and water sprayers are installed, so when the car isn't moving we can spray water via button onto heat exchangers and allow evaporation to help disseminate thermal energy. (I'm assuming you like this method much more lol) Running Ethanol for fuel which burns colder also helps keeps temps lower. Effective ducting, and division of air channels so heat exchangers don't share air also helps.
Anyway side tracked now.
This reminds me of the guys who argue "hella flush stance" improves their vehicles handling abilities.
"hot sunny night" "i don't know why you would have a camp fire" i lost it over here
Fantastic video, as always. Keep it up!
Dear Engineering Explained, I m a big fan and I seen your channel a long time ago, so first of all congratulations.
And you with MCM that would be awesomeeee!!!
"If it's a hot sunny night, why have a campfire?" I laughed.
For the marshmallows, of course.
To be honest, I think the biggest issue that needs to be discussed in this is ducting and not the painting. 90% of the time I would say lack of proper ducting far greater outweighs the 3% difference in temperature.
I can't even count how many intercoolers that mostly are just stuck in the front of the car and not properly ducted. And that ducting is to be applied on both sides ( air being rammed through the front of the car at speeds, as well as the fan being properly ducted to pull at idle properly.)
I haven't done any testing properly, but I think that should be done in 3 tests though, one with just a fan stuck on there, second one with a fan with a fan shroud bolted on, and thirdly with the fan and shroud sealed with tape or foam tape to ensure all corners are properly air sealed.
Lastly before getting back into painted vs non painted, another big factor that I often see is lots of fins being bent. Even a slight bend can reduce the flow pretty drastically. Its not uncommon for me to see radiators and intercoolers with probably about 10% of the fins bent in ( or actually on the topic of fins, being filled with bugs or dirt and grime) that would far out weight the paint discussion.
Now to get to the heart of the the topic, I do have some issues with "jumping to conclusion " that a painted intercooler, vs a non painted one actually makes a difference. There are lots of open loops here, one there's a big difference in entirely painted (think of it dipped into a paint tank and then pulled out) the other part could be just lightly painted to change the frontal color ( keep in mind , probably over 99% of the non painted surfaces are still bare aluminium. ) One major factor plays here in regards of that and that is core thickness. The thicker the core, the less the percentage of the painted area is in the case of spray painting the front faces to non painted is).
Another angle to consider is age. As the cores age, oxidisation occurs on the bare aluminium. Does this oxidisation layer make the core less or still "more" effective than a painted one that may have oxidised less over the year due to the protection provided by the paint.
... In summary, painted or not, that is the least of any of the major issues to be concerned about in regards of a cooling effect of radiator or intercooler.
But are they wooden duct's.And do they float, Hmm
I worked manufacturing high end radiators and intercoolers for mining equipment (mainly). ALL were painted black before being bolted together with the condenser (and sometimes even fuel coolers, often only seen on the really big rigs used to do outback trucking).
Link really ? No motor sport of any type has black intercoolers.
I really enjoyed this video, it reminds me of watching mythbusters and imagining that it would be a much better show if they had a mathematician or physicist on the team because they sometimes (though rarely) end up testing the wrong thing or getting the myth wrong.
One small thing that confused me a lot learning about thermodynamics growing up is that people talk about convection as a distinct process, like you can have convection without electromagnetic radiation. Radiators are very good at transferring heat to the air within them via radiation, so much so that the air quickly reaches temperatures close to the radiator temperature and now there's nowhere for that radiated heat to go. So good radiators are limited by, not based on, their ability to convect that hot air away, which is why that's the thing to optimise.
Great video. You should be lecturing at Uni (if u aren't already). There is a real knack to being able to explain physics/engineering concepts- well teaching anything really,in general, and you have that knack.
That was very comprehensive. Maybe a little too comprehensive. Since it's a hot sunny night, I'm going to go sit by my campfire now.
Black intercoolers on many 80s and 90s JDM cars - Impreza, Legacy, Skyline, Supra, plenty more. The Lancia Delta HF Integrale too. After the 90s, I can't think of any. Did they get smart or are they doing it for good looks? I don't know.
Though this does bring to mind drilled rotors on new cars.
You do a great job of delineating the the different types of thermal energy transfer such that the layperson can understand that there are different ways that heat behaves.
When you said "Hot sunny night" 3:30 lol
In the arctic circle the sun stays above the horizon 24/7 in summer time. In winter it doesn't go above the horizon, it's dark 24/7. :)
DG At least till the axis turns :)
Excellent video although I don't know anywhere on earth you can have a hot sunny night. You can have sunny night near the poles (if you base night on time of day) but I wouldn't exactly call it hot.
+Nan0Scho1ar just give it a couple more years. ;) It was a joke, also.
Hahaha I didn't even realize, I thought it was just a slip up but it seems the joke went straight over my head. Keep up the good vids :)
I had a sunny night (22:00) in Helsinki recently and it was kinda hot (24 C)
Great vid, thank you so much for walking us through this. I really want to make a nice long video testing aluminum *oxidizers* or whatever we want to call stuff that makes aluminum not shiny silver. I hope we can test the effects on the integrity of the aluminum intercooler, vacuum intake, and charge/intake manifold piping. Thank you!
Factual and funny. Love it, keep it up!
I know this is an older video, but I was wondering if you know why almost all radiators for warercooled pc's (which use fans to cool them) are black? Would this be purely aesthetic, or do you know if there are examples of paint which interfere so little with the air flow that the emissivity of the black paint and the heat lost through this could positively effect rate of heat transfer. i.e a paint so thin that the pros outweigh the cons...
Tom Eiseman good question, I'd also like an answer.
billy653 I can probably answer this. It's the same reason almost all radiators in older cars are painted black. Copper. Copper has been the material of choice for radiators for a long time, but the issue with copper is it readily oxidizes. So manufacturers coat them in black paint to protect the copper for the atmosphere.
Pony Power
Ah good call. I haven't sand blasted a computer rad, I just know all the automotive rads that are copper are painted black.
+Pony Power That's far too fast to jump to a conclusion there. It strongly depends on the manufacturer of the radiators. For example Alphacool is always using copper for their radiators with a really thin black layer on the outside, but NOT on the fins of the rad. (See topic of insulating layers)
So just saying they paint it for hiding bad quality is bullshit and probably only counts for cheap rads where common sense already tells me that a cheap rad will be manufactured cheaply.
Also, Alphacool already sells white radiators. The colour design of those radiators have to match as many PC-builds as possible, else they wouldn't sell enough units and the most neutral colour that in 99 % of the cases fits to any colour-scheme, is black.
lol once I saw the title of this video, I can Imagine Engineering Explained watching the MCM video and thinking: "Fuck... I don't want to have to do this... Seriously? Looks like I'm going to have to bring out the whiteboard"
Haha it wasn't how I planned on spending that day. :)
I knew it didn't quite make sense. Nice one EE, everyone painting their intercoolers needs to see this.
Very informative, but I would also love to know how a heat dispersion coating or paint would help or hurt an intercooler.
Is the effect much different if the aluminium is anodised instead of painted?
That question sort of comes from a slightly different subject, with regard to heatsinks attached to small brushless DC motors, would it be better if the motor itself was anodised black, or painted black, instead of the fancy colours we get in RC cars?
+Skiddins Almost all aluminum used in components (ie: manufacturing) is anodized. Anodization simply adds a very very VERY thin layer of aluminum oxide which acts as a corrosion barrier to prevent the aluminum from rusting (yes, aluminum rusts). The key thing between aluminum and say iron, is that aluminum oxide actually prevents rust whereas iron oxide does nothing for it. In terms of heat conduction, the anodizing layer is practically negligible given that if you DON'T anodize it chemically, it will rust once exposed to air anyways. So might as well reap the benefits of a proper anodization. I wrote a paper on this way back in university.
+Skiddins It will still have the disadvantage of heat absorption heating the intake air. Though it is much better than paint.
Kevin Wong it’s just dye “soaked” into the aluminum oxide layer. Not sure if there’s any chemical reaction. I wouldn’t expect very many organic dye’s to react with aluminum oxide (somehow) and remain colored. Though there may be something out there.
So an automotive radiator isn't actually a radiator? More like a convection....ator?
Correct, and really convection in this sense is simply conduction with the air moving.
EE - Going to mess with some of my mechanic friends. lol
Check your personal Facebook (other messages) sent you a message about Engineering degrees etc. My initials are DH just in case you have quite a few messages.. Thank you. Awesome videos.
very informative info the one thing that i love in automotive engineering is usually the name of a part dictates it purpose/function amazing that it should actually be called a convection/er?
sounds more appropriate
@@aussieguy1012 except for backlight being the descriptive term for rear window ...
You always do a great job man.
Great video! Keep up the good work.
would i be correct in saying if the intercooler had a large surface area is more efficient than a smaller one thats thicker even if the air volume is the same in both. But then you also have to do a air flow test to see which flows for example 100 cubic feet of airquicker at the same pressure. Then way up pro's and con's to find a winner.
+Craig Sawyer
TL:DR Not necessarily
You may or may not be correct. An intercooler with a larger effective surface area would of course remove more heat from your intake charge, but the smaller, thicker intercooler may actually be the one with the higher effective surface area. The parts of the intercooler that actually release the heat are the little vanes in between the cores. The surface area of those vanes plays a very large part in the efficiency of the intercooler, and making the intercooler thicker is a very easy way to add a large amount of area to those vanes. I'm not going to claim to be an expert, or be able to walk you through the math behind it, but a smaller intercooler could outperform a larger intercooler if the difference in thickness was enough to make up for the smaller intercooler's lack of length/width.
The best way to find out for certain is to test both intercoolers under the same conditions and find out which one registers the highest temperature differential.
The air flow test wouldn't help you determine intercooler efficiency, since it has nothing to do with the cooling capabilities of the intercooler. It would, however, allow you to determine which intercooler was least likely to be a bottleneck in your induction system, making it a useful test to perform if the ultimate goal is more horsepower.
Thanks for getting back to me
Here's a better reply.
Lets say we have two intercoolers with identical structure in terms of tube design and fins per inch. And for arguments sake, both have identical internal flow characteristics and pressure drop.
Both have equal width (lets say 50cm), but intercooler 'A' is 20cm tall and 5cm deep, while 'B' is 10cm tall and 10cm deep.
Therefore both have equal volumes at 5000cm^3.
But intercooler A has a frontal area of 1000cm^2
vs the frontal area of B which is 500cm^2
Now, at times of low air speed traveling through the intercooler to cool it down, intercooler A should be more effective. This is because as an intercooler gets thicker it restricts airflow more and with airflow being key when it comes to convection cooling this is what will make the main difference. The air will have an easier time traveling through intercooler A therefore will be traveling faster though it and providing a greater cooling effect. I would think for this example A would always outperform B but the difference would got smaller and smaller as the speeds increases.
A secondary thing that could affect the cooling is the fact that as the ambient air travels through the intercooler it heats up. Intercooler A has a larger surface area to receive fresh ambient and should maintain a high temperature differential between the core and the ambient air (better for cooling). Whereas as the ambient air travels through the thicker intercooler (B) it heats up more before passing all the way through so there will be a lower temperature differential between the now warmed up ambient air and the rear part of the intercooler (not as effective for cooling).
Thicker intercoolers have their place because it all comes down to packaging. It's not always possible to have a large surface area thin intercoolers due to space and design constraints. Some aftermarket companies make intercoolers with larger surface areas for a platform where it's not suitable but end up having half of the intercooler hidden behind an obstruction like a crash bar for example. I find this frustrating as I can't see it helping the cooling much at all, while just adding unnecessary charge volume and overall weight. So a smaller thicker intercooler that makes the most of the available airflow would be better in that scenario.
TLDR; when buying an intercooler look for one that has the highest frontal surface area that has access to free flowing air. Only go for a thicker intercooler when the ones that have the higher frontal surface area have obstructions and don't receive a higher area of airflow.
P.S. This is all under the assumption of equal internal flow and pressure loss. I have seen a dyno graph of one intercooler that cooled the charge air 10 degrees celsius more than another but actually made 10bhp LESS. This is because even though it cooled better there was more pressure loss due to a restrictive core design.
r32 gtr, r32 gts, all gc8 wrx's and more all have oem black IC's. Its mainly to be less noticeable.
Dude, that was fantastic!!!! Love it!!!!
Mighty car mods may have considered how the essential role of convection in an intercooler but were just trying to start a trend with modified car owners like themselves and that was their message at the end of their video as the difference between stock and painted was insignificant (to them at least). Both Engineering Explained and MCM videos are amazing keep it up guys!
It's a hot sunny night in here... :D 3:28 :D
That made me laugh. I wonder if he meant to say it on purpose, or if it was just a slip of the tongue.
doing the same. Check. Carry on.
...Happens in Pokemon
3:32
2 vids in... subscribe you make my brain tingle.
Thanks for subscribing! Hope you enjoy the tingle.
Hi EE. I had the privilige to attend a heat transfer class taught by Yunus Çengel in his home country at Ege University where I got my Bioengineering degree and PhD. He is a great teacher. It's also cool that we have something in common. Keep up the good work!
PS. even though I don't own a car I enjoy watching your videos an feel like I won't be doing all those worng stuff once I have my car.
Great explanation. Very clear and complete. The part with the chimp was definitely convincing that 3% could be a big difference. Well done.
Just wanted to point out that the mighty car mods test showed that the black radiator radiates heat better with no airflow but performs worse with airflow
Because of the insulation, yes. More air flow means more work to cool it that doesnt work..maybe a water pump spray that is temp regulated?
+ThoughtElevator: LOL
"Hot sunny night"
Not one of my brightest moments. Oh bad puns...
Hey could be that way in Alaska
well if it in Siberia :)
Hi.I love your videos!very informative,literal and on point.I’m not really that into cars anymore.but the one question i never found an answer to when i was still very interested is how to choose the correct size intercooler for a 2ltr lancia delta integrale engine aiming for around 550 bhp?Car is a time attack race car on tarmac.
Wonderful info!!!!! Would having something that doesn’t rely on airflow to stay cool be better in black? Something like radiator overflow, aftermarket power steering fluid reservoir, oil catch can? Would these dissipate heat faster under hood being black, or still soak up more heat coming off other things in the engine compartment?
That MCM video also made me cringe a bit. What they seemed to fail to realize is that an intercooler is mainly used to cool air that was heated by using forced induction (turbo, supercharger). When your car is standing still, you have no boost, and no need of it, so there is also no super hot air to cool.
Yes indeed! Great point to add.
Another mechanical engineer here, here's my two cents. Painting an intercooler in the hope of performance gains is misguided, and that's well explained in the video. One thing that wasn't totally covered is just how insignificant radiation is in a system like this (VERY). But it's a good video. However a lot of people are looking for the aesthetic effect, since an unpainted aluminium fmic is not to everyone's taste. If you paint the front surface only, so that only the leading edges of the fins are painted, you will get virtually the same aesthetic effect and it will have minimal effect on heat transfer, since most of the surface area of the fins will remain unmodified (all the heat transfer work is done on the surfaces parallel with the airflow, the parts of the fins you can't really see, which have enormous surface area). You would be painting a fraction of a percent of the surface area. Obviously it would have to be done by hand as opposed to spraying. Personally I would leave the intercooler alone and go with a dark grille in the bumper in front of it. It will tone down the look of the car and protect the fragile fins from being damaged by road debris. Over time you get enough dents and that will drop the efficiency of the heat exchanger substantially, as the airflow between the fins gets blocked/disrupted. So add a grille, it's functional and you can adjust aesthetics with it without goofing around with important engine parts.
+Faketrollname sevenbillion Kind of a random question here from an engineering student, but one thing I've always wondered is why they don't use the hood for cooling? Construct it from aluminum and put fins on it like a heatsink. Wouldn't that eliminate the need for airflow through the engine bay, and reduce some drag?
decidiousrex Because you couldn't transfer enough heat fast enough from the block, through the air, into the hood. If you decided to use a coolant fluid to get the heat up there, it would be more complication than it was worth, as the system would need to detach when the hood was opened, and finding a location for the expansion tank would be hard. If you did figure out some way to get the heat up into the hood that was simpler than a normal system, you would then have to figure out what to do when the car was static (natural convection isn't enough), which would mean a fan drawing air over the hood, and I'm not sure how you'd package that. The fins on the hood would make engineering for pedestrian safety more complicated. I'm not saying it's impossible, but those are a few drawbacks I can think of.
Faketrollname sevenbillion Definitely some obstacles I didn't think of. That's more of an idea I thought of while in the shower than a seriously thought out plan. I'm sure if the saving in drag (if there is any) outweighed the added complication, automakers would be using that system.
I'd rather see thermoelectric power generation used to cool cars, unfortunately the tech simply isn't there right now. Maybe someday....
+decidiousrex I had a coleg how said that there are sport motorcycles that use the body of the bike as a radiator with integrated pipes but is very expensive to repair if damaged. I am not sure if is true, not sure if I remember corectly.
+Adrian Draganescu , this is true of the Harley V-ROD. Only that the oil from the engine and water is going through part of the cycle FRAME like a water jacket. I added an optional oil cooler ( like a black small intercooler ) to dissipate heat while on the road between Houston , Tx and Arizona. It helps drop the temp in the engine by at least 10 degrees. It comes anodized black just to match the bike. JK.
Great explanation of thermodynamics. Every word make sens to me.
Great video. Can you explain why the temperature difference was so much in favor of the black intercooler without the fan? I know there will be no forced convection in this case so the intercooler will be much less efficient, but what makes the outlet temperature so much lower on the blak intercooler? Is it increased heat transfer by radiation?
ok, what if the intercooler is anodized in black? It´s not black paint, it´s the alluminium itself turned in black. will it affect the convection tranfer of heat?
Yes. Anodizing is an insulating layer but far thinner than any paint.
Anodizing a colour into something still involves another component, it's not paint exactly, it's more of a dye. The anodizing process purely by itself simply increases the thickness of the oxide layer on the surface of the part. The thicker oxide layer is then capable of "absorbing" the dye.
But yeah, good question, I'd like to know the answer too. :)
"Anodizing (also spelled anodising, particularly in the UK, India and Australia) is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts."
Its adding / thickening the layer on top of the metal, not changing the metal itself. Think of it as very thin paint put on with electricity.
But it would still be black instead of reflective. So it would absorb more heat. Everyone knows that the inside temperatures of black cars get higher when left in the sun then the inside temperature of white cars. That's just basic science dude. It may not make much difference. But there is no way in hell it would improve the heat transfer..... (which is the whole point to the theory....)
No motor sport of any type does this.
Waiting on the MCM response.
You can't argue with thermodynamics. Well, not unless you have a carefully worked out experiment that shows some element of it to be wrong with a high signal to noise ratio and the approval of a peer review body. #science
Dude I love you so much. I feel like if we went out for a beer, we could talk for ages without it getting boring.
That's creepy.
Kalel Kent not really. Just a dedicated fan
3:31 "If it's a hot sunny night... I don't know why you'd have a campfire" HAHAHA! Good one ;)
People have been painting intercoolers, black for decades, but not for higher performance, but for stealth. Some people like the idea of a wolf in sheeps clothing, and some just don't want the attention that front mounted intercoolers bring, such as from cops, or having every little dipshit rev at you in their shit box.
"Hot, sunny night."
I love sciencey people :)
I'd like to see you do another short video about this topic and include the difference in air density so we can see how much more volume in terms of air the non-painted intercooler provides.
I love your videos and as well M C M videos and I'd love to see you all 3 doing some mods ; Cheers !!
Hell no, I'll paint it pink if I want to lol
3% of a larger number may have been significant, but with the MCM example of 97-degrees (C) versus 100-degrees (C) IS negligible.
THAT 3% difference equates to only about 5-degrees (F) under air-flow (convection) conditions.
The 39-degree (C) improvement under heatsoak conditions to ME is a stronger argument, and to me provides a much greater advantage over a 5-degree (F) loss.
That's about a 70-degrees (F) improvement, btw.
Also, I do believe BMW paints their factory intercoolers black.
You don't need to reduce the intake charge temp if you're not moving. You're also not creating boost if you're not moving, and thus not compressing the air (and increasing it's temp).
Couldn't the paint simply be a fashion statement? And/Or to keep the aluminum from oxidizing maybe even increasing the thermal conductivity? I'd have look at aluminum oxide conductivity... but it's hard so I'm guessing it's not very conductive. Just some thoughts.
Engineering Explained you should really do a video on the thermal effects of heatsoak after sitting at the lights or a drag strip... than youll have a real conclusion... the debate is still half open, more types of driving suffer from heat soak conditions compared to continual air flow... unless ur straight out track racing or fwy cruising how long do u actually sustain a high psi period for?? 400m at a strip... and how ever far you can on the street, then back to heatsoaking again... each situation is individual but im with mcm on this as heatsoak occurs alot more then airflow, mind you im not going out painting my ic anytime soon... if its that big of a deal to any one, you would jus go water injection...
When you talk about these kind of numbers on this kind of setup you shouldn't expect linearity on the differences between them; when conditions get harshest, f.e. going high speed up a mountain on warm weather, the painted intercooler will reach its empirical heat-dissipation ceiling much faster, over which things will start to look nasty for the rest of the engine.
The reasons behind this are not only related with the temperature gradient formed on the paint layer, but the change in material rugosity due to the paint layer would be quite relevant at high air speeds, both of which affect the convection process. Also this limit is not a hard-knee bent, and you would start to see it's effect much earlier, where the gap would widen in bigger and bigger percentages as more heat dissipation is demanded.
About the no-airflow part of the experiment, I would like to know how the thermocouples where placed on the painted intercooler, cause in such a experiment, with natural convection in play, the aluminum thermal conduction plays the biggest role, and if they just placed the thermocouple on top of the paint then you may just be quantifying the thermal insulating properties of that particular layer of paint. If it was indeed well positioned, I would still look at natural convection and conduction mishaps, as radiation should ammount to the smallest heat dissipation of the three available.
Really nice videos from both MCM and EE, mythbusting is always an involved task, but a necessary and rewarding one at the same time.
Intanius You can use Celsius for a delta T (T°-T°), it doesn't make a difference on the result.
Only reason I can think of for putting a coating on an inter cooler is to protect it from the elements/rust. I work in appliance repair and some manufacturers had to put a coating on the evaporator because they started putting them in the fresh food section and they were constantly wet and got little tiny holes in them.
Absolutely smashed it right there! Victory to you!