Is there any evidence that painted EFI intake tubes will make the engine run hotter/cooler depending on the color?
Over at 914 groups someone posted that when he painted his intake tubes black the engine ran 20* hotter.
So if you paint the tubes a light color (reflective, not absorbing heat?) it will run the same or, cooler?
I have seen nicely detailed engine bays where the plenum and intake was painted the body color. Could this be a functiional mistake?

DUH! yellow is faster!

i doubt it would make any measurable difference.

Does'nt make sense to me. How could black affect the engine temp... there's no light in there? Color affects temp on a visual basis, not a mechanical one. Put a black 914 & a white 914 in the sun the black one will get hotter. Put them in the shade & the temp stays the same. Perhaps it was the content /makeup of the black spray paint he used? No insulation value from the engine heat?

From the factory they are painted. Maybe someone ceramic coated them. Oh but that would keep heat out, as the runners are bolted to the heads with a plastic block insulating between it and the head. Horsecrap, oh wait maybe he forgot those phenolic blocks/spacers when he reinstalled.

the person who stated that needs to put down the crack pipe and step away from the keyboard.

I noticed my car ran cooler when I replaced the muffler bearing

yes. flat black is the worst as it absorbs heat much better than, let's say a bright and shiny white ...

flat black runners will get warmer by absorbing more heat from the engine compartement ...
Andy

nice try, but no dice ...

heat *is* light. just because YOU can't see it doesn't mean it isn't there. your (mine, humans in general) range of vision is very limited. there's much more light than what *we* can see.

flat black does not care about what you or i can see. it'll absorb surrounding heat much better than a lighter color ...
Andy

Good response, interesting point.

Andy is right.

In theory, the black runners will absorb more heat. But in practice, you will not see a measurable difference in engine or intake air temperature based on the color of the intake runners.

If i put two parts in an oven, one white and one black, and turned the oven to 140* (engine bay temps)you are telling me the black part would be hotter!?

Keith

heat is radiation.

I believe they were painted a lighter color intentionally, and should not be painted black, but light grey or even white.

they reside over the black cooling tins which give off a large amount of radiant heat.

flat black has a 1:1 absorptance/emmittance ratio meaing it absobs as much as it gives off.

white on the other hand is 1:4 ratio meaning it gives off 4 time more than it absorbs which translates into a REAL WORLD decrease in its working temp.

Its known as "temperature of equillibrium"
this is measureable stuff not theory.

the black part will reach temp faster.

equillibrium has alot to do with exposure.

simple physics ...

interesting, good thing I am gong with chrome P coat on my intake runners. Not only will they run cooler ,my car will go faster

Once again, yes the black runners will absorb more heat.

But the question was, does the paint color make a real difference to engine or intake air temperatures. To answer this, the question becomes, how much more heat will the black runners absorb?

Within the engine bay, and given the area of each runner, I would estimate that we are talking about less than 2 watts of power (per runner) difference between black and white runners (really I think it's less than 1 watt).

Anyway, the runners have relatively cool air running inside them. A 2L engine at 3000 rpm pulls around 50 CFM of air through each runner. With this volume of air, it will take ~16 watts of power to heat that air by 1 degree C.

So you can see that at 2 watts, or even 5 or 10 watts difference, you would only be heating the intake air by a fraction of a degree.

Hence, paint your intake runners any color you want.

the radiant source is the engine tin which is signficantly hotter than the engine bay temp especially sitting in traffic.

sitting at idle in traffic I would wager your pipes would get rather hot, so why speed up the process ?

just my opinion, feel free to blow up your motor with the wrong color paint.

blow up your motor with the wrong color paint!!!

Wow. This thead has taken an interesting turn.

The factory decided to put the stock 2L engine air intake in a location where it draws in air that is more than 50 degrees F hotter than the outside air.

Yet, apparantly, they also painted the intake runners a light color to prevent further heating this air by a fraction of a degree. And this fraction of a degree will blow up your motor if you paint your intake runners with the wrong color!

the question was, would you see hotter head temps with intake runners any other color than stock grey. I think the answer is NO!

blow up your motor with the wrong color..... classic!!!

thats called sarcasm.

I know, it was great!!!!

phew, recovered on that one.

i wonder if they were trying to match the intake air temperature to the fuel temperature at the injectors.
for perfect mixture and efficiency, you know ...

after all, the fuel rubber lines are black and the fuel tank is painted black as well! (and that's a HUGE surface area)
Andy

Heat is not light. Light can emit/project heat but where is the light in lets say a chemical hand warmer? Heat, the kind we're talking about- not radiated energy but absorbed, is the excitement of molecules in an object & there are other forms of energy that can excite molecules into a heated frenzy besides light; electricity for one. What color something is only relates to heat within the light spectrum- pour gas all over a white teener & a black teener & I don't think the color will really matter. Put 2 teeners in the sun & the black one will be hotter than the white one, period. We can't see infrared or ultraviolet but how those particles impact onto a surface is still going to be measured within & outside of the visual light spectrum. Cut the light out & that range of heat is removed. As to weather or not flat black absorbs more non-visual heat over white is what did not make sense to me. Poor choice of words on my part before.

Ok, how about stripping the paint off down to bare metal, wet sand, buff a bit, then shoot the tubes with clear coat? Get a"natural" industrial look on top of the motor, and efficient temp wise(?)...

This sounds like a mythbusters moment, whos going to volunteer their cars?

- they'd both be @ 140* black or white

The runners are very short and the air RUSHING through them is rather quick so the short answer is "No, runner color doesn't make a difference". If the air had time to 'puddle' in the intake runner one may have a possible arguement.

That's asking for some serious trouble!! NOT!

do what you like, it won't affect a thing. there are ton's of things to worry about that will affect engine temps than the color of the intake runners

If you think about it, in modern cars almost every intake manifold is flat black plastic. I doubt every auto maker in the world is that clueless...

sure it is ...
photons waving through space, occasionally pretending to be particles.
only difference from visible light is the wavelength, amplitude and energy content ...
(note that talking about visible light implies that there also is non-visible light, otherwise that distinction would be useless)

you might want to freshen up on your quantum mechanics basics ...
Andy

Excellent point, they are & they're all under the hood absorbing heat from the engine & not from a light source.

Heat can emit light & light can emit heat but they're called heat & light because they're measuring 2 different things.

but thats plastic dude.
totally different head.

like i said, you might want to walk down to the library and pick up a book on quantum mechanics ...

heat and light are called different things because when man gave them those names they knew nothing about photons or subatomic particles.

the words "light" and "heat" have been around for a long time.
that does not mean anything, as both are man-made distinctions of the same thing, and not a fundamental difference in nature.
Andy

again, heat and light are just two different words for the same thing.

electromagnetic radiation

same thing, just different wavelength, frequency, amplitude and thus energy content.
Andy

OH boy!, look what you started

Keith

Einstein, paging Dr Einstein...

Those darn teachers said math would save my life someday, should have paid more attention in physics.

& somehow I agree w/ a good part of what you've said. They are man made distinctions of natural energy waves- what we can feel & what we can see. Technicaly if you remove the light spectrum from the equation I would suppose that the flat black finish will still absorb non light particles over the white surface @ a faster rate. But the black pot in the oven actually gets hotter than the white pot? I can buy it will get hot faster but how can it get hotter?
Oh yeah, why don't you mail me a book instead ? My legs hurt & I'm tired of walking right now .

try this one:

The Elegant Universe, by Brian Greene

it has a really good section on electromagnetic waves and how maxwell and einstein and planck eventually figured it all out and established todays quantum mechanics ...

it's all just electromagnetic waves ...
Andy

Yeah, but if we are talking color, wouldn't they make them out of light gray or white plastic?

I believe the distinction you are looking for is the difference between a photon and a phonon
The phonon is the vibration of a lattice (such as that present in any solid) and is "heat" in that it is representative of the kinetic energy in the material. The interactions with photons can produce more vibrations in the material (and thereby make it hotter)
The heat that you are talking about, though, is the heat being emitted from other parts of the engine bay. That absorbed heat is largely IR radiation.
And Andy, definitely a good book


[/nerd]

Quite frankly I'd paint them pink at this point just to change the subject .

I thnk pink would drop the temp by 20 degrees...

There are many ways to add heat to an object. But for this discussion, lets just consider two: conduction and radiation.

In your oven (or your engine bay), both of these occur. Conduction is when the heating element heats the surrounding air. When the air gets hot, it passes some of it's heat to the object in the oven. Considering only conduction, the color of an object won't really matter. The object will only reach (or come close) to the temperature of the surrounding air. This is how most people think of an oven.

But there is also heat transfer occurring by radiation. Heat is radiated directly from the heating coils to any place in the oven that might absorb it. A black object will absorb this much better than a white object. So the black object will heat up faster, and can actually obtain a higher temperature than the surrounding air.

Does this make sense?

Just go outside and you will realize it for yourself. Go stand in the sun. Your skin temperature will quickly rise higher than the temperature of the outside air. This is because radiated heat from the sun is being absorbed by your skin. And this isn't all because of visible light. Remove visible light from the equation and you still have lots of other frequencies including infrared - which we all know works very well for transferring heat via radiation.

In reality, I don't think that conventional ovens do much heat transfer by radiation - but it is there. In contrast, a toaster oven does a large percentage of it's work by radiation. That's why you can cook a turkey pot pie in a toaster oven in under 10 minutes, but it still takes 20 minutes in a preheated oven.

pink is definitely hot.

I thought this was my point? Color is relative to radiation, not conduction. However as Andy has so eloquently pointed out these are man made distinctions of electromagnetic energy. Take radiation out of the equation & the black pot still heats up faster than the white pot, cools down slower. But I still don't see it getting hotter. The oven is set @140*. It will take the white pot longer to get to 140* but when it gets there the black pot will still be at 140*... no?





BTW- there goes my idea for a pink intake .