Warm air intake by painting your intake manifold black

[Matt Timion]

SVOBoy and I were chatting about this tonight.

The idea is that by painting your intake manifold black you will increase the temperature of the air being sent into the engine. This is based on (I assume) the fact that black attracts heat.

I personally don't think there is any validity to this type of thing for a number of reasons.

Instead of being a negative off the bat I figure I'd open the floor to others.

Yes/no? Pros/cons?

[diamondlarry]

SVOBoy and I were chatting about this tonight.
The idea is that by painting your intake manifold black you will increase the temperature of the air being sent into the engine. This is based on (I assume) the fact that black attracts heat.
I personally don't think there is any validity to this type of thing for a number of reasons.
Instead of being a negative off the bat I figure I'd open the floor to others.
Yes/no? Pros/cons?

I would think that there wouldn't be much benefit. It seems like this would only work for capturing heat from the sun. If anything, in an engine bay that's basically isolated from the sunlight, if painted, the paint may possibly provide a layer of insulation from the engine heat. Thoughts? Comments?

[GasSavers_DaX]

In heat transfer, we learned about 'black body radiation.' The only way something painted black will absorb more heat is through radiation [not convection or conduction]. In all actuality, a 'black body' doesn't even have to be black...it doesn't even really exist. It is a theoretical body that has an absorptivity value of 1 [conversely, an emissivity value of zero]. Unless you have something under your hood that is emitting radiation energy, or unless you drive around in the daytime with no hood, I personally don't think you will see any benefits.

Sorry to jump to the negative side.

[SVOboy]

Me: Say something about why black will make the IM hotter.

DrDisco: because it absorbs radiated heat, while shiny **** will reflect it

Me: And what about black and light, does it still make sense?

DrDisco: light?

Me: Light being absorbed by black, but no light under the hood...

DrDisco: light is one kind of radiation

DrDisco: heat is another

DrDisco: heat does not require light to radiate

Me: Thank you, sir.

DrDisco: energy is interesting

Me: Guy I'm trying to convince won't buy it.

DrDisco: that what, heat is radiation?

Me: That it'll get hotter without light.

DrDisco: how does a microwave work

DrDisco: hint: the little light doesn't heat the food...

DrDisco: like an oven

DrDisco: radiant heat

DrDisco: not light

DrDisco: the microwave uses high-frequency radiation

DrDisco: light is a narrow part of the electro-magnetic spectrum

DrDisco: you've seen Predator?

Me: No.

DrDisco: oh

DrDisco: that's sad

DrDisco: anyway, you've seen infrared pictures, right?

DrDisco: pictures of heat, instead of light

Me: Yes yes.

DrDisco: and they can be taken in complete darkness, like the military stuff

DrDisco: so heat does not require light

Me: Why would a black IM increase the heat?
tallguy pw0: well does a black car get hotter then a white car
tallguy pw0: in the heat
Me: But there is no light under the hood.
tallguy pw0: do a test paint a spoon black and paint one white, put them in the oven and see wich one gets hotter. if you have a infrared thermometer
Me: Hmm.
tallguy pw0: search ht there was a thread about it

I still need to search h-t about it.

[Matt Timion]

Originally Posted by DaX

In heat transfer, we learned about 'black body radiation.' The only way something painted black will absorb more heat is through radiation [not convection or conduction]. In all actuality, a 'black body' doesn't even have to be black...it doesn't even really exist. It is a theoretical body that has an absorptivity value of 1 [conversely, an emissivity value of zero]. Unless you have something under your hood that is emitting radiation energy, or unless you drive around in the daytime with no hood, I personally don't think you will see any benefits.

Sorry to jump to the negative side.

Quick question... Is the engine itself emitting radiant heat?

[Sludgy]

Ah, this takes me back to the good old days of carburetors. Back then, most cars had a tube that snaked its way from a shroud around the exhaust manifold to the carburetor. This was because when air accelerates through a venturi, it gets cold. The cold air would then condense water from the air and ice up the carb throat. The automakers added the warm air tube to prevent icing.

I had several unpleasant experiences with carburetor icing. When I was driving my ex-wife to the hospital, the carb in my Ford Maverick iced up, and I had to pull over. A State Trooper stopped and took her to the hospital. After the car sat a while, the ice melted, I was able to restart, and I finally made it the last few miles to the hospital to see my son born.

I also drove from Burlinton, VT across Canada to Sault Sainte Marie, MI on a cold, clear winter night in a Fiat whose carb heater tube was missing. The Fiat had a 2 barrel carb, and when the primary iced up, I just tromped on the gas to open the second barrel. This kept me going, but carb secondaries always run rich, and the gas mileage sucked. I was running out of gas, so I stopped at a closed gas station. I left the engine idling for heat. When it finally ran out of gas, I nearly froze my hiney off. In the morning I was able to get some gas. Damned carb iced up just about the whole trip, but after nearly freezing to death, I was a lot more careful about keeping the tank full.

So, if you really want to warm the intake air, install a shroud over the exhaust pipe and run a tube to the air cleaner. That'll be a lot more effective than black paint.

[GasSavers_DaX]

Originally Posted by Matt Timion

Quick question... Is the engine itself emitting radiant heat?

Yes it is. Someone should probably try this. I still think it isn't going to get that much hotter though.

[SVOboy]

The thing that got us started on this was the guy that painted his intake (whole thing though, not just the manifold) white and claimed a 10C reduction in IATs.

[Capcom]

Even there is no visible light in a "thermos" the innerside of it is silvered in order to reduce infrared radiation to go out ..So opposite must be somewhat true also: Black paint probably absorb more infrared radiation generated from engine even no single visible light ray exists under the hood.
But i also think that it will not make much difference.

[kickflipjr]

I don't think it will make a difference. If it will the change would be very small.