Question on Coating outside of intake and heat related questions

[Redfox0099]

Disclaimer: I am not an engineer or have a science degree, if I did I probably wouldn't be asking these questions

1. If you coat a rough surface it will reflect better...correct?

I was outside with my IR thermometer just messing around and put it on my wall and then the mirror next to it....the wall showed more heat in the sun than the mirror but the mirror felt hotter...so if you coat something rough like the 6.1L intake and make it smoother won't it automatically show less a temperature cause it is smoother and reflects differently???

(not sure on the physics of this but I had to ask)

2. If you coat the outside of something metal with a heat barrier won't it make the outside cooler by not letting heat out to the outside....therefore keeping the heat inside and making the inside HOTTER?

I did an experiment in High School for NEDC (National Engineering Design Challenge) where we were trying to make something metal that was hot cool to the touch....cooking ware if I remember to keep people from burning their hands or something. We coated the outside of a piece of metal with some gel coating which made it cool to the touch...but the other side got hotter.....

If we coat the outside out our intake with something won't it make it cooler to the touch but make the inside where the air is hotter?


What if we coated the inside?
I know this is a lot but I have a lot of free time now cause of my knee surgery and have been thinking this over....now please come in to this thread and shoot my ideas down

[WickedSRT8]

A long time ago, several people had thier CAI tubes Jet Hot coated and claimed that it helped a bit with the intitial intake charge (which is what a CAI is really good for)... some actually got heat sheilding / insulation and wrapped around the box where the filter was, and around the tubes. Again, they claimed improvements, but I never really saw any facts following that up.

It would be great to get a logger of some sort and monitor the AIT sensor (I assume the car has one) to see just how well the CAI works on its own, then wrap it in insulation and check the values again. I did a similar experience a very long time ago (wont' bore with the details), but it seems that most "box" style CAI would be good for about 20 degree difference in initial intake charge... would like to do this again, if I could find a good logger! Any suggestions?

[Redfox0099]

I am not talking about the cold air intake......


I am talking about the intake on top of the motor..the big silver thing people are having coated....not the cold air intake tube or anything else...the big intake that sits on top of the motor

[lafrad]

well, if the heat source for the metal is the metal itself.

Stock SRT setup: heat is transferred from the heads, through the intake manifold gasket, into the metal intake, ANY insulation on the Intake manifold will *keep the heat in*. The engine is by FAR hotter than the air in the engine bay. The only source of *hotter air* is the exhaust manifolds... and their method of transferring heat to the intake manifold is not nearly as efficient as the physical connection of the intake manifold to the heads.

Only when you get insulation between the Heads and the intake manifold does a coating *really shine*. As soon as the intake manifold is able to fall below the temperature of the heads, then the air/heat convection/conduction starts to warm the intake manifold. Coating the outside prevents a warm(er) engine bay from transferring heat into the manifold.

The *real* benefit would be to coat the INSIDE of the manifold with a heat-transfer-resistant compound. Then, the metal itself could be any temperature it wants to be, but heat transfer from the metal to the air would be minimized.

[LouZ]

I am not talking about the cold air intake......


I am talking about the intake on top of the motor..the big silver thing people are having coated....not the cold air intake tube or anything else...the big intake that sits on top of the motor

I started a thread "IAT observations" IMO the heat source is the engine bay. Even driving around at 65 MPH the IAT is 5-6 deg higher than the AAT. In the staging lanes (this weekend) that rose to 20-25 deg with the fans on. After the run it was still +10. I plan on coating the CAI tube as well as the manifold(with a thermal barrier between the block and manifold). Since the air is moving and heat is not being absorbed thru the tube or manifold....it should be cooler.

[MomsR/T]

1. If you coat a rough surface it will reflect better...correct?

reflect what? a tree is rough and doesn't reflect.........stripping it doesn't make it reflect any better.

Will a pane mirror reflect better than a broken mirror?

I was outside with my IR thermometer just messing around and put it on my wall and then the mirror next to it....the wall showed more heat in the sun than the mirror but the mirror felt hotter...so if you coat something rough like the 6.1L intake and make it smoother won't it automatically show less a temperature cause it is smoother and reflects differently???

thats because your IR is measurring the heat OMITTING from the surface and not what the temp actually is............the lazer is measuring the deflection of the IR beam in the air surrounding the surface.

We use this in natural gas detection.........

2. If you coat the outside of something metal with a heat barrier won't it make the outside cooler by not letting heat out to the outside....therefore keeping the heat inside and making the inside HOTTER?

But won't flowing 700+ cfm constantly cool the inside?

I did an experiment in High School for NEDC (National Engineering Design Challenge) where we were trying to make something metal that was hot cool to the touch....cooking ware if I remember to keep people from burning their hands or something. We coated the outside of a piece of metal with some gel coating which made it cool to the touch...but the other side got hotter.....

Wonderful..............thats why we tell people to use the PPP insulated gaskets............did you put your cook ware on oven-mitts?

If we coat the outside out our intake with something won't it make it cooler to the touch but make the inside where the air is hotter?

Not if you isolate it and run air thru it............


What if we coated the inside?

We'll do whatever you want...............not sure why you brought it up for discussion here.................

I know this is a lot but I have a lot of free time now cause of my knee surgery and have been thinking this over....now please come in to this thread and shoot my ideas down

There are 2 issues...............heat giving and heat obsorbing...........heads give off heat, but the heat will go to path of least resistance..........air.

We isolate the intake from the head...........then we try to keep the underhood temps from effecting the intake...........

Lastly, our design has proven to work best when the car is in motion...............but can heat up as normal if it just sits there for a long period of time..............at the track is where its done well with running back to back like we did in E-Town.

[06SilverSteel]

Lee, correct me if I am wrong, but is the poly dyne stuff a ceramic type of coating??

[MomsR/T]

yes

[06SilverSteel]

Thought so..........

you know the cool thing about ceramic is....you can put a torch on it and touch it with a bare hand just a few inches away.....awesome heat dissipation.

[MomsR/T]

we don't coat the interior for 2 reasons:

1. thickness of runner interior once coated

2. inability to cool by flowing air...........we rather use the exterior coating to keep out hot environment and use the fast moving mass of air to cool the interior w/ heat resistant gaskets.

COating both sides may HOLD heat thru gaskets..........weakest link

[BAKBRNR]

A mirror or shiny surface will reflect heat, that is why they mirror the inside of a thermos bottle. This would help keep the other side cool if the heat source was from the air. In this case however the heat is transfered through the metal from the engine and I think there would be little advantage if any, in fact may actually have a reverse effect, not allowing the air flow to cool it as much. Just my two cents.

[392Stu]

This sounds like a conversation I had with Red and then discussed with Steve yesterday about us performing some testing and trying out some ideas in the future, possibly on Reds intake. Heres my take for what it's worth. This is just an explination of some Physics as I see it in this application. I appoligize for the grammer and spelling, I'm an engineer and not an english teacher.

IR thermometers measure by IR (radiation) a major component of this measurment is the ability of a surface to emmit and except radiation. This property is refered to as emissivity. This is a value between 0 and 1. A microscopicly rough surface that emmits perfectly is refered to as a black body radiator (no relation to color at IR wavelengths, it's surface finish though) and has a value of 1. A perfect radiation reflecting survace has a value of 0. Emmisivity can vary with the frequency of the radiation being discussed.

Your typical budget IR thermometer comes with the emissivity set at a predetermined value of around 0.95 which represents most surfaces unless they are smooth. Since this is an important paramater in taking IR temp readings it would need to be accounted for and I suspect there is a big difference between a stock intake surface and a coated one.

The Emissivity also directly effects the ability to transfer heat through radiation which I suspect when there is relatively low air flow past the intake like when in the staging lanes is possibly half the heat that is dumped by the intake to the exterior of the engine. So having a different emissivity on the intake will definately effect the IR thermometer readings to make the smoother surface look significantly cooler and it will also effect the ability of the surface to transfer heat through radiation.

That being said. The intake manifold will heat up due to conduction (the most efficient form of heat transfer, convection from air is one of the least efficient) from the heads at the gasket surface and from convection from the heads and block. So a barrier between the manifold and head and manifod base and block would make sense because it would impair heat transfer to the intake and therefore yeild a cooler intake.

On a stock intake I see two areas that the intake is cooling from and two different cooling methouds. Since the intake is not in physical contact with anything of significant mass that has a lower temp conduction (just the CAI) is not a mechanism for cooling the intake. As discussed, radiation from the outside of the intake into the engine compartment is going to be a factor particluarly when air flow is minimal in the engine compartment. I'm guessing from previous experience on stuff I design in my day job, that it could be as much as 50% in low airflow conditions thus you want a high external emissivity on the outside of the intake. The rest of the cooling is done by convection. Since velocity of air is directly porportional to the effectivness of convection in all likleyhood the most cooling is evident on the inside of the intake where the air velocit thru the plenum and runners is high. Any cooling from this will heat the air going into the combustion chamber and result in a loss of power regardless of manifold temp because the manifold is cooled at the expense of heating the air charge which is the real effect we are trying to aviod. Therefore I would recommend a thermal barrier coat on the inside of the intake, although the manifold will almost certainly measure hotter.

Next to facilitate convective heat transfer from the outside of the intake I would leave it alone. A barrier coat in my opinion would impead convection to the cooler engine compartment air which and make the intake hotter. The rough cast surface is also a bonus for radiation.

That my opinion.

[Beast 2]

I'm going to stay our of this one for the most part... seems to be a touchy subject.

I think you guys just need to run my custom intake/air cooling device.

[Redfox0099]

Wow my head hurts, thanks Stu....how about we put a tempature gauge on the inside of the intake and take measurments.... sounds like a good experiment to me

[392Stu]

Yeh, drop a thermocouple into the intake port just north of the head. That would be an excellent test.