WANKfactor

iTrader: (1)

I still dont get it, youve got (hopefully) cool air running through the intakes, and (most likely)hot air outside of them, so while the engine is running, surely some form of insulation will keep the charge cooler.
Would putting thermal dispersant on your air conditioned house instead of insulation keep you cooler on the hottest day of summer?
Clearly I'm missing something here..

David Hayes

iTrader: (6)

^ ioTus has it in a nutshell. You are going to have heat transfer regardless and a barrier would just simply trap the heat in the intake (like it does on an exhaust), causing temps to be higher. A dispersant will take this heat out, lowering your AITs. I think the mistake you are making WANKfactor is to believe the barrier will keep the metal of the UIM from getting heat soaked. It will only delay this but the metal will get hot and then the heat will be trapped inside the intake, raising temps. It would be cooler to the touch though but what we care about here is the inside air temps.

I have also heard of what ioTus describes, coating the bottom with a barrier and then the top with a dispersant. In theory, the barrier on the bottom will help to keep out heat from the engine block and the dispersant will then transfer on out whatever gets in.

There are a bunch of details on both ceramic barriers and dispersants on the last few pages of my build thread as this came up there for quite a debate. I am not a ceramics engineer nor do I work for a coatings company, but my Borg Warner turbo sponsorship got me interested in the use of barriers and dispersants. Prior to this, I did not know there were different ceramic coatings. So, my turbo has a ceramic barrier applied to the AR to hold the heat in, my bearing section has a dispersant to remove heat from the bearings, and my compressor cover has a dispersant to cool the metal and reduce the intake charge temp.

Here are some details on the use of dispersants but go to my thread for more info:

"Heat travels to cooler areas, it will do this through the path of least resistance.

The thermal dispersant coatings are designed to provide the path of least resistance, the coating is designed to put the thermally conductive materials in close contact so that the heat moves quickly to the cooler areas.

The application process also enhances this path of least resistance because the surface is etched before application of the coating, this removes any oxide layer that may have been there (the oxide layer is a thermal barrier). The coating itself is corrosion resistant and so will prevent the oxide layer from forming again.

A thermal dispersant also has the affect of reducing hot spots. It does this by conducting the heat across the coated surface faster than the base metal can. If this coated surface is exposed to a cooler medium (air, water, oil, antifreeze, etc...) the heat will move to the other medium faster because it has more heated surface in contact with the cooler medium.

A 20 to 30% reduction in temps can be expected and is dependent on the application. Factors that will have an effect on the dispersing of the thermal energy include; temperature of the heated surface, temperature of the cooler medium, flow rate of the cooler medium, etc...

Regarding heat soak - If there is a place in the path of thermal conductivity that the cooler medium does not flow (example: air trapped in an insulated area), the heat has no where to move to and will build up until it is at the same temperature as the heated source. This is where one must look at the thermal path one is building and make sure that that path has no areas to allow heat soak. The coating will allow one to build that path of least resistance to the area that allows the flow of the cooler medium to carry away the heat."

So, yes Ohnono, call your guys if they haven't already done the work and have them use the right stuff. They can get the dispersant from Techline Coatings. It's called TLD.

WANKfactor

iTrader: (1)

Im just going off the assumption that the charge air inside the intake is cooler than the surrounding air in the engine bay, and therefore heat dispersant will be transferring heat IN to the intake pipes and manifold.

David Hayes

iTrader: (6)

I am only offering what has been explained by the experts and is available on just about every ceramic coatings website.

An FD intake manifold is metal and will pick up heat transfer from the engine. Start your car and watch AITs go up. You don't need to achieve full heat soak here like when you turn the engine off but you will see a rise in air temps. So, to fight this, we install large intercoolers and they work. But to work even better, coat those same parts with a dispersant, including the UIM.

If you try to insulate the UIM with a ceramic barrier, you will just trap the heat inside, causing your AITs to rise. If you don't coat it at all, then the bare metal will also conduct heat, resulting in the same issue, higher temps.

I posted up what Engine Coatings recommended in an earlier post, and that is to use a dispersant on the UIM. They are one of the largest coatings companies in the US so they know their stuff. Click on the link in the post and scroll down to see what parts benefit from dispersants and the UIM is listed.

Here is what another coatings company posts about dispersants:

Thermal Barrier, Thermal Dispersant, Carolina Ceramic Coating, Raleigh, NC

See the sample pic with the UIM coated in a dispersant?

Another website:

Xtreme Performance Heat Coatings

"Effective on Brakes, INTAKE MANIFOLDS, Cylinder Heads, Oil Pans, Radiators, Intercoolers and more."

And one more:

Carolina Ceramic Coating - Thermal Dispersant Coatings

"Effective on brakes, air conditioner condensers, cylinder heads, evaporator core, heat exchangers, INTAKE MANIFOLDS, intercoolers, oil and transmission pans, radiators, rear ends, valve springs, lighting equipment, transmission and transfer cases, oil and trans coolers and more."

But the best info comes from a tech article off of the Techline Coatings website, the manufacturers of ceramic barrier and dispersant coatings. Techline supplies about 95% of the market, both OEM and aftermarket. They recommend the ioTus approach to coat the bottom of the manifold with a barrier and the top with a dispersant:

http://www.techlinecoatings.com/arti...ld_Article.htm

Neutron

iTrader: (10)

I'm using the black heat dissipation coating on my turbo compressor, upper and lower intake manifold. Looks great and hopefully helps keeps air temps a little cooler.

jutFD

iTrader: (2)

David, is there a reason you chose the coating over anodizing?

David Hayes

iTrader: (6)

^ Yes, for the ability to control temps. The ceramic barriers and dispersants can be an effective part of your temp control strategy. They also look nice too and I have had a "blacked out" engine bay for some time now.

I don't think anodizing has the same temp control effects.

jutFD

iTrader: (2)

Most of what I've read says black anodized aluminum provides good heat dissipation. I was thinking of going this route since there's no coating involved. Although, I can't remember the amount of dissipation with anodizing so the coating might do more

David Hayes

iTrader: (6)

No idea on how it would work. Would look pretty cool though

WANKfactor

iTrader: (1)

David, untill you can explain to me why you would want warmer intake manifolds or can make heat transfer work backwards, im not going to be making my intake manifolds more heat conductive.

[EDIT] I think the manufactures and suppliers are referring to V8 intake manifolds where the manifold sits inside the v and is drawing heat directly from the heads and block, but the air above is relatively cool.
A single turbo rotary is different in that apart from the one mating surface, the manifold and intake are suspended in (hot) air and usually a big glowing turbine housing adjacent.

ioTus

iTrader: (5)

Wankfactor, I felt the exact same way as you until I had my entire intake manifold coated in barrier and I drove it for the first time (before it flaked and seized my VDI and 6 port valves). It did not reduce temps, only slowed down heat soak.

The engine bay ambient temp was for sure cooler than the intake, which was too hot to touch, plus, you have the radiator fan and alternator fan moving air directly over the intake mani to potentially help with heat transfer. A barrier layer would trap in the heat and reflect the cooler moving air.

The dispersant layer would to a degree make the intake itself a bit like a radiator or intercooler.

After the first drive I realized my mistake and would have rather gone dispersant. I totally hear you tho, it's not immediately intuitive. I had to see it for myself to begin to understand.

-Geoff

Sgtblue

iTrader: (16)

Interesting discussion. Both have points. But I'm wondering how much any heat in the surrounding metal of the intake is going to influence IATs. As I understand it, the amount of heat transfer is dependent on temperature differential and time of contact. I just don't see there being much of the latter...unless at idle.

David Hayes

iTrader: (6)

To each his own. Interesting discussion and good points. I'd say I will report results but I have changed too much to know how much if any the coatings aid in lowering temps. Would have to have everything installed without coatings, test, and the retest with the coatings and that is too much for me.

Thanks to all for the civilized conversation.

WANKfactor

iTrader: (1)

^ exactly what I'm thinking too, apart from trying to shield the LIM from the hot turbo, i cant picture myself coating mine for anything other than aesthetics.

And david, thanks for the discussion, i hope i havent come across too rude or obnoxious.

ohnono

iTrader: (1)

These are indeed very valuable information for me! Thanks David Hayes and everyone. I actually called the shop today and told them to do dispersant for UIM. Hopefully they heard me correctly...

David Hayes

iTrader: (6)

Not at all, no worries. I'm no expert in ceramics and don't fully understand how the coatings work so it's always nice to have a civil conversation about this stuff.

Glad to help. Post up pics when you get the UIM back. I am about two weeks away from having my v-mount setup completed so will be sending over a pile of parts to the ceramic coating company. Here's my list by type of coating:

Ceramic Barrier
- Down pipe
- Turbo manifold
- Turbo AR - already done

Ceramic Dispersant
- Turbo journal bearing - already done
- Turbo compressor - already done
- Radiator
- Intercooler
- Intercooler piping