Thermal dispersant asthetics?

[Spaceclam]

So after having filled up with $8/gallon 100 octane fuel and having NO pinging, i can say i REALLY liked it.

When the temperature drops from 60 degrees to 50 degrees, the pinging goes away almost completely.

Im entertaining the thought of blasting the PC (insulation) off my heads and replacing it with a thermal dispersant coating, in an effort to imitate the effects of cooler weather on my engine's behavior. I feel a realistic result is a drop of 10, degrees to be conservative.

Dispersant coatings are always black. So, i've photoshoped my heads black, what do you think?

-Clam

 

[GuzziMoto]

I would do the valve covers as well. More for looks but also for effect.
And I would coat the combustion chambers as well while your at it. As my mother always told me, "if a jobs worth doing, it's worth doing right". It would be crazy to go that far with trying to shed heat and not try to reduce the amount of heat absorbed by the head in the first place.

 

[Spaceclam]

well doing the valve covers kind of brings out the 8v look, which i dont like so much. Also, i'm kinda weary about coating my combustion chambers.

basically, CC coatings seem to be marketed towards "keeping the heat in the combustion chamber", as in, a hotter combustion cycle, for more power. What i DONT want, is to have a hotter combustion temp heating up a thermal barrier coating which gets hot, but doesn't transfer heat and thus gets hotter than the bare aluminum walls of my CC did in the first place.

Nobody has been able to address that concern for me, because typically, these coatings are either A, applied to race bikes with much more modern piston/CC designs running leaded race fuel, or B, applied to tricked out harleys just for bragging rights.

If i do a thermal dispersant, i CANT go wrong. the question is just whether or not it lowers my temps enough to do anything (is 10-15 degrees of head temp enough?).

And how it looks. I'm kinda undecided.

 

[GTM®]

If i do a thermal dispersant, i CANT go wrong. the question is just whether or not it lowers my temps enough to do anything (is 10-15 degrees of head temp enough?). And how it looks. I'm kinda undecided.

I'd say 10~15 degrees lower wouldn't be worth the headache and expense. Why not just strip the heads and leave them bare metal? The black heads have been done by many OEM's over the years, including Guzzi. I don't mind it either way.

 

[Spaceclam]

i could just leave it bare, but then the heads will look a LITTLE different than the jugs, unless i pull those again too.

I guess as long as i have it off, it's not too much more headache to have them coated, but it would probably cost me another $200. Not a HUGE sum of money, and worth it if it helps. Im just not sure it will.

i guess im just afraid of pulling shit apart again, blasting it only, sticking it back on and realizing that it helps, but i should have coated things because it would have helped more.

Is there some real time way to measure my head temps, or record them, as i ride? i'd be curious to know the difference between 50*F ouside and 60*F on the heads. I guess that would answer my question.

 

[GuzziMoto]

basically, CC coatings seem to be marketed towards "keeping the heat in the combustion chamber", as in, a hotter combustion cycle, for more power. What i DONT want, is to have a hotter combustion temp heating up a thermal barrier coating which gets hot, but doesn't transfer heat and thus gets hotter than the bare aluminum walls of my CC did in the first place.

The theory as I understand it behind coating your combustion chamber is that it slows/reduces the heat transfer from the air/fuel mixture burning in the chamber to the cylinder head. This means that more of the energy (heat) is applied to pushing the piston down (power) and the next cycles air/fuel mixture will be cooler in the chamber until it is ignited as there is a reduced amount of heat being radiated back into the chamber from the head. It also means higher exhaust gas temps since less heat is absorbed by the head then more is going out the exhaust valve. If it does what it is claimed to do, reducing heat transfer, it is a good thing and something that may help you. How big a difference it would make I don't know.
Something else to keep in mind is that it is generally accepted (for reasons that I only partially understand) that heat will radiate better from a dull black surface then it will from a bare aluminum surface. That is why some heat sinks are anodized black. It is not an absolute rule, I don't think, but a good generalization.

 

[Spaceclam]

after contacting several companies, the usual answer tends to be "i dont know". They are aimed at reducing heat TRANSFER, and the properties of heat ABSORBTION by the coating doesn't seem to be a common knowledge, even amongst application shops.

That is true about black surfaces, which is why dispersants are always black.

 

[Brian UK]

If these coatings are aimed at reducing heat transfer then surely that's the last thing you want as it will reduce the cooling effect not improve it.

 

[guzzi jon]

Yo Clam man,
Didn't the three terblanche concept bikes shown have a heat exchanger in front of the valve covers with a line running to the head to reduce temps to allow higher compression and allow more power? Seems I recall the picture showing the sucker hooked up to an 8V engine, dont know if there is anyway to plumb in an oil cooler that will lower the temp of the oil cooling the head/valvetrain on a 2V griso, but you never know. If the change shows up with a shift in ambient air temp of ~15 degrees, seems that would not change engine temp that much, but with the odd ball sensors and shit on guzzi's it could effect F/A numbers....

carbs and a distributor, yeah, thats the ticket

Keep on experimenting, and swing by Ontic sometime, we have an engineer that designed recip airplane engines and he's well versed on this kind of stuff, might have some good ideas

 

[rturo]

after contacting several companies, the usual answer tends to be "i dont know". They are aimed at reducing heat TRANSFER, and the properties of heat ABSORBTION by the coating doesn't seem to be a common knowledge, even amongst application shops.

That is true about black surfaces, which is why dispersants are always black.

When I checked out Ceramic Coating of downpipes I got the same response about heat loss - seems it is used to remove some localised underbody temperatures in tuned cars where other components are close to the exhaust heat, but does this by increasing the heat retained within the pipes. I figured this must also lead to increased head temperature around the exhaust valves and head which put me off as my aim was as much to lower temperature as the look.

I've seen copper coated downpipes which develop a multi-toned effect when heated and wonder if it is possible to coat alloy heads with copper - I've used copper computer heatsinks which allow you to get away without a fan because of the efficiency of copper in transfering heat..

Art :huh:

 

[GuzziMoto]

If these coatings are aimed at reducing heat transfer then surely that's the last thing you want as it will reduce the cooling effect not improve it.

No, I think you missed the point. The intent of coating the inside of the combustion chamber is to reduce the amount of heat the head absorbs from the combustion process by coating it with a material that does not transfer heat well. If you reduce the amount of heat the head picks up from combustion you will lower the temp of the head. The head picks up more heat from the combustion chamber then it sheds to it. But by coating the chamber with a material that does not transfer heat well you will also reduce the temp in the chamber before ignition because the head will transfer less heat to the intake charge in that brief moment before ignition since the head temp is lower to begin with and what heat it does have it won't transfer to the air inside the chamber as fast.
The coating on the outside of the head is there to increase the amount of heat being transfered. That is self explanatory.

 

[Spaceclam]

Jon,
I have, for quite some time toyed with the idea of watercooling my heads. I could wrap some copper tube inbetween the fins, which are about an inch and a half deep so nobody would notice. There is room under the tank for a pump, and im sure i could fit a small reservoir somewhere.

i have also thought about using the oil cooling method. The only issue i see, is that it requires a fair amount of pressure to shove oil through the little holes in the rockers and in the main bearings, and im afraid that plumbing some cooling oil around the heads might just short-circuit the system, and cause cam/bearing failure due to lack of oil pressure.

Guzzimoto,
That i get, and the intake charge temp is a good point. hadn't thought of that.

But what i mean is, just because the coating doesn't TRANFER heat to the head, doesn't mean the coating itself doesn't get REALLY hot. The question that shops cant seem to answer is, does the temperature of the coating exceed the temperature of the bare walls of the combustion chamber?

As in, we all agree the temperature measured at the head will be lower. But will the surface of the combustion chamber be hotter or cooler?

The more research i do, the more conflicting answers i find. some say "fueling adjustment required due to hotter combustion chamber temps to prevent pinging" and others day "reduces pinging by lowering head temperature".

Of course, ceramic coating things means taking my heads apart COMPLETELIY (valves, guides, everything) which i dont have the tools to do, and am not interested in doing myself.

 

[rturo]

If these coatings are aimed at reducing heat transfer then surely that's the last thing you want as it will reduce the cooling effect not improve it.

No, I think you missed the point. The intent of coating the inside of the combustion chamber is to reduce the amount of heat the head absorbs from the combustion process by coating it with a material that does not transfer heat well. If you reduce the amount of heat the head picks up from combustion you will lower the temp of the head. The head picks up more heat from the combustion chamber then it sheds to it. But by coating the chamber with a material that does not transfer heat well you will also reduce the temp in the chamber before ignition because the head will transfer less heat to the intake charge in that brief moment before ignition since the head temp is lower to begin with and what heat it does have it won't transfer to the air inside the chamber as fast.
The coating on the outside of the head is there to increase the amount of heat being transfered. That is self explanatory.

Seems something wrong to me about stopping the head and cooling fins on an aircooled bike getting the heat transfered to them as a way of reducing head temps. I know the goal is to reduce head temp but other things (like friction) being equal, the heat from the charge produced will remain the same and you are restricting one path for it to escape. Won't it mean that before the extra heat can go out of the downpipes then it will be absorbed by the piston, valves, conrod etc ?

Isnt the theory behind the heat converters on the new show bikes that it gives a efficient ecape route for the heat in the heads?


Art :blink:

 

[GuzziMoto]

Guzzimoto,
That i get, and the intake charge temp is a good point. hadn't thought of that.

But what i mean is, just because the coating doesn't TRANFER heat to the head, doesn't mean the coating itself doesn't get REALLY hot. The question that shops cant seem to answer is, does the temperature of the coating exceed the temperature of the bare walls of the combustion chamber?

As in, we all agree the temperature measured at the head will be lower. But will the surface of the combustion chamber be hotter or cooler?

The more research i do, the more conflicting answers i find. some say "fueling adjustment required due to hotter combustion chamber temps to prevent pinging" and others day "reduces pinging by lowering head temperature".

Of course, ceramic coating things means taking my heads apart COMPLETELIY (valves, guides, everything) which i dont have the tools to do, and am not interested in doing myself.

Sorry, Spaceclam. My comments were directed at Brian UK.
As for the idea of head temps, if you coat the combustion chamber with something that does not conduct heat as well as aluminum (which conducts heat very well) you should see a reduction in temp both outside the chamber in the head as well as inside the chamber before ignition. Think of heat as energy (which it is). If there is less energy absorbed into the head from the combustion chamber then the amount of energy in the head will be reduced (lower head temp). The effect on the temp in the chamber is two fold, there is less energy in the head to flow back into the chamber prior to ignition and what energy there is will flow slower as the coating that slows energy (heat) transfer slows it in both directions. It is possible that there may be a very thin layer on the surface of the coating that ends up being hotter then the aluminum surface of the uncoated chamber. But you have to look at it as energy capacity and energy transfer, and it would take very little energy transfer to cool off this thin layer of the coating as the energy capacity of such a thin layer is very small. So its capacity to heat up the intake charge would be reduced overall.
If something, a coating or whatever, can slow down the transfer of heat and you apply it to the interior surface of the combustion chamber then the temp of the head and of the intake charge will be reduced. conducting heat is a two way street. Things that conduct heat faster heat up faster and cool off faster. Heating up is a function of absorbing (transferring) energy from something else and cooling off is giving that energy (transferring) to something else. With a few exceptions materials that do one better also do the other better, and things that are slower at one are slower at the other.
How big a difference it would make would depend on how well the coating actually slowed the heat transfer. If the coating was able to actually stop the transfer of heat altogether (it's not, but just imagine it could) then head temp would drop to just above ambient temp and the temp of the intake charge just prior to ignition would be about ambient. I say this only to use an extreme example to illustrate the effect.

 

[GuzziMoto]

Seems something wrong to me about stopping the head and cooling fins on an aircooled bike getting the heat transfered to them as a way of reducing head temps. I know the goal is to reduce head temp but other things (like friction) being equal, the heat from the charge produced will remain the same and you are restricting one path for it to escape. Won't it mean that before the extra heat can go out of the downpipes then it will be absorbed by the piston, valves, conrod etc ?

Isnt the theory behind the heat converters on the new show bikes that it gives a efficient ecape route for the heat in the heads?


Art :blink:

Think of it as reducing the amount of heat that the fins have to dissipate. You cannot stop heat from transferring to the head but if you reduce it then the head will be cooler and have less heat that it has to get rid of.
And yes, when you coat the head you should coat the piston as well. It would have the same effect as coating the head. Coating the valves is less tried and true but also viable. I have even seen people coat the exhaust port. Anything you do that reduces the amount of heat transferred into the motor from the combustion process will reduce the temp of the motor and increase the temp of the exhaust gases, which, before they get expelled out the exhaust port will cause the piston to be pushed down the bore that much harder. That is, in the end, the whole idea.
The "theory" of the heat sinks on the show bikes remains to be seen. It is likely just a styling exercise by a guy with no engineering background. Best of luck on that one to Guzzi.

 

[Spaceclam]

i suppose if i had the tools/time/money required, i could take the heads apart, have them chemically stripped, dispersants on the outside, ceramic inside. But i dont.

I do notice it pings more when my tank is full. If i ever get my battery welder together, i'll have a 2.5 lb lithium battery replacing my 14 lb AGM (equivelant to about half a tank's worth of weight) so we'll see how i end up. LIke i said, i may end up doing it over the summer, if it starts pissing me off.

As far as the looks go, i think i like the black heads/silver jugs.
-Clam

 

[rturo]

Seems something wrong to me about stopping the head and cooling fins on an aircooled bike getting the heat transfered to them as a way of reducing head temps. I know the goal is to reduce head temp but other things (like friction) being equal, the heat from the charge produced will remain the same and you are restricting one path for it to escape. Won't it mean that before the extra heat can go out of the downpipes then it will be absorbed by the piston, valves, conrod etc ?

Isnt the theory behind the heat converters on the new show bikes that it gives a efficient ecape route for the heat in the heads?


Art :blink:

Think of it as reducing the amount of heat that the fins have to dissipate. You cannot stop heat from transferring to the head but if you reduce it then the head will be cooler and have less heat that it has to get rid of.
And yes, when you coat the head you should coat the piston as well. It would have the same effect as coating the head. Coating the valves is less tried and true but also viable. I have even seen people coat the exhaust port. Anything you do that reduces the amount of heat transferred into the motor from the combustion process will reduce the temp of the motor and increase the temp of the exhaust gases, which, before they get expelled out the exhaust port will cause the piston to be pushed down the bore that much harder. That is, in the end, the whole idea.
The "theory" of the heat sinks on the show bikes remains to be seen. It is likely just a styling exercise by a guy with no engineering background. Best of luck on that one to Guzzi.

So there should be a a power boost due to less energy wasted as heat ? ..

I thought the heat exchangers on the concept bikes were most likely pure style but it seems there is some real science - see http://www.ashonbikes.com/content/moto- ... heat-pipes.


Art

 

[GuzziMoto]

The power increase would likely be small, but yes, if the coating does slow heat transfer there would be a power increase.
So, they are suggesting that Guzzi is going to put AC units on their bikes, not for the rider but for the motor. And people think that they will work? I'm not buying that bike.

 

[Spaceclam]

people could have said the same thing about water cooling. If it works, it works.

I could probably drop my head temps a few degrees if i put a vaccum pump on my rocker box breather and put a hole with a filter somewhere on my rocker box, simply because there's a lot of moving parts and surface area up there under that box, but there is NO airflow.

 

[GTM®]

Andrew, give these guys a ping... they're moto-heads; raceenginecoatings.com