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I just picked up a new underhood heat barrier for my formula hood off eBay, paid about $38 and $6 for the plastic clips. Got it today and seems fine. I have a 5.3 turbo and my underhood temps are insane lol so I was hoping this would help. Got it from AM Autoparts and have gotten stuff before from them and it works. Looks like the same hawks and other places sell for 2x the price!
haha we've been chatting on your thread on LS1tech about your new cutout setup.
Not sure. I only drove once with it and the hood felt much cooler but I didnt have it full mounted in the cowl, engine got pretty warm (warmer than usual) but that could just be the humid air and traffic and the underhood basically covering the cowl for air to escape. I should be able to drive it for the next couple of days to get an idea of how its doing. I also thought about adding heat tape or DEI mat to help but If this works its alot cleaner and cheaper.
You realize that panel you have installed is an insulator and will increase underhood temperature?
I too have turbo LS heat retention strategy implemented and will gladly supply some tips if wanted
it should insulate heat from the hood (main objective) second keeping the heat off the hood and hopefully in the engine bay should allow the functional cowl and bottom back of the hood with seal removed to allow heat to escape at most speeds. The liner doesn’t “absorb” and hold heat as it’s basically just fiberglass. It also streamlines the underside of the hood so air escaping should be easier vs being sucked out of a million obstructive crevices.
If your the same kingtalon on LS1tech god help us... Supply if you must.
it should insulate heat from the hood (main objective) second keeping the heat off the hood and hopefully in the engine bay should allow the functional cowl and bottom back of the hood with seal removed to allow heat to escape at most speeds. The liner doesn’t “absorb” and hold heat as it’s basically just fiberglass. It also streamlines the underside of the hood so air escaping should be easier vs being sucked out of a million obstructive crevices.
If your the same kingtalon on LS1tech god help us... Supply if you must.
If all the village people get together and agree that they all dislike that scientist on the hill with the telescope and that he should be burned like a witch because he is trying to show everybody the planets revolutions around the sun... of course you just blindly become one of the masses and go along with it right?
Try thinking for yourself, become an individual. Use your own brain to determine fact from fiction; and when presented with math you do not understand, instead of 'hes a nutjob because I do not understand math' try something else?
Heat flow in a system can be modeled like anything else in engineering practices. The issue under a hood is that the system is open to the environment and heat can leave whenever it wants (difficult to account for mathematically).
The two basic kinds of surfaces in an engine bay are reflective and absorptive. anything reflective is shiny for infrared light to reflect from, so dark fiberglass is obviously absorptive and will increase in temperature until it meets the temperature of surroundings.
Ill dig up some old posts if I get time to better explain
If all the village people get together and agree that they all dislike that scientist on the hill with the telescope and that he should be burned like a witch because he is trying to show everybody the planets revolutions around the sun... of course you just blindly become one of the masses and go along with it right?
Try thinking for yourself, become an individual. Use your own brain to determine fact from fiction; and when presented with math you do not understand, instead of 'hes a nutjob because I do not understand math' try something else?
Heat flow in a system can be modeled like anything else in engineering practices. The issue under a hood is that the system is open to the environment and heat can leave whenever it wants (difficult to account for mathematically).
The two basic kinds of surfaces in an engine bay are reflective and absorptive. anything reflective is shiny for infrared light to reflect from, so dark fiberglass is obviously absorptive and will increase in temperature until it meets the temperature of surroundings.
Ill dig up some old posts if I get time to better explain
So your therory of reflective and darkness does not actually apply to everything. Ceramic coatings for one are and can be both shiny and not shiny, they also come in black and other colors. As the barrier placed between the turbo and hood has created a barrier, and between the hood liner and hood is another barrier called air. If the insulation reflects or obsorbs the heat vs the hood it works as intended. The heat is not transferred to the hood and the liner creates a smooth surface (the hood without the liner has a bunch of pockets where the surface of the hood meets the underside bracing. This would be hard to pull air out of it. The hood has a small cowl and thus air rushing over it will create a negative pressure at the cowl causing the air to be sucked out of the engine bay. The liner covers 90% of the underhood and it all funnels up to the cowl, so it should make the heat that is not absorbed and suspended below the liner thus has a easier path outside of the hood and thus the engine bay.
so thinking for myself (ignoring your theories) with the heat barrier my hood was considerably cooler. My hood above the the turbo with no insulation was and has been in the 250+ range on the outside surface of the hood with a IR heat gun hot enough where I can’t put my hand on it for more than a quick tap. After hood insulation I can put my hand on it and hold it there all day. It’s much less hot. While doing the hood insulation tests the engine temps did not rise, and the IAT temps have not been affected.
Most of the time when I read your responses they are over complicated and all over the place (the term KISS comes to mind). Book smart doesn’t mean intelligent.
I never said the hood would be warmer. I said the insulation would trap heat in the engine bay, which is typically where we don't want it.
And that is true.
I've taken similar measures for my own setup. I even made a video where I use a heat gun and measure temps, add insulation, etc.. if you are interested.
Book smart doesn't help with cars at all. Everything I know how to 'do' to a car comes from experience. The books just help explain stuff to people that reject explanations.
What you've done to the hood is a good measure for keeping the hood cool. however you must realize now that the hood is cooler that the heat which it used to transfer and dissipate must be somewhere else instead... You've essentially turned the hood from being a heat sink (allowing the heat to transfer from hood to atmosphere) and turned it into an insulator (keeping more heat trapped under the hood).
So your therory of reflective and darkness does not actually apply to everything. Ceramic coatings for one are and can be both shiny and not shiny, they also come in black and other colors.
My observation about reflective materials was meant to be general. Ceramic coating are insulators; the external surface is negligible with respect to it's intended purpose (which is to trap heat IN something, or keep heat OUT of something). The reflective shiny ceramic coatings merely go one step further and reflect heat of the IR spectrum away (which never happens to a manifold since the manifold is the SOURCE of the heat in majority of applications) although you might suggest that a shiny coating would help reflect the heat which was reflected back from other objects in the engine bay... but I digress since again it is negligible with respect to the surface temperature of the coating on a hard running engine compared to it's surroundings (i.e.1200*F manifold tube vs 140*F reflective surface in the engine bay, such as an intercooler tube)
I never said the hood would be warmer. I said the insulation would trap heat in the engine bay, which is typically where we don't want it.
And that is true.
I've taken similar measures for my own setup. I even made a video where I use a heat gun and measure temps, add insulation, etc.. if you are interested.
Book smart doesn't help with cars at all. Everything I know how to 'do' to a car comes from experience. The books just help explain stuff to people that reject explanations.
What you've done to the hood is a good measure for keeping the hood cool. however you must realize now that the hood is cooler that the heat which it used to transfer and dissipate must be somewhere else instead... You've essentially turned the hood from being a heat sink (allowing the heat to transfer from hood to atmosphere) and turned it into an insulator (keeping more heat trapped under the hood).
steel is a poor conductor of heat. The hood was and will stay hotter for longer. As the hood retains heat it also heats the air around in (both inside and outside) this compounds the problem.
Increased engine bay temps would be reflected in increased engine temps and IATs. Since the engine bay is now theoretically hotter everything inside it will be as well. This is nnot reflected in my data and logs. I think the issue is you think the engine bay is sealed and it is not. The air is being vented as it naturally escapes the bay through the hood cowl and base of the windshield. At speed the bay heat is pulled out. It’s not insulated and sealed were there is no way for the heat to escape.
steel is a poor conductor of heat. The hood was and will stay hotter for longer. As the hood retains heat it also heats the air around in (both inside and outside) this compounds the problem.
Increased engine bay temps would be reflected in increased engine temps and IATs. Since the engine bay is now theoretically hotter everything inside it will be as well. This is nnot reflected in my data and logs. I think the issue is you think the engine bay is sealed and it is not. The air is being vented as it naturally escapes the bay through the hood cowl and base of the windshield. At speed the bay heat is pulled out. It’s not insulated and sealed were there is no way for the heat to escape.
thanks for trying to think about it first. Honestly for every action there is a reaction. You may not 'see' the difference in your sensing efforts but there is a difference, even if negligible to us.
A change to underhood temps does not necessarily reflect in engine coolant or IAT. That would depend heavily on other factors. For example in many cars the IAT is after an intercooler, which is after several feet of plumbing, which is after a compressor that runs 200-300*F. So it depends more on the flow rate of air (thus the coolant vs cts bias for low airflow flow rates in the GM ECU) and compressor outlet temps, and intercooling, than the underhood temperature (which is typically always less than compressor outlet), as fast moving air can move through the pipe fast enough to avoid absorbing heat from the pipe, if the pipe is hotter than the air, which is another variable.
As for coolant temp, if you notice that the underhood temperature is 140* of radiative surfaces with an enormous air gap to it's 180-200*F coolant. The exchange there would actually cool the coolant, since the air is cooler (even when warmed by underhood temps it still isn't hitting 200*F in the space near the radiator, a location of significant head exchange)
Insulation and reflective measures could be used effectively in any automotive setting. Typically high heat retention is associated with increased engine efficiency, as are higher temperatures, automanufacturers have been raising the standard coolant temperatures since the 'old days' from what we recognize as approx 180*F~ to around 235*F in modern vehicles as an effort to improve economy (efficiency).
It just so happens that our goals are slightly out of line with theirs. While they are looking at the engine model from the perspective of it being a docile daily driver, we are looking to increase cylinder pressure and the range over which that pressure is produced as we desire more torque. Therefore concerns about fuel quality become the over-riding aspect of increasing temperatures in search of efficiency, i.e. if you have an amazing fuel to burn (such as alcohol) you won't care so much about the high temperature outlet of a compressor at high flow rates (400*F~) because the fuel will tolerate that temperature, so you wouldn't want an intercooler (lowers power in that instance) or any kind of water injection (absorbs heat, robs power). On the other hand, if using poor gasoline fuels, the intercooling and water injection (power robbers) are necessary in order to push output beyond a certain level where the fuel would normally be unsafe. Give some to get some I guess.
That said, what you are dealing with on the hood insulation isn't so much a heat-retention, fuel related concern in my opinion. It is more of a overall 'system heat rejection' you are trying to build in effort to completely control the heat flow once the heat is rejected from the engine and it's parts and is no longer useful. The reason this is important is yes, something with the IAT and CTS, sure you can think of it that way. However the REAL issue is overheating of components such as exhaust tubes and the car chassis. For example the maximum inlet temperature to many modern turbines is around 1350*F. Adding insulation (ceramic coats, heat wrap, blankets) will raise this temperature. Understanding the difference between rejection of useless heat and retention of desirable heat is where I was going with this. The hood insulation for example is a poor way to 'improve the efficiency of the engine' because it involves retaining heat which is already useless to the engine. On the other hand, exhaust wrap insulation does a great job of keeping heat in the exhaust tube, where it is useful for improve exhaust gas velocity and expanding the exhaust gas to fill a turbine. I am not saying you did not need or want the hood insulation; I am only pointing out (from the start) that it is an insulator and will, overall, increase underhood temperatures, to some extent. I guess maybe I misread the thread title 'underhood heat barrier' and thought that you were thinking it would lower underhood temperatures, when you really meant that it would reduce under HOOD temperatures (literally the temp of the hood, not the temp under the hood). Hopefully this is either things you already know or some tid-bit of info you could use to further improve the heat control strategy in your vehicle.
Let’s agree to disagree. While the hood temps have dropped the engine compartment temps have also not increased. The cooling system above thermostat opening temp is essentially a open loop, the temp can not go below Tstat temp as coolant doesn’t circulate through the rad. Above Tstat opening temp the only thing controlling temps is airflow (speed and fans) and how much heat the engine creates and thus capacity of the cooling system and radiator can shed the BTUs to Create a range called “operating temp”. The air temp, engine temp and everything else affects the “delta” temp or essientially the difference between the outside temp and engine temp which is what the radiators job is. Converting engine heat to the incoming air thus cooling it off. As ambient temps increase the delta temp changes. This is due to the change in low and high (ambient and engine). So a 50 degree day engine temps might not ever reach 200* this is due to the engine still putting out the same BTU but the low ambient temp has lowered the delta temp. Now the ambient is 90* thus a 40* difference and the engine now hits 210-220*F as the hotter ambient temps have changed the delta temp and the hotter air has shifted the delta higher from ambient to engine temp range thus the radiator is essentially less efficient (not exactly but its working off a higher base temp differencial) so the engine temps increase due to increased ambient temps.
If the engine bay is “hotter” that means everything in contact with it also is, added bay heat will heat soak the engine, intake tubing, turbo, radiator blah blah. Bay Heat will transfer to everything the same way radiators transfer heat to the air, it soaks in it, the temp differential in the bay also affects everything else. An increase in engine bay temps will be directly affected in the IATs and engine temps. If the turbo is hotter the charge is hotter, the temp differential from the intercooler increases (hotter IATs but same ambient) thus the charge leaving the intercooler is higher, compounded via the hotter intake tubing back in the engine bay and intake manifold and engine itself. Heat will and always will transfer from the confines of the engine bay (unless no hood is used) even if it’s a smaller amount the sensors will show an increase in temps as a hotter engine bay will compound the heat it produces till the new delta temp is reached.
The threads original intent was to provide my experience with adding a hood liner (at a great price) and how it has affected temp of my hood. It has positively lowered my hood surface temps and I believe has also made my engine bay more efficient at removing heat from the engine bay by smoothing out the air flows path to the hood cowl.
for linear insulation ordinary differential equation
x˙= F(x, y)
x˙= f(y − x)
linearized to ODE means
x˙= k(y − x)
where k is a constant now,
so
x˙+ kx = ky
where ky is the input temperature
rate of change of x (temperature) is a function of the difference between temperatures (y and x) and not the temperatures themselves.
I'm not even sure what you think my I am disagreeing with. I never disagreed with you about the thread topic. I just pointed out that you added insulation to the engine bay because you meant 'reduced under hood temperature' not 'reduced underhood temperature'. One means the temp under the hood which you have increased and one is the temperature of the surface of the hood exterior which you have decreased at the other's expense. I believe you have accomplished what you set out to do was only making an observation and if you wanted some help with insulation further I am happy to help.
Wow! That's waaaaaaay too much info. I also run a turbo car and understand installing a hood insulator to prevent the hood from getting so hot. Anything you can do to increase under hood airflow would be your best solution. Removing any factory hood seals and installing heat extractors will be your best bet. Sorry no formulas to back it up.
10-02-2018, 10:00 PM
