308 Footwell Temperature Measurements - Where the Heat Comes From

Its probably still hot due to the fact there is no insulation between the front area and the cockpit. I have a friend with a '80 GTSi that has been un-modified, and will get some images later this spring to show the difference.

 

Here is a couple of videos of the interior from a thermal camera.

[ame=http://www.youtube.com/watch?v=KRKyx2U6pD0]Ferrari 308 GTBi - Thermal Video - Interior 1 - YouTube[/ame]

[ame=http://www.youtube.com/watch?v=C-ajBU3jFLc]Ferrari 308 GTBi - Thermal Video - Interior 2 - YouTube[/ame]

 

Post 17-20 are missing?
Anyway I wonder if an injection foam insulation material would work here? Just thinking out loud. Would only need to make a few small holes.


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17-20 are on the web. Might be an iPhone issue.

As for the foam, you would have to panel the other side to create a cavity.

 

Not for me. Humm...

That could work well, ... if the floorbaord is where the heat is coming from. Jonny Law's thermal videos are awesome.

Video!!! Incredible. I take it you are using a thermal camera worth more than some of our cars. These video are really cool.

That front bulkhead is really looking nasty. It's still hard to compare though the heat coming from the floorboard.

A couple of spots which might be good to video:
- Top of the dashboard.
- Interior of front trunk.
- A pan across the floorboard from the accelerator pedal to the seat.

What we do about this all is still a mystery. HotShoe can just use cheap fiberglass wool for the gaps between the two floor layers, but the effect is still unknown. (I measured fairly low temperature on the rearward floorboard with my cheapie IR thermometer.)

Being fussy, it would be great if you could fix the maximum temperature to 120 or so, just to more easily see the really hot spots. Most of all, THANK YOU for taking the trouble to make the videos and posting them.

 

Yup it's a Tapatalk issue


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Thanks Brian.

My car does have a Dinamatt type material under the carpet, but you can tell where it stops. I have also placed Reflectex material between the cockpit and the front compartment.

I will get some images and video of my car when I am finished insulating the dash as well as video from a car that has not been touched. This should show the differance.

 

I replaced my timing belts. To drain the cooling system, I popped the lid off the front access port to yank off the heater hose. It was a good opportunity too to assess the practicality of insulating the front side of the footwell bulkhead.

Oh! The horror! The horror!

The photo below shows that there is really no practical way to insulate the front bulkhead from the forward side. It is a photo looking mostly upward and slightly rearward toward the bulkhead. At the top of the photo is the rear edge of the battery. Dominating the middle of the image are the coolant pipes, brake lines and the steering rack. The steering shaft connects to the rack at that flat plate to the extreme right of the photo. The bulkhead itself is traversed by a barely visible X-brace. It is even tighter than the photo looks.

All bulkhead insulation must be done from the cabin side of the bulkhead. Woe. The inferno shall rage.
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+1. Otherwise you have to remove a lot of hardware.

So is the Divine Comedy a Ferrari parked at the gates of Hell?

 

I was reading this with interest & looked up reflectix and there a quite a few websites indicating this type of material doesn't work. Snake oil is the term thrown around frequently. So what are the real world experience with using this on our 308's.

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I can't offer real world experience regarding Reflectix, but can provide a "theoretical" answer...

The 308 has cabin heat problems for two reasons:

1.) There are openings in the front bulkhead where hot air leaks directly into the cabin. Any product that can plug these holes – even duct tape – will eliminate this heat source. Judging from Jonny Law's photos, it even leaks in through the HVAC ducts.

2.) The front side of the front bulkhead is exposed to heat from the radiator. Because the bulkhead is simple fiberglass, that heat easily conducts through the bulkhead to the cabin. Insulation is needed. The measure of insulating capability of a product is its “R-factor”. The bigger the number the better. Another way to do it is to block hot air contacting the front side of the bulkhead in the first place.

Regarding Reflectix, in the 1960s space race, the Mylar ‘Space blanket’ was invented. Its shiny surface reflects back any infrared “radiant” heat. A human body doesn’t generate much infrared, so a Space Blanket is not really very warm (it probably works mostly by reducing evaporation of perspiration). A product like Reflectix is also only a simple reflector. It doesn’t have a high R-factor. A 308 bulkhead gets hot, but I don't think it would be hot enough for Reflectix to work very well.

I am no physics expert so be warned that the above may just be me blowing wind in my own INCORRECT understanding of how things work. Hopefully experts will chime in.

 

Unfortunately all heat is infrared energy. Maybe it might be easier to duct fresh air to the areas up front to cool them rather then try to insulate?


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I had not seen this thread before. Some observations from an old, retired aerospace,thermal guy and a short primer on heat transfer.

I loved the FLIR thermal images. We used one at work for experimental/verification purposes. Anyone posting new images should also include the color scale in the image.

Floor temperatures of 104 F are not very hot, only 5 F above body temperature. Outside ambient air temperature would be helpful in evaluating temperatures elsewhere.

A major heat source in the front bay are the front to back radiator lines. These lines should be insulated wherever possible as there is a lot of exposed surface area associated with them. Local air picks up the heat from the surface of the lines and spreads it throughout the front bay area. Round coolant tubes are easily wrapped and require a minimal amount of insulating material to be effective. This is good bang for the buck.

Heat rejected by the radiator should be shunted to outside ambient if possible and not allowed to come in contact with the cockpit bulkhead.

Fiberglass panels are a relatively poor heat conductor, but if you are only going through a 1/8-inch thick panel, that is not a large thermal resistance. It would be effective to insulate the inside of this panel, just under the carpet, and not worry about the front bay side, especially if access is a problem.

There are lots of insulating products that could be helpful and they can take many forms.

The important property to compare is the conductivity and thickness of the material between the heat source and where you don't want it to go. For insulation purposes, you want low conductivity. Diamond, silver, copper, aluminum are all high conductors. Aerogel, layered reflectors, foam, fiberglass batting, and air spaces are poor conductors.

Conductivity, (k) is a material property with typical units of BTU ft/hr sqft F or W/in C or W/m K. The lower the conductivity, the better the insulating properties. Home insulation is rated by R-value, the inverse of conductivity, or hr sqft F/BTU ft or simplified to hr ft F/BTU. High R or resistance is the opposite or reciprocal of high thermal conductivity.

Bill

 

Here is what I have experienced with this problem, which I no longer have.

1. The DOT front bumper deflects air away from the radiator forcing it to run hot.
2. Insulating from the inside of the cabin works.
3. Changing out the radiator to a larger unit, changing the front bumper to the bumper designed for the car, and insulating the cabin from the inside fixed this problem for me.

 

What great information. I'm very interested in lower the temperature in the cabin along with less road noise. Bill is this the right stuff? Aspen Aerogel Spaceloft Insulation Hydrophobic Mat 10" x 14" Sample 10mm | eBay

I would want to seal all the holes first. So there is no air leaking in. This alone I think will help a lot. Would you use 3m spray to apply it to the floor and firewall? Or double sided tape? Or should you insulate under the floor? Would you want to take the black tar stuff off the floor first or go overtop of it? Would you want to put dynamat over it or put the dynamat down first or don't use the dynamat at all?

 

George, how did you insulate you cabin and what did you use. Did you use a aluminum radiator or recore you old one? I have a 85qv euro.

 

Or reduce the amount of hot air reaching the front bulkhead. There are frame members just behind the battery which look like a good place to fasten a large plastic barrier across the width of the car. If a barrier could be installed there, it might make insulation unnecessary.

Generally, it seems like a good idea to reduce the amount of hot radiator air swirling around under the spare tire well. The hot radiator air doesn't just exit from the hood louvers. The flexible hoses connecting the cabin heater fans to the heater boxes pass diagonally, almost vertically, through openings on either side of the spare tire well. By adding a little length to them, they could be reconfigured so they pass through horizontally thereby creating considerable open space for radiator air to move directly out the wheel wells. This may improve cooling when the car is not moving as well.

If these changes were made, I am not sure if punching louvers in the lower access plate will improve or harm the temperature isolation. Superficially, it seems like a good idea.

I just hit the Aerogel website and couldn’t find anymore where they sell to ordinary customers. They used to sell mats which would have been perfect. Can’t argue about the quality of a product that is a spin-off from Space Shuttle heat shields.

 

Just for giggles, would one of you with more time than I consider creating a cardboard baffle under the spare tire area so that little or no air from the radiator can escape anywhere but the hood vents, under the car, or laterally from the louvered engine bay panels and do a before and after temp reading of the bulkhead?

That way one could get a rough idea of the amount of cabin heating coming from the radiator airflow right?

 

I have an '85 Euro and it was missing the second foam insulator on the underside of the bonnet. There is a long piece that contacts the top of the radiator up front, but there is a second, longer, U-shaped piece that contacts and seals the spare tire compartment. Replacing that foam piece made a huge difference on my car. The cabin is actually pleasant even in a drive across town in 100deg heat.

Just a thought, Franny

 

Hi offtheworkigo.

Yes, the Aspen Aerogel is one form of Aerogel.

The order or stack up of materials really doesn't make any difference. The electrical analog is a series of resistors in a circuit. It doesn't make any difference if a 3 ohm resistor is followed by a 10 ohm resistor and then a 7 ohm resistor. If you add them up, they are equivalent to a 20 ohm resistor. The order in which you add them up makes no difference, the end result is still the same.

I believe Aerogel is fragile, so you probably don't want to step on it or compress it. Against the bulkhead it would likely be fine, but probably not under your feet, unless protected in some way.

Bill

 

Still looking at this and found Zircoflex Form that might meet our needs. Looks to be available through multiple retailers.

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I will tell you that when I wrapped the supply and return lines from the radiator in Reflexix it dropped the temp in the front by 20 deg. Now this compartment was still hot considering the radiator is still pumping hot air in to it, but there was a difference. The Reflectix is basically a aluminum foil coated bubble wrap. The bubbles also help with an air pocket, but when I removed the Reflectix to try something else, some of the bubbles had popped due the the heat.

With all the AC equipment, heater cores and hoses. It would be easier to insulated from the cabin side.

I removed the pusher fans from the front and added two puller fans with a shroud which helped with the engine cooling, but the front compartment is still flooded with hot air. I even went so far as to add pusher fans to the fender grills. This helps but its also loud.

Would agree about insulating from the inside is easier.

As for the bumper, my is a euro so am not sure what effect this has. But would agree that limited air flow as well as a smaller opening will have an effect.

I actually created a bulkhead wall behind the battery made of Correx (a corrugated polypropylene material usually used for signs) that runs from the top to the bottom and side to side. It works well but the heat will eventually saturate the wall and everything behind it. The heater cores don't help either, even with the water flow completely disconnected the heat from the return line will heat the hoses. This is of course with the spare tire well removed.


I am also experimenting with different insulated hose ideas for the fresh air intake, but I have to figure out how to keep the heater cores cool first.

 

I used one of Ferraripilot's racing radiators built for the 308.

 

Has anyone looked into applying a radiant heat raducing barrier paint? This would fill in the little holes as well on the fire wall / floor board. This product says it reduces radiant temperature by 30 degrees. Dropping from 110 degrees to 80 degrees, I might be able to feel a little breeze of cool air from the air conditioner to bring down the temperature to mid 70s. Thoughts?

 

Just curious, did the 328s make any design changes of the types being discussed here to address the heat transfer problem?