Engine bay firewall heat shields

[jcraigau]

Hi Guys,

I'm currently lining my engine bay in aluminium and wanted to know what others have done to stop heat soak coming into the footwells and cabin.

I've found the following;
for inside the cabin Kool Mat thermal heat shield, aircraft insulation, fireproof material, race car insulation, firewall
for inside the engine bay Zero Clearance is a premium quality peel and stick heat shield material, under body engine bay heat

Other options I've considered;
- Spray-On Insulation - Automotive Insulation Coatings | LizardSkin
- Carbon Fiber Heat Shield | Heatshield Products
- Dynamat.com | Dynaliner for Automotive Use

I've heard everything from plate the engine bay then apply the heat protection.
Place the protection against the fibreglass firewall and then plate it with aluminium
Just put the protection straight onto the fibreglass and forget the plating
Just go with aluminium and forget the protection.

Some conflicting information, so keen to hear what others have done, what they learnt, and what would they do if they had to do it again.

Thanks,
JC

[Modena]

I have put aluminium sheets on the foot boxes with a 5-7mm air gap. Many learned people have done the same thing with mirror finish stainless and have not had any heat issues with this setup. I used 1.2mm aluminium, a lot of the stainless setups are 0.9mm stainless.

I used aluminium because according to my understanding it will reflect heat better than stainless. The mirror finish on the stainless does nothing to aid reflective properties, it is purely for aesthetics if that is your bling thing.

My setup is of course as yet untested as I haven't even fired my engine yet.

[gjkrv8]

Hi Jamie, I used the stick on stuff straight onto the footboxes from the engine bay side.

My theory is to insulate on the side of the heat source - e.g. stop it on the outside not the inside of the footboxes.

Got it from Rev race gear - not cheap but worked a treat. Its an aluminium outside with some heat insulation material of about 3 or mm.

Before that it was pretty unbearable.

One trick I did was to heat shield some of my chassis rails and underfloor as the underbody exhaust was heating up the rails and radiating through to the sides of the foot boxes. It depends on your setup of course.

Now I reckon my footwells get about a hot as my Suby Liberty. which is not much.

Hope your choice (of which there are many) works out for you. Cheers Gregg

[deano59]

My old cobra i used the stick on insulation and then used 2 mm alloy that was mounted with a 5 mm air gap . I used the same stick on on the inside of the cab my foot box and trans tunnel never got uncomfortable at all . I had a friend who used nothing his car always felt like it had the heaters on and was not pleasent on warm day at all .
cheers dean

[David Hodgson]

I sandwiched air-conditioning ductwork insulation between the fibreglass and the aluminium panel. It was like the pic below but about 12mm thick and no foil, just the black backing. Its cheap as chips and worked a treat.

[mando s]

I used LizardSkin on my Cobra. I sprayed on about 15 thin coats until it reached the thickness of a credit card. Fantastic product that dries hard but flexible that can be sanded and painted if needed. I sprayed the hole interior including the tunnel firewall and footboxes.

Regards.

[deano59]

My old cobra i used the stick on insulation and then used 2 mm alloy that was mounted with a 5 mm air gap . I used the same stick on on the inside of the cab my foot box and trans tunnel never got uncomfortable at all . I had a friend who used nothing his car always felt like it had the heaters on and was not pleasent on warm day at all .
cheers dean

[Paintwerks]

My Pace 427SC uses a stainless panels in the engine bay, with a 2mm air gap on top of aluminised-face, fibreglass heatshield material. I don't know the name of the product as it was supplied in an unpackaged/unbranded roll. This material is affixed using RTV401 high temperature silicone sealant.

The inside of the cockpit has covered in a layer of Dynamat-type self adhesive bitumen-impregnated insulation.

[Tommy]

I'm going to try to be helpful without being too technical. The three major means of heat transfer in your car will be conduction, radiation and convection. Conduction occurs when something hot comes into contact with something cooler and transfers its heat to the cooler object. Your solution is to make sure nothing hot comes into direct contact with your cockpit. Radiation is mostly associated with very hot objects like exhaust pipes producing a heat you can feel from a distance. They are actually glowing light in a part of the spectrum we feel rather than see. You can block that light the same way you'd block any other light, with an opaque shield (e.g., aluminum plate).

Convection is when air is heated by contact with the heat source and then circulates to come into contact with a cooler object to which it will transfer its heat. This is what we feel when warm air from our car heater blows out of the dash. Circulating air is pretty good at transferring heat. Stationary air is not very good at transferring heat. That is why a lot of home insulation is little more than material trapping pockets of air that cannot circulate around inside the insulation.

With the science lesson complete, the bottom line is that for optimum insulation of your car you'll want to guard against all three ways heat can seep in. First, don't let hot stuff contact anything that will contact the inside of your cockpit. Second, have a radiation barrier between the cockpit and the hottest parts of your engine. A simple sheet of foil will work if it can withstand the other demands of your car. Finally, put a layer of insulating material between the radiation barrier and the cockpit. As someone said above, it could be as simple as a layer of dead air between the aluminum barrier and the firewall. A layer of foil faced bubble wrap would also work.

I hope this helped.

[trularin]

If I might add, I had to place a heat shield for my master cylinders. Amazing difference - the headers are basically under them used to heat them to the point I could feel a diffence in pedal. I formed an aluminum shield with a shock absorbing end. Before test I could not grab the MCs after a strong run is 80+ F temps. Now they are air temp cool.

If you are putting in the shields, might want to think about doing this while all the stuff is out of the way.

Hope this helps.

Tru

[jcraigau]

Thanks to everyone that has responded. Plenty of food for thought. I'm glad I reached out before starting down a wrong path.

One other place I have seen shielding used is under the inner guards above the exhaust exits to stop paint from fading with the excessive heat from that area.

[Tenrocca]

I've mentioned this many times before. I have 5mm cork (tiles) sandwhiched between the fibreglass and aluminium panels. Inexpensive and cool as a cucumber.

[kevins2]

In addition to the insulating ideas, you may consider ways to vent more heat. The photo below is from ERA's website and shows screened vents in the wheel wells.



I also have aluminum panels around my headers that force more of the heat toward these vents.

Another idea is to not make your hood weather stripping continuous so a bit more heat can escape. If any of this is interesting to you I can get some photos.

Good luck with your build.

Kevin

[Auswallaby]

Originally Posted by Tenrocca

I've mentioned this many times before. I have 5mm cork (tiles) sandwhiched between the fibreglass and aluminium panels. Inexpensive and cool as a cucumber.

How does it standup to the weather over time?

[Tenrocca]

They aren't exposed at all. Covered in the aluminium and sealed at the bottom edges with silicone.

[Morris]

Here's what we found the best for rejection of heat in the drivers compartment. It works great and it's very important to keep the driver cool. Heat can cause many driver errors. To the point I've seen one driver drive into a stopped car along side of the track.

Rubber Silicone base and then SS as the outer surface on both sides of the foot boxes.

[Morris]

Here's the difference in the fake SS and the Real.

[Morris]

Lot's going on in these photos.

[patty442]

Morris I sent an email several months ago about a project. Have not heard from you. Please send a pm with your telephone contact information. Thank you

[Morris]

Originally Posted by patty442

Morris I sent an email several months ago about a project. Have not heard from you. Please send a pm with your telephone contact information. Thank you

I don't expect anyone to send me any messages, so I never see them.

Sent the info and will be glad to help out