Headers & Footboxes

[KevinW]

A few questions to those of you who have white GRP footboxes and FE headers.... your comments, as always, appreciated....

- how much air gap is there between your headers and the footbox? Im interested in the distance of closest approach/proximity of headers to footbox.

- have you protected the GRP with heat matting or some ali sheet?

- have you noticed any dis-coloration in the white gelcoat due to hear build up, or any adverse effects? I'm wondering what happens if you are stood in traffic idling, and the heat from those headers hitting the footboxes?

I only have a few (about 5mm clearance) one side. thinking of sliding in a stainless or ali plate heatshield and removing the GRP behind it (my footboxes are steel underneath the GRP).

[mickmate]

They are about 3/8 gap on the closest points. It is indeed common practice to heat shield them and the master cylinders below them. Stick on reflective thin insulating material is common to wrap the footbox. I have also seen and made reflective shields with an insulating jute type material sandwiched between them and the glass. I have seen fibreglass footboxes about cooked with what looks close to a fire inside with under felt and carpet material.

[Mdman352]

You mean discolored like this???



Moving the rearmost header away from the footbox will help with the heat issue and provide more room in the footbox.


I have Dynamat in the engine compartment as well as under the carpet. Nick Acton did my work.

[Dimis]

A simple fix may be to not only insulate the foot boxes themselves with Dynamat, but also to use an exhaust wrapping.

Check out lava wrap, or the foils in the link below, one of many brands.

Heatshield Products


PS: This anecdotally may reduce the life of your headers (but your only talking by a year or so, so you'll get 10yrs instead of 11yrs?), and the trade off is a cooler engine bay, and thus free power & increased efficiency as there's more O2 to burn in the intake

[mickmate]

I just used some of their lava mat on an exhaust/master cyl sheild. It looks good and seems to be working in the summer heat.

This top view of the foot box shows the insulation with a polished aluminum shield over it.

How's the heat Dave?

[mickmate]

I just used some of their lava mat on an exhaust/master cyl sheild. It looks good and seems to be working in the summer heat.

This top view of the foot box shows the insulation with a polished aluminum shield over it.

How's the heat Dave?

[GWL]

I'm building an FFR roadster and using a Ford 302 with Ford Racing shorty headers has allowed me to not only enlarge the footboxes but 'Super Insulate" them as well.

Inside is the enlarged aluminum footbox. Then, outside, I've added a layer of 10 mm of Pyrogel. Then an outer layer of .050" mirrored stainless steel sandwiched together with stainless button head bolts.

First, the Pyrogel is probably the best insulation you can buy. Cost me $150 and I could almost do two cars including the firewall. It comes in 5 and 10 mm sheets.

Second, stainless steel dissipates heat the slowest of the metals. In other words, of all the metals it could somewhat be said it acts as an insulator.

Third, the mirrored surface will reflect radiant heat.

I got the idea about Pyrogel from Kirkham's Billet build Cobra.

Picture of Kirkham's footbox with Pyrogel


Pyrogel


Here is a picture of my finished passenger footbox and firewall


This shows the firewall with the Pyrogel between a layer of .090" of aluminum and the .050" mirrored stainless steel on the engine side.


I realize this went beyond answering you question but I would try to use the mirrored stainless steel between the footbox and header. If you could then possibly use the 5 mm of Pyrogel or maintain an air space between the stainless using washers or nuts as standoffs.

If you have room inside the footbox you could cut a hole where the heat is getting to and rivet a sandwich, such as mine, of the Pyrogel from the engine side of the footbox extending into the footbox.

Or you could push a small piece of Pyrogel in that small space letting it touch the header and footbox and see how that works. Possibly rivet it in place. As I'm thinking about this the header would probably wear through though.

If you are interested, I can send you, let's say a 6" x 6" sheet of the Pyrogel to work with if you choose to go that way. PM me with your address. Be patient as I'm not on here every day.

Two last comments about Pyrogel.

It does not take up water.

It is a bit dusty and feels real funky working with it. I use Nitrile gloves and it easily washes off tools with Fantastic or plain water.

George

[mickmate]

Hey George, I like the look of Pyrogel. Where do you get it?

[dallas_]

Kevin,
If you want to do a simple aluminum heat shield here is a pic of one.
It's on an aluminum footbox but I would think you could do the same thing on a fiberglass one. These have a 3/16" gap between the shield and footbox so they don't take up much room.

[GWL]

Nick,

Goggle Aspen Aerogels for the manufacturer and different product information. The manufacturer only sells in large quantities, so I found a distributor in Pawtucket, RI. I do have another distributor in my files but this is the one that I ended up using.

Airtight Distribution
435 Narragansett Park Dr.
Pawtucket, RI 02861
Phone: 401-499-8813

There are other choices for insulation but the product I used is Pyrogel XT and is the better one for my situation with the highest insulating properties.

George

[KevinW]

Originally Posted by dallas_

Kevin,
If you want to do a simple aluminum heat shield here is a pic of one.
It's on an aluminum footbox but I would think you could do the same thing on a fiberglass one. These have a 3/16" gap between the shield and footbox so they don't take up much room.

nice - but on one side i only have 6-7 mm, so only leaves me about 2 mm air gap between header and heat shield.

much appreciate all the posts tho' - food for thought.