Heat shielding for underside of bonnet

GEEMCB · Post by **GEEMCB** » Sun May 28, 2006 6:29 pm

Hi, all

Since installing a heat shield between extractors & air intake, the bonnet has been getting very hot directly over the extractors. Not surprising - instead of dissapating across the whole engine bay the hot air can now only go straight up. (Obviously this only applies when the car is stationary after running for a while).

Anyone know of a source for reflective heat shield matting ? I've seen what looks to be aluminised flexible shielding on various turbo installations, but never thought to ask where to get it.

Ideas ?

Regards,

DBM58 · Post by **DBM58** » Sun May 28, 2006 6:41 pm

I do not know about its automotive application, but Forman Insulation on Vestey Drive. Mount Wellington offer a range of foam rubber type material with reflective foil on one side, self-adhesive on the other. It may be called Armaflex, or Formashield and is available in sheets of varying thicknesses.

Regards

Shermio · Post by **Shermio** » Sun May 28, 2006 6:46 pm

Im sure any performance car shops will be able to help you out...

if not then frab one yourself out of aluminium, not that hard and the material is usually really cheap (Free) if you go to metal shops and ask if they have off cuts...

Im assuming this is for the underside of the bonnet like a sandwich piece right? not a full blown heat shield for the engine.

GEEMCB · Post by **GEEMCB** » Sun May 28, 2006 8:08 pm

Thanks, David - will check it out.

Shermio - correct, just a sandwich-style arrangement.

Regards,

Okibi · Post by **Okibi** » Mon May 29, 2006 4:07 pm

Photos would help, but you could consider getting your headers ceramic coated, it really reduces underbonnet temps.

Info about bonnet heat shields can be read here on one of the Aussie forums.

SLYDIT · Post by **SLYDIT** » Tue May 30, 2006 4:45 pm

ALUMINIUM WONT WORK!!
IT needs to stainless steel to properly reject the radiated heat, aluminium has poor radiant heat rejection.(Hence the fact that your bonnet is hot)

I got my sheeting from..........................

REPCO.

Who'd av thought it!!!!

Shermio · Post by **Shermio** » Tue May 30, 2006 8:10 pm

Although I agree the poor radiant heat rejection, I will still think that Aluminium will work if set up as a sandwich style shield (i.e not actually touching the bonnet), this is because the air between the bonnet and the sheet of aluminium will act as insulation...

The main point of this exercise is to keep the engine heat off the bonnet, this set up using aluminium will do the job

and it's lighter than stainless.

Just my 2 cents

GEEMCB · Post by **GEEMCB** » Sun Jun 11, 2006 7:32 pm

All roads lead to Forman .....

I checked in with Don from Autoways who advised that he has used an insulation / cladding material for ducting that he gets from the business next door. He peels most of the fibreglass backing off leaving a sheet about 5mm thick of reflective foil with mat backing. He's fixed this with mechanical fasteners - these have a small plate that is stuck to the underside of the bonnet (or whatever) & a spike that pierces the insulation. A small clip holds the insulation in place. So that's one way ...

I did some more asking around & was referred (again - thanks David !

) to Forman in Vestey Drive. Talked to them & ended up getting a sheet of Formshield. It's got a quilted foil on top bonded to a 5mm foam backing. Non-adhesive & self-adhesive versions are available, both rated to 100C. I got the self-adhesive version. Comes in rolls 1m wide & costs $19.40/lineal metre + GST.

I cut a piece 500mm * 600mm & stuck it to the underside of the bonnet, effectively covering the underside of the bonnet bulge. No long-term data yet, but the adhesive stuck like pooh to a pig. Installation has resulted in dramatically reduced temperatures on the bonnet surface. I had thought that the hot air would simply spread out & heat the areas around the edge of the insulation - doesn't seem to be so. The whole bonnet stays quite cool.

So - there you go. The only tricky part was cutting a flap & leaving the backing paper in place so that the sticker under the middle of the bonnet can still be read (by anyone good with numbers & a working knowledge of Japanese ....).

The only other thing to be aware of is that Forman have several divisions - I dealt with the Building Systems people - apparently Forman Insulation is a separate outfit & who knows what goodies they have !

Regards,

Heat shielding for underside of bonnet

Heat shielding for underside of bonnet

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