Heat Shield?

[Nero]

Here is the problem. 100kW in light fibregalss car. Exhaust clears the engine bay side by 30-35mm. Engine is producing a LOT of heat and engine bay is 'sealed' away from rad i.e. has no natrural airflow. Side of engine bay has been lined by 2 layers of ali/glass HEI heat shield blanket and headers have been wrapped in thermotec wrap. On a warm day in traffic engine bay temp is 60-80C and the engine bay walls are also 60C (despite efforts so far). Air has been piped in from two high pressure zones and blow directly onto the exhaust. Temp when running at 100kph is 40-50C (depending on heat of the day). The fibreglass enginebay walls are structural! and at 60C lose 50% of their strength (plus smell). Slots have been cut in the bonnet to let heat out when standing in traffic and the heat is such that there is a heat 'haze' over the slots! Heat soak had melted a silicone engine mount...this has now been wrapped in two layers of blanket and the heat soak and thermal transfer through the steel of the engine mount had been reduced. Fibergalls bay wall temp unchanged.
Solution 1. Make radiant heat barrier/sheild using .8mm 5005 ali and encase headers. Problem is that heat sill needs to get out and that lots of heat now reflected into block.
Solution 2. use spare thermotec to make either a facing onto the ali to absorb some heat OR as a packing between two sheets of 1202 .5mm ali, pop riveted together to make a heat shield.
Solution 3. make air dam (reduce GC to 70mm in process) and blow air into engine bay (may also duct amounts of water)
Solution 4. all the above!

Has anyone got any ideas or solutions? I cannot sprint this without this being fixed.

[Sockz]

I dont know much about the fibreglass, or anything for that matter... But i'd say enough with the heatshielding because it hasnt done much for you up to this point.

Try and get some positive airflow to the engine...

Have any pictures of the engine/front of the car?

[Warpspeed]

Hmmmm.

Directing cooling air directly at the headers is probably not the best way to go. This then becomes hot air that just spreads the heat further. I would be ducting the high pressure cold air at whatever I wanted to protect.

Perhaps encasing the headers, and extracting the superheated air from this zone, so the hottest part is the last thing in the engine airflow path, not the first.

I think you are going to have to force more air circulation through the engine bay, perhaps with an electric fan, and remove the heat, rather than trying to reflect it with shiny surfaces.

[sr20dat]

ive heard of people using boat bilge blowers try http://www.whitworths.com.au

[dattoman1000]

Remove the thremolec tape and have the headers HPC coated with the special marine high temp stuff. This will cut temps down and reduce damage to the headers. They tend to destroy themselves over time with the tape. Have them coated inside and out.
Small extractor fans can be fitted to remove temp from the engine bay controlled by a thero switch to only operate when required. This is a common thing with 240+260z with Chevs in them to reduce underbonnet temps.

[Nero]

Airflow is proving a problem at the moment. I have done tuft tests and have a high pressure on the top of the bonnet relative to under the car. So the slots in the bonnet actually take in air, which then goes down the tunnel/under the car. As high speed lift is a problem I don't really want to duct a lot of air from the top to the bottom (I think the bottom, there are not many places it can go). The second problem is where to get the air from. I can duct under the car, but cannot just cut more holes as with fibreglass monocoque, the engine bay panels are structural.At this point I am thinking that the engine bay temp is not so much the issue as the carb inatke/filters will be enclosed in the near future, but more the temp of the engine bay walls .
I had thought of the fan, but do not really have any room. I could run a naca duct from further front in the bonnet to get more air in, but will have to find where it goes!
Datto, the thermotec stays. HPC is good but too good for the headers I have. I will make a new set in 12mths or so and maybe HPC then. I am aware that the wrap will halve the life of my headers, but I don't like them much anyway (badly made by a ex shop)
Warpspeed, the heat shield 'chimney' idea is an interesting one and parallels one that I had with the shielding running up to the vent in the bonnet. I had thought of then ducting some air into this structure and then some behind it as well.
As a general rule I don't like the thermotec/HPC idea as it really just shifts the problem to another part of the car. The tail section of my ex is now much hotter than before, and it sits close to my 'tank..not a happy combination.
Will find a photo