Jay Wellwood

Sounds like the baking process may induce some distortion? Perhaps a jig of some sort would help minimize this effect.

Certainly seems to be less risk than using wraps - although that video of the blow torch testing posted by AZ is quite impressive! Still though, although the insulation material appears to be impervious, it would be the oil that catches fire. I've seen insulation pads on power plant turbine housings get oil in them only to erupt in flames...it makes for some excitement for a few minutes - and that's in a relatively open space. In an engine compartment I'm sure would be a whole different story.

Laust Pedersen

I have had various exhaust systems coated since early 90’s and still think it is a worthwhile process, but it is not a “miracle method” for thermal isolation. Our header shields with (almost) still air as the isolator are far better and worthwhile preserving as the picture in post #8. Since the bellow has very large surface I would wrap that short section (as I have on my 951).

Internal coating functionally is an even better solution, since it reduces the temperature of the pipe material, reducing thermal gradients and therefore also the probability for thermal stress cracks.
Even though the EGT can be higher than the rating of the coating, the exhaust gas has very little oxygen, which is what breaks down the coating at high temperatures, so it does last for as long as external coating.
An often mentioned concern is, that the coating could flake off and damage the turbine wheel, but in the 2x10 years I have used pre turbo charger coating (Jet Hot), that has not happened, nor have I seen any signs of internal coating flaking off.

I have my crossover pipe wrapped as well for years without fires in spite of a couple of cam tower gasket breaks, resulting in a lot of smoke only.
The disadvantage of thermal wrapping is its limited lifespan, which is maybe 3-5 years in my experience.

Laust

George D

I've used most of the available heat barrier materials on about every car I've owned, including 3 modified 951 cars. The first viable coating developer was Swain. I've used them with great success. The one issue I've always encountered, especially with our motors, is heat dissipation. Whether from the internals of the motor, (oil - water) to the intense heat produced externally (turbo - headers).

My tuner, Mario, also tunes/designs record holding salt flat twin turbo charged motors burning nitromethane with boost levels well beyond anything seen in a road going motor.They have large budgets, and will do anything towards heat reduction. Mario uses these folks for all their heat coating work. http://www.metzcon.com/affordable/

My engine bays in our cars are hotter than any turbo motor I've owned, but these cars seem to hold up much better than most running at these temps. Seeing up to 1800 EGT's in some cases, depending on the lean/part throttle running up hill mandates at least 321 stainless, and better yet, Inconel 625 in the header material. Don't worry, as soon as you put your foot in EGT's drop immediately, and we've richened up the part throttle maps.

The emitting thermal coatings on the boost/intake tubes are coated internally and externally with different coatings. The intercooler is only externally coated, intake is internally and externally coated but the outside uses a heat barrier ceramic coating, somewhat like what's on my headers. The headers are internally and externally coated with heat shielding material installed surrounding the headers. My hood is vented, and has a heat barrier material attached to the underside of the hood. The venting makes a huge difference, and having your intake reside out of the engine bay is, in my opinion, one of the first things to do when budgeting for your 951 project. It's fairly straightforward, and I've seen good results from this mod only.

Here are some pictures of my engine bay. Some are hard to see well, as it's kinda "stuffy" in there.

Hope this helps with the OP's post.

ehall

Just a question. because I have no idea about the answer, but is there any good use for the gold foil, like you see on race cars? If so, where?

Jay Wellwood

Thanks for sharing George. BTW, that is one cool looking intake.

ehall

George, do you have a quick good pic of your hood venting, form the outside? What is the agle on the venting, roughly?

George D

This film "reflects" heat, not absorb/dissipate. Think of the "space blanket" you'll find in all decent survival kits.

This material is very good for rejecting heat transmitted into the "drivers" seat, cockpit, wiring, firewall, undercarriage above the exhaust, etc.. There must be an air gap between the material and source you're trying to protect, whether an occupant, wiring, firewall, etc. Without this air gap, it's not nearly as efficient, and a waste of time-money. The factory 951 headers have this air gap between the shield and actual header. They didn't do this to save money.

I'm sure there are other uses, but "safety" of the occupant/driver is the highest and best use I'm privy. There are much better materials to stop the transmission of heat without reflecting it back to the source.

George D

Here's a few pictures of the hood vents and air space within the heat shielding material used under my hood, above the exhaust, on wiring, etc.

ehall

Okay, so those vents are pretty much the standard that I expected. As for the gold wrap, I've seen it used on numerous surfaces, most of which appear to be intake manifolds, on IMSA DP class cars, and many others, including Brumos' porsches, when they ran GT. none of those looked like they had a barrier between the material and component they looked to protect.

333pg333

I've seen visible heat haze billowing out of those same vents when back into the pits. I'm sure they do a bit while moving but could be quite a lot more aggressively made for more effectiveness when at speed. Still, far better than nothing in my opinion. We still have the same vents as George. Will get around to modifying or changing them oneday.

George D

Depends on what you are applying the reflective material towards heat rejection. Here's a good site towards the differences: http://www.formula1-dictionary.net/heat_shielding.html

Jay Wellwood

Thanks for the link - good stuff.

jerome951

Is this for street or track use?
If street, why not just either put a manual switch on your low-speed rad fan, or integrate a separate temp sensor which measures underhood air temps instead of coolant temp?

DanaT

Are those vent from the Swiss guys?

George D

Rad fan lower temp switch: done on all these cars. Under Hood temps don't matter, only my oil/H20 temps have my attention. All's good here in HOT Tucson, AZ in my 951. Cold AC, decent stereo, and track ready once I'm willing to deal without AC.

G