Heat Management / Header Wrap (also for your turbo guys)

[PDenbigh]

I'm looking for facts and opinions on heat management techniques for exhaust systems. I have a turbo car that generates a notable amount of heat among the header, turbo, external wastegate, and 3" downpipe. I have had all of the components Jet Hot coated, and that decreased the levels of under hood heat by a notable amount but after 30 minutes on track it's toasty.

I would like to do something additional to the downpipe. It is 3" in diameter and about 2' of it is in the engine bay. As such, it provides a lot of surface area to dissipate heat into the engine bay.

My current idea is to wrap it with some header wrap. I have heard that this method causes the metal to deteriorate from the inside out, and other times it just casus cracks.

Anyone able to shed some light on this? From experience or otherwise?

Thanks a bunch!

[HAULN-SS]

Ive also heard it speeds deterioration..and also it looks like ass

[ScottyB]

i have heard of wrap causing moisture to be trapped between the wrap and the metal, but i do not know under what circumstance that happens. it may also be a factor of poor material choice for the pipe or poor quality wrap....i don't know.

what about a heat shield? although its not fresh in my memory it seemed like your engine bay had a good deal of space to work with. maybe weld up some brackets and put a nice 1/16 thick piece of aluminum in there? maybe one between the turbo/DP and engine head, and have it sit so that it seals with the hood to create a realitively airtight barrier at the top.

i also recall old sierras and cosworths having those oval shaped hood vents, one per side. maybe placing one above the turbo will help.

[.RJ]

i have heard of wrap causing moisture to be trapped between the wrap and the metal

At 1000+ deg, how long is that moisture going to last?

[HAULN-SS]

I dont know if you car has one or not, but an underhood insulator is thebest way to get rid of heat. I ordered one from Carmotorsports.com for my SS, and it seriously dropped the underhood temperature 50 - 100 degrees. I dont know what you'd have to do to get one made for your car, because whatever material they use is tough as shit, you cant even cut it

[JustinG]

ok consider this.....the instructions for header wrap tell you to soak it in water and then put it on the piping, moisture isnt going to last long with 1000+ degree temperatures. Although i used Stainless and normal exhaust tubing for my setup, the wrap supposedly causes the metal to deteriorate faster. How much faster i dunno but if it does within the cars lifetime while under the hood and being exposed to minimum moisture i have bigger problems than header wrap. I wrapped my DP with header wrap. i dont know of a heat difference because i havent driven the car without it I also have a heat blanket on my starter. But i am planning on getting a turbo blanket as well as attempting to wrap my manifold with the wrap as well. Well see how they do, i am not keen on the idea of my ECU being less than a foot away from my turbo and manifold. If you have the time though i would fab up a actual heat sheild, i cant really do this because of the location it would be to complicated and would force more hot air down onto the starter.

[Andy]

I've also heard the same junk everyone else has said. Header wrap works really well except for street driven cars because it does hold in too much heat.

Have you researched Swain Coatings. Their exhaust coating is suppose to be a lot better than jet hot. They advertise that with their coating, headers are warm to the touch even after 30 minutes of idling.

[ScottyB]

i have heard of wrap causing moisture to be trapped between the wrap and the metal

At 1000+ deg, how long is that moisture going to last?

ha, not while it's running you crazy cracka, i meant when the car sits all night, moisture could get into the wrap and speed up deterioration, or something.

[D_Eclipse9916]

Heat wrap reduces underhood temperatures. But where does that heat go? IT stays withint the heat wrap meaning your metal sees skyrocketing temperatures. Think how much heat dissipates within 1-inch of ambient air? Hundreds of degrees. Now you got something that keeps all that heat in with no place to dissipate, now the temperatures are not dissipating at all, your keeping that heat in. Basically almost the temperatures of combustion, as it has not dissipated any heat. Metal weakens at high temperatures so it would all depend on how good your metal was.

[.RJ]

But where does that heat go?

Out the tailpipe

[Evan]

Heat wrap reduces underhood temperatures. But where does that heat go? IT stays withint the heat wrap meaning your metal sees skyrocketing temperatures. Think how much heat dissipates within 1-inch of ambient air? Hundreds of degrees. Now you got something that keeps all that heat in with no place to dissipate, now the temperatures are not dissipating at all, your keeping that heat in. Basically almost the temperatures of combustion, as it has not dissipated any heat. Metal weakens at high temperatures so it would all depend on how good your metal was.

keeping the heat in the pipe is what you want. higher exhaust temps = higher exhaust velocity. Im surprised you didnt know that, being a turbo guy.

[white_2kgt]

Pete, when you come up you can see how much lower the temps were on my tail pipes where I wrapped w/ header wrap vs left open. All the paint melted off the unwrapped areas and the wrapped areas look brand new. Had I not tore it off when I backed out of the trailer it'd still be on there.

If you order some can I get you to pick me up a roll or 2 and I'll pay you back?

[D_Eclipse9916]

Yes, but too much heat will degrade the metal. Off course you want velocity, but then why would people upgrade their exhausts? Because it is a compromise between velocity and how much air can actually get out. Too big and you lose velocity, too small and you get too much pressure.

Keeping in heat is technically what you want, but you also would need good metal. As I said, metal would weaken, but IT ALL depends on how good your metal was......

Last sentence of my last post....

[ScottyB]

so are there any detrimental problems to using heat wrap? everyone has noted the merits of using it but does that mean its faultless?

[HAULN-SS]

It looks like ass ;x but I already said that

[white_2kgt]

It looks like ass ;x but I already said that

I don't see how it looks any worse than rusty old ass looking pipes, w/ the kind of heat generated by a turbo car or a big v8 ANY paint is going to melt off and all jet hot is going to do is flake and make a big mess. The drawback I see is the clamps needed to keep the wrap in place, they hand down low and catch on my trailer

[HAULN-SS]

Ceramic coating....most header manufacturers have pretty good warranty against rusting these days...for the coated ones that is

[white_2kgt]

Ceramic coating....most header manufacturers have pretty good warranty against rusting these days...for the coated ones that is

I've not see a single coating on a racecar that didn't melt right off, it just can't take the temps!

[JustinG]

they makew high temp silicone sprays in silver and black to spray over the wrap to seal it as well as give you the bling. They sell the wrap at advanced, but not the silicone spray. Plus i dont think it looks that bad, rather the wrap then rust.

[PDenbigh]

Thanks for all of your replys guys!

Since my car is strictly a race car now, and will only be driven at the track, I think I'm going to wrap some stuff up.

The problem with a heat sheild is that it will reflect some of the radiant heat, but it still just adds surface area to dissapate heat into the engine bay.

I don't want to insulate the hood b/c I want the heat out of there...

I think header wrap looks fine, looks "serious" and I see many race cars with it...

With a turbo you want as much pipe as possible. The turbo gives the ample back pressure. Soon I'll just have a pipe coming out under the passanger door ;-).

The highest temps your system sees is while cruizing on the interstate at 3k rpm because that is the leanest your engine goes (For fuel economy purposes). While on track, I get EGT's of between 1000-1300, while on the interstate they get higher than 1350.

Thanks for all the chat, good to know other points of view and provoke thought!

Pete