I personally think it's a line of BS, but last night I was showing my setup to a friend and some people that I just met. Well one of the guys said that the wrap will eventually cause the header to rust out because it traps moisture in between the wrap and the header causeing it to rust out "without me even knowing it". I have a DC ceramic header and I can't even imagine this being possible. I argued with him about it for a while but just dopped it to shut him up. I even told him I don't drive it in the winter but he said that didn't matter.

I want to know your opinion, has this ever happened to you or have you seen this happen? Like I said, I think it's BS and this guy is an idiot.

 

It can make the header more prone to cracking since the header itself will get a bit hotter due to the trapped heat.

 

Do a search, this comes up every week, but yes it causes problems - even if using 321 SS or Inconel. While it has something to do with trapping moisture, it doesn't cause rusting, but thermal stresses. Believe me, I'd like to use it, but people I know who worked on factory race cars said it's a bad idea. Even using wrap on aviation headers made of inconel causes trouble, so it's not just race cars.

And yeah, I know some people have used it for years with no problems, I'm just passing on what experts say. FWIW, I don't know of any header maker who'll cover cracking if the header was wrapped. What's that tell you?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by omahaturbocivic &raquo;</TD></TR><TR><TD CLASS="quote">It can make the header more prone to cracking since the header itself will get a bit hotter due to the trapped heat.</TD></TR></TABLE>
This is exactlt right . Header wrap is the best thing you can do for performance for the DC header, but the higher heat subjected to the header is more than they were made to operate at. So it will make them more prone to crack. Rust? I'm not sure. Anything is possible i guess. The Hot Rod instuctor at my school thinks DC and GReddy headers are Sh*t(I don't agree)But said if you wrap them you will get far better results. He really hates hondas and anything related though.

 

Well this guy was talking about the header rusting out and not cracking. I did research a lot before deciding to wrap the header and I did understand the risks associated with it.

My question was about the wrap causing rust.

Anyway, I've had the header for 2 years now with no problems and the benefit of the wrap out weighs the "possibility" of the header cracking. Underhood temps are super low and you can touch the header with your bare hand with the car running and you won't get burned. I love the stuff.

 

think of it this way... would you wrap a blanket around an oven? That's essentially what you're doing when you wrap your header. I think this is the dumbest idea they ever came up with when they came up with this crapola.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hybrid Invasion &raquo;</TD></TR><TR><TD CLASS="quote">think of it this way... would you wrap a blanket around an oven? That's essentially what you're doing when you wrap your header. I think this is the dumbest idea they ever came up with when they came up with this crapola. </TD></TR></TABLE>
It comes down to what your more worried about. The stuff does work very well. I wrapped my downpipe because it was very close to my radiator and it caused the car to over heat. Before i would not let my hand get near the area of the downpipe after the car had been running a while, now you can touch the actual downpipe while the car is running and the area is very cool. I know my downpipe may not like it but im more worried about all the stuff around it. For my situation I feel its an excelent product and it does its job well, the benefits definately outway the risks.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hybrid Invasion &raquo;</TD></TR><TR><TD CLASS="quote">think of it this way... would you wrap a blanket around an oven? That's essentially what you're doing when you wrap your header. I think this is the dumbest idea they ever came up with when they came up with this crapola. </TD></TR></TABLE>

MMMM.... good post, I see you've done your homework.

Wrapping the header is suppose to do 2 things:

1. Reduce underhood temps and parts near the header like omahaturbocivic did with his downpipe.

2. Theory states if you can keep the exhaust gas as hot as possible and stable, it will flow faster through the header, further increasing power.

Now that I had to educate you a bit please refer to the question. I was asking about wrap causing rust, not "should I wrap?" or "what is your off the cuff opinon on header wrap?". Some uneducated boob like yourself tried to act smarter than he really is thinking he was talking to some kid dumber than him. Being open minded, I would really like to see if he had any merit to what he was talking about. Now if you have seen this in person tell me about it, otherwise don't waste other people's time reading your posts.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Buzzbomb &raquo;</TD></TR><TR><TD CLASS="quote">

Now that I had to educate you a bit please refer to the question. I was asking about wrap causing rust, not "should I wrap?" or "what is your off the cuff opinon on header wrap?". Some uneducated boob like yourself tried to act smarter than he really is thinking he was talking to some kid dumber than him. Being open minded, I would really like to see if he had any merit to what he was talking about. Now if you have seen this in person tell me about it, otherwise don't waste other people's time reading your posts.</TD></TR></TABLE>Funny how I never asked(nor needed) you to "educate" me, as you put it.
Secondly, I voiced my opinion about how stupid I think it is(while knowing the purpose)of wrapping a header. I need not to prove that to you or anyone else, so seeing as how you can call me uneducated just reflects that you prefer to judge someone you don't know, rather than be civil when you're the one wanting help.
Do you feel better now that you've attempted to belittle someone based on your ability to share the fact that wrapping a header lowers engine compartment temperature? If that's something you assumed(once again) I didn't know, sorry to bust your bubble, chief. You site me for attempting to sound more intelligent than yourself, yet you're the only one insulting anyone here. It's funny how people site other people for shortcomings that they themself are actually guilty of...
Anyways, reverting back to the topic of the thread......

 

You make a fairly valid point and I'm not usually quick to insult people's posts, but the original two sentence post starting with "oven wrapping" and ending in "crapola" just sent me off. I don't know how many times I'll be talking to someone who voices an opinion on something that they have no idea about. Since you do know the purpose of wrapping and you think it's crap then that's cool, I respect that and apologize, I got the wrong impression from your first post.


I also am not a fan of getting into pissing contests on post boards so we'll just leave it at that then.


Modified by Buzzbomb at 12:24 AM 5/19/2003

 

fair enough, and I respect that. Thanks for not turning out to be a dick

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Buzzbomb &raquo;</TD></TR><TR><TD CLASS="quote">2. Theory states if you can keep the exhaust gas as hot as possible and stable, it will flow faster through the header, further increasing power.</TD></TR></TABLE>

Would you mind discussing why you want to keep exhaust gas as hot as possible? An increase in gas temperature obviously implies an increase in gas pressure and therefore (by Bernoulli's equation) implies a slower volumetric flow rate. High pressure also means more turbulent flow = slower than laminar flow (low pressure). Basically, heat and flow stability are inversely proportional, so I don't quite follow the "theory".

Please skip all the uneducated talk too. I am not being aggressive, here, I simply don't follow #2.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSpeedR &raquo;</TD></TR><TR><TD CLASS="quote">

Would you mind discussing why you want to keep exhaust gas as hot as possible? An increase in gas temperature obviously implies an increase in gas pressure and therefore (by Bernoulli's equation) implies a slower volumetric flow rate. High pressure also means more turbulent flow = slower than laminar flow (low pressure). Basically, heat and flow stability are inversely proportional, so I don't quite follow the "theory".

Please skip all the uneducated talk too. I am not being aggressive, here, I simply don't follow #2.
</TD></TR></TABLE>

I've read and i've seen lot's of race cars (WRC and such cars) that follow the same rule (that you want the exhaust gases hot), but now that you mention it, i been thinking about it, and i think the same as you.

Maybe someone can educate us.

BTW: thanks to the creator of the post and the other guy for being Nice people and not going at it. Very mature

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSpeedR &raquo;</TD></TR><TR><TD CLASS="quote">

Would you mind discussing why you want to keep exhaust gas as hot as possible? An increase in gas temperature obviously implies an increase in gas pressure and therefore (by Bernoulli's equation) implies a slower volumetric flow rate. High pressure also means more turbulent flow = slower than laminar flow (low pressure). Basically, heat and flow stability are inversely proportional, so I don't quite follow the "theory".

Please skip all the uneducated talk too. I am not being aggressive, here, I simply don't follow #2.
</TD></TR></TABLE>

I don't think you're aggressive at all, your theory does make sense.

I see your point, but from everything I've read, this is how I understand it:

It's not about the temperature of the exhaust itself; I shouldn’t have said keeping the exhaust as hot as possible because you're not increasing the tempurature, it’s more about keeping the exhaust the SAME temperature throughout the header. We all know about gas pulses that go through the exhaust system, and these pulses help evacuate the exhaust from the combustion chamber. From what I understand, as the exhaust goes through a header, there is much more area that is exposed to air than a manifold. The exhaust can cool down at a high and uneven rate, disrupting the pulses a bit. Now this isn’t going to cause adverse effects compared to a manifold, because the design of the header is superior, but wrapping the header is suppose to keep the temperature of the exhaust the same to keep more flow through the header.

That was my understanding, you're not increasing the temp, just preventing uneven cooling. You have 4 pipes coming out and each could cool the exhaust more than the other. Does this make any sense or does it sound like crap? I'll do some more research and see what I find.

 

i have my header wrapped. it's ceramic and it has not rotted away and it's about 3 years old now.

also my previous header was also wraped and it was plain old mild steel and it had some minor surface rust because it was just steel but it was in no way connected with the header wrap.

if i had to get another header i would deffinatly wrap it again.........it really helps keep the heat out of the engine compartment!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Buzzbomb &raquo;</TD></TR><TR><TD CLASS="quote">

I don't think you're aggressive at all, your theory does make sense.

I see your point, but from everything I've read, this is how I understand it:

It's not about the temperature of the exhaust itself; I shouldn’t have said keeping the exhaust as hot as possible because you're not increasing the tempurature, it’s more about keeping the exhaust the SAME temperature throughout the header. We all know about gas pulses that go through the exhaust system, and these pulses help evacuate the exhaust from the combustion chamber. From what I understand, as the exhaust goes through a header, there is much more area that is exposed to air than a manifold. The exhaust can cool down at a high and uneven rate, disrupting the pulses a bit. Now this isn’t going to cause adverse effects compared to a manifold, because the design of the header is superior, but wrapping the header is suppose to keep the temperature of the exhaust the same to keep more flow through the header.

That was my understanding, you're not increasing the temp, just preventing uneven cooling. You have 4 pipes coming out and each could cool the exhaust more than the other. Does this make any sense or does it sound like crap? I'll do some more research and see what I find.
</TD></TR></TABLE>

Alright, totally over my head on this one, but I just wanted to ask.

In essence you are saying that slight temp. changes within the header can disrupt flow? Would this also apply to the exhaust gases flowing throughout the entire exhaust system (all the way to the muffler)? Would keeping the temps even throughout provide more flow?

I apologize if this does not make sense or seems like dumb questions. As I said, the info in this thread is a bit beyond my grasp. I found it interesting though, and wanted to probe a bit more. Thanks.

 

GSpeedR:

I found this: http://www.nsxprime.com/FAQ/Mi...y.htm

The important part of the lengthy article was this:

"As discussed earlier, exhaust gas is hot. And we'd like to keep it hot throughout the exhaust system. Why? The answer is simple. Cold air is dense air, and dense air is heavy air. We don't want our engine to be pushing a heavy mass of exhaust gas out of the tailpipe. An extremely large exhaust pipe will cause a slow exhaust flow, which will in turn give the gas plenty of time to cool off en route. Overlarge piping will also allow our exhaust pulses to achieve a higher level of entropy, which will take all of our header tuning and throw it out the window, as pulses will not have the same tendency to line up as they would in a smaller pipe. Coating the entire exhaust system with an insulative material, such as header wrap or a ceramic thermal barrier coating reduces this effect somewhat, but unless you have lots of cash burning a hole in your pocket, is probably not worth the expense on a street driven car."

Hope that explains a little.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Buzzbomb &raquo;</TD></TR><TR><TD CLASS="quote"> Coating the entire exhaust system with an insulative material, such as header wrap or a ceramic thermal barrier coating reduces this effect somewhat, but unless you have lots of cash burning a hole in your pocket, is probably not worth the expense on a street driven car."

Hope that explains a little.</TD></TR></TABLE>

That is exactly what I was thinking of.

 

Hyprid Invasion, I even found some anti wrap stuff supporting your dislike:

http://www.centuryperformance.com/heatwraps.asp

Personally, I thought the article was a bit watery, but since my header is wrapped, I'll find out first hand either way!

 

I can understand that, but I'll probably do a bit of research on my own. Thanks for checking, though.

 

I wrapped mine. I never had a problem. I will continue to wrap everything hot under the hood from now on. My hood used to get so hot you could fry an egg on it. Now you can bump the header and not get burned. Cooler intake temps and less underhood heat = more power. Plain and simple.

 

sounds reasonable to me

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Buzzbomb &raquo;</TD></TR><TR><TD CLASS="quote">Hyprid Invasion, I even found some anti wrap stuff supporting your dislike:

http://www.centuryperformance.com/heatwraps.asp

Personally, I thought the article was a bit watery, but since my header is wrapped, I'll find out first hand either way! </TD></TR></TABLE>I like this atricle. Very good, thorough explanation of what wrapping does to a header.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSpeedR &raquo;</TD></TR><TR><TD CLASS="quote">Would you mind discussing why you want to keep exhaust gas as hot as possible? An increase in gas temperature obviously implies an increase in gas pressure and therefore (by Bernoulli's equation) implies a slower volumetric flow rate. High pressure also means more turbulent flow = slower than laminar flow (low pressure). Basically, heat and flow stability are inversely proportional, so I don't quite follow the "theory".

Please skip all the uneducated talk too. I am not being aggressive, here, I simply don't follow #2. </TD></TR></TABLE>
Increasing temperature doesn't inply an increase in pressure. That's the ideal gas state equation which doesn't mean anything here, because volume isn't held constant. Bernoulli's equation doesn't imply it either, and besides, its only strictly valid for incompressible flow. Actually, the pressure is almost the same, so higher temperature means lower density. This means higher velocity and higher volumetric flow rate.

I don't get what you're saying about pressure & turbulence. Higher pressure doesn't do much to the Reynolds number, since velocity & density are both linear in the numerator. Viscosity doesn't change much with pressure.

Higher temperature will drop the Reynolds number, but probably not enough to change flow regime to laminar.

But all that is for steady flow. It makes more sense when you're talking about flow through the cat-back piping. This thread is mostly talking about what's going on in the header. After all, nobody's talking about wrapping the exhaust pipe all the way to the rear bumper...

Exhaust 'flow' in the header is all about pulse reflection from different features in the header. That's non-steady, compressible flow. Bernoulli's equation, ideal gas state equation, and the other stuff from high-school physics don't describe what's going on here.

Oh yeah...
Wrapping ceramic headers so they stay hotter probably causes the ceramic coating to crack. Then the mild steel underneath the coating can corrode. So if you want to wrap them you probably should use stainless.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Buzzbomb &raquo;</TD></TR><TR><TD CLASS="quote">Cold air is dense air, and dense air is heavy air. We don't want our engine to be pushing a heavy mass of exhaust gas out of the tailpipe. An extremely large exhaust pipe will cause a slow exhaust flow, which will in turn give the gas plenty of time to cool off en route. Overlarge piping will also allow our exhaust pulses to achieve a higher level of entropy, which will take all of our header tuning and throw it out the window, as pulses will not have the same tendency to line up as they would in a smaller pipe.</TD></TR></TABLE>

That's the reason why having larger piping cause you to loose low end power and lots of people think that you need back pressure to run a car.