Lets Talk Headers

[bimmertech]

i'm gonna stir the pot a little here. i was just measuring my header temps yesterday tracking down a misfire and found a good cylinder to be about 250 def F---i have bbk coated shorties.

i really don't think the coating will offer any performance gain whatsoever---unless it is a fuel injected motor with longtubes as the retained heat may help to keep the O2 sensors warm. it is there to increase life of the metal. i for one prefer the look of uncoated quality stainless steel.

 

[final5-0]

Looks like I found a subject with some interest

Containing the heat

As I understand it ... the benefit is not to promote cooler ambient temps
but ... keeping the heat in the tube to help scavenge the exhaust
pulses which is the main benefit of lt's over shortys.

Wrapping the header

I've seen it said that can promote premature failure due to the wrapping
holding in moisture. Just something I've seen on more than one occasion.

Hey Wes

Were you comparing the act temps between the two cars to determine
one ran cooler or what was the method?

Hey Robin

Were you using one of those temp guns you point and shoot to
determine the temps?

Intake pipe air temps

I got an engineer friend who works with that kind of stuff. He tells me
the air in the pipe won't be in there long enough to pick up ambient
engine bay temps. Basically ... the air is moving too fast to be effected.

Several asked about HTS coating

Is that not what comes on the MAC's
If it is ... I can say from my experience with them ..........
You can scrape it off when installing them

About the Jet Hot Coating

I'm with Keith about thinking it is a dip or something along those lines
cause I've seen some say the coating is on the inside as well

About a coating AND wrapping

I would have to do some research before I did that simply cause I
just ain't got a clue

Good discussion
I certainly don't got all the answers
but
I do wanna learn more

Some things I shared here were not confirmed but just stuff I've heard
so ... if anybody has better info ... please ... lets update it

Grady

 

[Pokageek]

Ok. So I would think heat wrapped (like a blanket) would insulate a LOT better than a simple coating.

MY PURPOSE is not for HP though. I am mainly thinking of keeping the nasty heat off all my accessories , hood and plastic parts though..I can't find any factual comparisons yet though.

HP wise, probably the jet hot would win because the way it is prepared.

"my stock headers would read 575* and my ceramic coated LTs would
read 350* and that was taken at about 93* ambient temp"

So if bimmertech's are 250*, that 575 -350* seems waay out there. Any other data on this persons car? Does he work near a steel plant by chance?

 

[magnj]

Here is an interesting article I found through a quick google search: http://www.centuryperformance.com/heatwraps.asp

For the Lazy here are some of the key points.

"THE FACTS:

* Header wraps are designed to keep the heat in the header to improve scavenging of the cylinders. Keeping the heat in the header allows the exhaust speed to remain high. (the right idea)
* There are no header manufacturers that I know of that will warranty their headers if any header wraps are installed on their products.
* In most cases the header wrap damages the headers beyond repair. (I will explain below)
* If you run a lean mixture, you "may" see a slim performance gain using header wraps. A rich mixture may show slim to absolutely NO gain in performance.
* If you do not mind replacing your headers and header gaskets regularly, and you like that ugly look of a wrapped header, go ahead and use the heat wrap.

Under normal use and even more with higher EGTs and header surface temperatures, headers will oxidize and material is actually removed from the headers. This means they get lighter and weaker.

Heat wraps are great, just do not use them ON the header. Use them on a device or component on your vehicle that you are trying to protect from header heat."

Also a thread on SCCAForums that contains first hand accounts: http://sccaforums.com/forums/thread/205167.aspx

And another discussion on a BMW Forum: http://forums.bimmerforums.com/forum/showthread.php?t=555439&referrerid=56200
Remember that the wrapped metal cannot cool properly and the header wrap is causing the material to super-heat and pre-maturely fail!

 

[Pokageek]

Interesting. BTW call us on it if we are getting too off topic.

FACT: I have had my headers on for 2 years - wrapped. They are cheap flowtechs (holley) and show absolutely 0 signs of compromise. I think it will keep the temps down which is a good thing.. and less expensive than coating.

HOWEVER, I WILL be coating those headers (INSIDE AND OUT) with the "suggested" parts in my link to the wrap (after reading this thread) to protect them. So if my flowtech headers have easily lasted me 2 years, it would make sense that the more expensive hooker swaps last longer especially when coating them with protectant inside and out... So if they only last me 4 years, I could care less. That will be 2011.

"Header wraps are designed to keep the heat in the header to improve scavenging of the cylinders. Keeping the heat in the header allows the exhaust speed to remain high. (the right idea)"

QUESTION: What good is an idea if it don't work? (For y'all HP freaks) Is this where Jet Hot comes in?

"Heat wraps are great, just do not use them ON the header. Use them on a device or component on your vehicle that you are trying to protect from header heat.""

This makes ALOT of sense. HOWEVER I don't want no heat wrap under my cowl hood so it goes on ----> the headers.

I am still going to look into more factual data on the difference in coating vs wrap as well...

HEY I FORGOT - cats made my underhood temps go WAAAAAAAAYYYY up! Very very noticeable when opening the hood.

 

[urban96]

i think i read somewhere that people who wrapped their headers had problems with them rusting out quickly. The wrap was holding in moisture

 

[94v6GT]

Here is an interesting article I found through a quick google search: http://www.centuryperformance.com/heatwraps.asp

For the Lazy here are some of the key points.

"THE FACTS:

* Header wraps are designed to keep the heat in the header to improve scavenging of the cylinders. Keeping the heat in the header allows the exhaust speed to remain high. (the right idea)
* There are no header manufacturers that I know of that will warranty their headers if any header wraps are installed on their products.
* In most cases the header wrap damages the headers beyond repair. (I will explain below)
* If you run a lean mixture, you "may" see a slim performance gain using header wraps. A rich mixture may show slim to absolutely NO gain in performance.
* If you do not mind replacing your headers and header gaskets regularly, and you like that ugly look of a wrapped header, go ahead and use the heat wrap.

Under normal use and even more with higher EGTs and header surface temperatures, headers will oxidize and material is actually removed from the headers. This means they get lighter and weaker.

Heat wraps are great, just do not use them ON the header. Use them on a device or component on your vehicle that you are trying to protect from header heat."

Also a thread on SCCAForums that contains first hand accounts: http://sccaforums.com/forums/thread/205167.aspx

And another discussion on a BMW Forum: http://forums.bimmerforums.com/forum/showthread.php?t=555439&referrerid=56200
Remember that the wrapped metal cannot cool properly and the header wrap is causing the material to super-heat and pre-maturely fail!

if hotter gas flows faster, i have to raise the question of whether or not the exhaust is in the header long enough for the heat to affect its behavior?
-the exhaust explodes out of the valve WAY faster than it enters the chamber.
im a lil bit doubtful of the temp of the primary tube having a significant effect on the exhaust gases for the fraction of a second that its flowing through the header

 

[final5-0]

I'm no header expert but I did study up on it a time or two in the past

First of all ... scavenging should only be thought about with LT's as
shortys just aren't long enough to benefit from that.

The collector is where it all takes place.

Grady

 

[Pokageek]

[EDIT] These are my observations.. I could be wrong..but here goes, thanks to Grady for creating this thread, I am writing a freaking term-paper :


#1 The 375 -575* temps VS. bimmertech's 250*disparity:

I am going to guess the hotter car had CATS OR a poweradder. Open up yer hood with cats and without cats is the difference between sweating and not. It is THAT big a difference. I have had turbo cars too. SOO hot under there, it will sinch yer eyebrows off within 2 feet!!!

#2 "wrapped metal cannot cool properly and the header wrap is causing the material to super-heat and pre-maturely fail!"

FIRST, thanks for the links - some good info on them and some bad.

The BAD, far as I can tell...neither forum thread has any significant factual data on the failing of wrapped headers.. (not downing it, just observing) but a lot of opinion and internet hearsay, unless I missed something that seems to keep getting passed on.

The thread for company selling coated headers are calling themselves "experts" (they might be i dunno)and saying all kinds of stuff with nice charts (on heat and flow and stuff) but no real evidence of headers consistently going bad with wrap other than their word (may be true just no data). The only consistent facts I found were "Engineers, Metallurgists, and other experts out there will state that there is no way that the material can fail because it can withstand, and it was designed to withstand, the internal temperatures of exhaust gases." see more under "notes"

The Good, The guy with personal experience who's headers lasted 4 years said he PREPPED them and had no issues. Coat them, wrap them, idle them (30 minutes) and coat them again with the can of .."stuff." and no problemos..

Conclusions

* Prep the headers and wrap them if you want to save money, keep bay temps down and perhaps get a performance gain (no factual data on perf gain that I can find).

* NO prep on headers and wrap ? = me personally? my headers still going strong after 2 years and they are cheapos although this would be taking a chance according to "the internet".

* High temps from cats will most likely CONTRIBUTE to deterioration of WRAPPED headers and huge increase in bay temps.


Notes: I looked at both threads and the consensus for wrap seems to be for lowering underhood temps NOT performance. Athough "prematurely fail" is a strong statement, ONE guy mentioned he bought cheap headers that went bad around one weld but that was most likely b/c he did something not the heat wrap. He goes on to say his cheapo headers lasted 4 years with wrap aside from the bad weld. Aside from the site link selling coated headers..EVEN though several people state "heat wrap kills headers" None of them have personal experience with it... unless I missed someone.

"Mild Steel (1010) uncoated header exposed to 1200º F. in normal air will have a weight loss percentage of roughly 25%with only 10 hours use at this temperature" I smell marketing gimmick here..My headers weigh 10# for example and they are saying they will weigh 7.5# in 10 hours?? .. what is their definition 1010 mild steel? trash can weight ? It can be MANY different thicknesses I believe.. what other factors? sounds way fishy..

 

[SeventyMach1]

Wait! We left out chrome plated headers!


J/K.


On the header wrap ....

On first thought .... I thought of it like Pokageek's first comment ... on how you would think a wrap would be better. On 2nd thought, I understand all the things being said in magnj's post. I would never use it. My question is ... why do alot of the big wig drag racer's still use wraps alot? Cuz they are old & senile?



BTW, not only jet hot headers, but also ceramic headers are often coated inside and out.


Another interesting coating. Ti-tech headers. They are titanium coated. Not only are they heat resistant, but they are supposed to prolong the life of the headers. How well would these keep heat inside?

 

[Therian]

The sad thing is, we'll never get any sort of dyno comparisons on this, simply because the only way to accurately measure would be to use the exact same car...and LTs are such a PITA to get out and back in, I couldn't think of anyone crazy enough to do such a comparison/test.

 

[final5-0]

[EDIT] These are my observations.. I could be wrong..but here goes, thanks to Grady for creating this thread, I am writing a freaking term-paper

#1 The 375 -575* temps VS. bimmertech's 250*disparity:

#2 "wrapped metal cannot cool properly and the header wrap is causing the material to super-heat and pre-maturely fail!"

Well ... I did think this would be a good discussion
and
It looks like it is at least making peeps think a bit out of the box

I've looked at the wrap issue before and like you ......
I could not come to a conclusion that made me feel total pro or con

On the header wrap ....

On first thought .... I thought of it like Pokageek's first comment ... on how you would think a wrap would be better. On 2nd thought, I understand all the things being said in magnj's post. I would never use it. My question is ... why do alot of the big wig drag racer's still use wraps alot? Cuz they are old & senile?

Hey ... Be careful about using that senile word :Zip2:
Its quite peaceful when you slip into that little world

A dedicated race car can do things a street car can not
and
Here is a perfect example

Lets just suppose that wrap does in fact cause failure in half the time
Who cares ...
For the short amount of time the car is in use ... That is a long time
and
Those big time racers get their headers GIVEN to them

The sad thing is, we'll never get any sort of dyno comparisons on this, simply because the only way to accurately measure would be to use the exact same car...and LTs are such a PITA to get out and back in, I couldn't think of anyone crazy enough to do such a comparison/test.

Yes ... that would be tough to do on a Stang and Dynojet
but
On an engine dyno it would be cake

I have data that shows LT's do have a tendency to promote
better low/mid range torque than shortys

I don't have my header categories broken down to much more than ...
LT's or Shortys
OTS or Custom
Size

I'm gonna start including coating
Over time ... the data will tell all
cause
The data ... It is not subject to opinion, bias, or hear say

Good discussion my friends

Grady

 

[Bosko5.0]

Grady I was using a temp gun about an inch back from the header flange.

dont they make header wrap sealant that stuff in a can.

 

[final5-0]

Grady I was using a temp gun about an inch back from the header flange.

dont they make header wrap sealant that stuff in a can.

I don't know about that

I honestly could care less about the temp in the engine bay

Of course ... I don't want temps so high things get damaged
but
Unless you idle for extended periods ... that should not be a problem

For the typical Car NA Street Car .......
Coated, uncoated, or wrapped ... I can't imagine it is really gonna
make a difference with damaging things under the hood

Now ... When you utilize a pa ... things get different :Word:

As for performance ... it goes without saying ...........
If you source air from outside the engine bay ......
The temp should not effect things

The data supplied above shows containing the heat helps in the
efficiency of drawing out the exhaust pulses
That can only mean more power ... how much more ... who knows

Grady

 

[Pokageek]

Grady I was using a temp gun about an inch back from the header flange.

dont they make header wrap sealant that stuff in a can.

I posted this answer earlier..

 

[magnj]

I am by no means an expert, I'm just adding information I found on the net to try to help in this discussion

 

[WHITE94COBRA]

Ah hah my canadian friend, aside from them being shorties, I just happened to install JBA titanium headers a week or so ago, I took off bbk chrome shorties and I had it dyno'd with them on, I will be getting redyno'd in two weeks, I have changed nothing since the first dyno, (accept breaks, and I hallowed out the cats). But fret not, I also have a brand spanking new bassani X pipe with cats that I will be installing before the dyno run, so my data will be exactly the same save for the headers..... I will keep everyone posted...... Ohh and on a side note, the heat from the headers during the dyno run went from 275* (idle) to 680* at WOT high rpm's. I did a heat test because I was testing a theory on a/f ratio and exhaust temps, Grady you would find that test kinda interesting.

And who says only canadians are crazy......

The sad thing is, we'll never get any sort of dyno comparisons on this, simply because the only way to accurately measure would be to use the exact same car...and LTs are such a PITA to get out and back in, I couldn't think of anyone crazy enough to do such a comparison/test.

 

[Pokageek]

I am by no means an expert, I'm just adding information I found on the net to try to help in this discussion

No not at all. You offered some excellent info that we could use to help with an excellent discussion. I was hoping you didnt think I was attacking in any way. I am very interested in the topic and pros and cons.

 

[lietuvis91]

well, here's some hard factual data:


http://www.flirthermography.com/media/2004-015-DeMonte-FINAL.pdf

 

[go-stang5.0]

Titanium coatings would act just like ceramics i would assume. Generally any metal tha is a good/bad conductor of electricity is equivalently a good/bad conductor of heat. (Eg. copper wires and copper radiators). I know titanium is a very bad conductor of electricity and so it must also not conduct heat well (like ceramics). Also, I know of many people who use titanium backing plates behind brake pads on rigid non-floating calipers which have drop in pads (such as the brembo cobra r calipers or stop tech's and ofcourse many others) to keep heat from the pads from transferring to the brake fluid via. the caliper pistons to reduce the chances of boiling fluid. THeres also airgaps in between there plate which reduce the heat transfer but I'm not gonna get into that. Anyways the Ti will work just like a ceramic in header applications. However i coulden't tell you which one is better. You would need to know the thickness of both coatings, the heat transfer coefficient of both materials and a few other things to know for sure. Ceramics tend to be very heavy and brittle so the Ti would be more durable But headers are not "normally" subjected to impacts so the brittleness doesnt matter. Also the coatings are so thin that the heavness of the ceramic doesnt matter either.

So in summary, i couldent tell you which one is better at holding in heat (I bet the ceramic formulas are a closely gaurded secret). But generally speaking Ti and ceramic accomplish the same job in this application.