yes, it ruins the header

 

this is a very good information read...you can learn something for free..



Century Performance Center, Inc. :: Exhaust Header Heat Wraps - DO NOT USE


Why Header Wraps Suck ...

Why Thermal Ceramic Coatings are Recommended


Regularly we are asked about, or have commented on the use of header wraps (header tape). This issue is a real pet peeve of mine. Good or bad about a product I'll give my opinion based upon direct use and fact, and this stuff screams "Do Not Use!"



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.

BACKGROUND INFORMATION:



In the past, almost all NASCAR and other racing engine builders and crew chiefs used header wraps for the added power gains and thermal control benefits offered by their use. Problems occurred when these same teams had to replace the headers after each race (NASCAR) due to the wrap being about the only thing holding each header together. Most engine builders, crew chiefs, and definitely header manufacturers do not promote the practice of installing these wraps directly on the headers any longer! They now utilize the thermal coatings that are chemically and electrically applied to the headers. Popular header coating services include Airborn, Jet Hot, HPC, and some header manufacturers now applying the coatings in-house.



Imagine having to replace a $1200.00+ set of headers after each race weekend! Few but the most financially well-off race teams can afford to do this. Also consider the downtime in remaking a custom set of headers. Most custom header makers do not have copies readily available.



I believe that the wraps are good to protect various 'items' from heat, but not to hold the heat in the header. For example: you can use the wrapping for the protection of fuel and oil lines, wiring, covering a starter motor, etc.



Cool air needs to be around the header, and insulating it with a wrap to hold exhaust heat in makes the header material temperatures near molten. When you wrap the header you trap the heat in the header, but also in the material that needs to breathe to dissipate heat for it's own survival.



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. TRUE! But, when the header is not allowed to cool so as to dissipate those extreme temperatures that the wrap is controlling, you have now developed a heat absorption that compares to thermal friction. This causes temperatures to continue to rise beyond the normal exhaust gas temperatures (EGT's) the header material was designed to withstand. This holds true as with most any insulation.



Try this experiment the next time you launder a load of bath towels and then dry them. Immediately pull them out of the dryer and just toss them in a snug pile on your bed. Now leave them there for a many hours, even a day, and then open them. You will find that there is still a considerable amount of heat left in the center towels. This heat, even though the outer towels and bed are normal room temperature have been able to contain their heat. This is a simple thermal insulation test, but compared to your headers you have an internal heat supply constantly coming from the engine when running. The heat on the outside portion of the header material is trapped between the wrap, and soon will begin to fatigue the header. This build-up of heat is amplified by the wrap. Towels do not need to breathe, your header material does.



The EGTs stay the same but the properties of the header material changes by amplifying the temperature due to the insulation. This action goes against normal laws of thermal dynamics, but this effect is fact, and you have to pull the ears off most engineers before they believe you. This is the trouble with plenty of education, but NO "common sense"! Don't believe these statements, then go ahead and install the header tape on your headers ... we'll be happy to sell you a new header set!




HERE are a FEW TEMPERATURE READINGS TAKEN at DAYTONA MOTOR SPEEDWAY:



Below are the test parameters and results using Jet-Hot Coatings® coated and uncoated headers:

(10 Laps, same engine and car with identical headers, one standard, one Jet Hot® coated. Engine is ran between 6,900 and 7,500 RPM, and temperatures are measured immediately after the last lap with the engine idling at 2,000 RPM with identical sustained EGT's of 850º.)








MEASURED AT:


JET-HOT® COATED


NO COATING


DIFFERENCE




1" from engine


300º


750º


- 450º




2" above header port (on header)


210º


300º


- 90º




1" above floor pan (in car)


115º


165º


- 50º




Pretty impressive difference, and with any of these coatings you should take care to not damage the headers. The thermal coating becomes part of the header material. Most of the other coating brands are comparable to these figures (if they are multi-layer, inside and outside of tube applied using proper materials).


Read more: header wrap.... - *********** - #1 SXS/UTV Informational Forum

 

Thanks for the quick reply. I guess it's a heat shield project now.

 

holy header wrap King that was usefull infro mation ! good reading ,,i was just about to wrap them headers too! so now what? UTV INC heat shield and some hole patching under the seats and shifter wow does it get hot in there going 50 !

 

Thats was a verry usefull and informative responce there thanks for that education. I learned something new today thats for shure.

 

KOTH,
I know you have some experience with this but to be the contrarian...
Most of us use our cars for rec use. Rarely even hitting the limiter.
I use a fiberglass type wrap that does breath some.
I do agree that a constant wet environment is no bueno.
Ceramic coating is the best- I do agree.
Wrap for a stock unit would be fine I feel. (unless you are bouncing off the limiter at rock crawling speeds all day)

I would rather see a conforming carbon fiber shield around the pipes. They work great on my bikes and I can grab the shield at full hot. They also allow some breathing room.

I have an an "S' so my issue is different. I get a lot of airflow to the header.
I am aware of the XP and its header routing.
The only real issue with the motor layout IMO.

 

I recently wrapped my exhaust with header wrap and can see a significant temp drop in the bed of my RZR. I don't have any engine mods and don't expect to therefore anticipate no problems with the wrapped exhaust. I ride for enjoyment and rarely hit the limiter, but IF I experience and exhaust failure I will post it here and will also have an excuse to install the only mod I might do with a aftermarket exhaust.

 

I just had my header, exhaust and heat shields ceramic coated.
They did the inside and out. My dealer is great, I had my rig in for a clutch adjustment and I asked if they would take off the exhaust system.
Ryan at the dealer told me he did not want to push my rig around the shop so he gave me a brand new take off system to have coated.
Then they kept my old one when they did the swap out.
Based on the un scientific test with a heat gun it drop the header temp over 200 degrees.
The coating is rated for 2000 degrees.

 

Man I like header wrap but now your making me think twice.

 

I tried lot of them on MCX turbo headers , but they really don't last to long even those extra high heat ones. On the end I just put ceramic coating and be over it. But, if I will be you I will still use the aluminum heat shield between the headers and bed even with exhaust wrap just to be safe. IMO
milos

 

My cheapo Pep Boys crap works well on a stocker bullet.
Even with hard and hot (90)running in Glamis.
Turbos are a different animal.

(I'm cheapo)

 

 

Has anyone tried the foil faced insulation board under the bed? I thought I might give that a try to reduce the heat transfer. If that doesn't do the trick, I've got an old aluminum road sign I'll put under there as a additional shield as well.

 

I have wrapped my mx quads after market exhaust's for years and not a failure yet. I just put on a new S&S on the Rzr and wrapped it to keep the heat off the bed. I plan to do a lot of creek and mud riding, so we will see if it holds up.