Exhaust wrap

[Bacchus]

Just a little suggestion for those guys going with aftermarket exhaust minus the power chamber.

exhaust header wrap. I went with a 4-1 exhaust system on my vmax, since I was going fo 'maxum performace I decided to put the exhaust header wrap, in black, on the bike up to the muffler.

was there any gain in performance.....Idunno... maybe
there was however some unanticipated additional benifits.

first she runs cool as a cucumber now. I guess it shoulda been an obvious benifit, I just diddnt think about that when deciding to go with the wrap. if you look at the way the exhaust runs, it essentially does a great job of cooking the oil while it sits in the oil pan.

One pipe on either side of the oil pan, hotter that the bjezuz, radiating heat into your oil. with the wrap the heat transmitted is a fraction of what it once was. you can go for a romp, getter nicn' hot, stop the bike and touch the pipes with your bare hand and dont get fried, very effective stuff at knocking down heat. Im sure heat radiated into the coolant is also a fraction of stock.

secondly, makes things look nicen' clean. Im sure this will work just as nicely with a zl9 and D&D system. really gives the bike the tucked up and tidy looks

http://i232.photobucket.com/albums/ee43/Bacchus1967/V%20MAXIMUS/101_1107.jpg

http://i232.photobucket.com/albums/ee43/Bacchus1967/V%20MAXIMUS/101_1103.jpg

[87kawzl]

You are limiting the life of your exhaust with header wrap.
It elevates the tube metal temp and the tube will scale away.
It doesn't take long to eat the metal away, be warned!

[kawboy]

You are limiting the life of your exhaust with header wrap.
It elevates the tube metal temp and the tube will scale away.
It doesn't take long to eat the metal away, be warned!

I've heard that, too. Just crumbles away to nothing.

[jmac]

You are limiting the life of your exhaust with header wrap.
It elevates the tube metal temp and the tube will scale away.
It doesn't take long to eat the metal away, be warned!


I've heard that, too. Just crumbles away to nothing.

As long as the pipe and the wrap stays dry.You should be fine.I have used that stuff on race car headers,and street car headers.Works great on the race car,but will junk a set of headers on a daily driver.The wrap will hold moisture,and realy speeds up rusting.If your not riding in the rain it should be fine.If they get wet be sure you run it long enough to dry completly.Just my thoughts,but I think you'll be fine.

[Blagadán]

:yeahthat:

What he said. I had an RG250 as a daily driver years ago. It had scratched up headers that didnt look pretty, but they were structurally sound. I put the header wrap on them to cover up the ugly. They looked trick and really cool, but within a year I was looking for new headers. They simply rotted away. I couldnt believe how fast they disintegrated. In the end the tape was the only thing holding them together. I was able to crush the header easily with my hand.

As was already said, keep them dry and you should be fine.

Nice look BTW Bacchus, I like!!

[WALTSTAR]

I like the info about keeping them dry, didnt know that. I did my zl1000 a few weeks ago for the new engine install. The only thing is i did the stock exhaust and the power chamber (i have thousands of feet of wrap from 1" to 4" wide). Take a look! Oh, the mufflers are just colored black as i took the picture before i sent them to jet hot...i am now painting the headlight bucket and rerouting some electric lines, but other than that, she's done.

[Bacchus]

are your headers wraped or painted?
Im assuming wraped, but its a little hard to be sure by the picture.

unfortunately the zl's dont have a temp guage the the vmax, so it will be difficult to tell if she runs generally cooler. I suppose that is a no brainer when you think of where the coolant, oil pan, and the header pipes are located.

I have also heard about pipes rusting with header wrap. I also belive that this is due to moisture rather than the heat. fortunately, I live in Phoenix, we dont have any moisture here, so unless you get them all wet when cleaning up the bike, youre pretty well guarenteed they wont get wet, besides I never ride in the rain.

when I installed the header wrap I also purchased and used a header wrap sealant. It's kinda like a high temp spray paint that seals up the materail so that it does not easily absorb moisture, it also brought the color out, darkend it up some and further helps to contain the heat, definately recomend using it. These pipes are also ceramic coated on the interior, should help to keep a good deal of the heat out of the metal.

[87kawzl]

I will say it again.
Increased metal temp causes the pipe to scale away, not rust.:nono:
Moisture has nothing to do with it.
ASME code allows A-36 to be used up to 700deg f because strength drops off a cliff at that point then at temps higher than that scaling will occur.

[lowlife]

If I may....try wrapping them the other way from the back to the front. That way the wind, rain, and daily strife will go with the flow of the bike not against it.
The butt dyno may not notice the power difference but its one of those..."enough little things add up"

I also wire tie mine or wrap it with wire. If you get small enough stainless wire it will hardly be noticeable. I have used wrap for many many years, they don't like rocks. A friend of mine said he wrapped it with electrical tape and it made it rock hard after melting....still not sure if I belive him or not.

Curious, My pipes run at 1200-1300 degrees at the outlet. So you are saying that is too high, as it is certainly over 700 degrees?
A properly tuned engine runs about 1250 or so as it exits the exhaust valve.This is measured inside the exhaust stream and can be confirmed with my infrared.

[lowlife]

Should also add that most of the pipes I wrap are Ti. But not all

[Bacchus]

lowlife.... good observation! I noticed that I when I installed them, would have been better to wrap in the opposite direction. the wrap is secured with high temp stainless straps, I painted them black to match the wrap and also secured with the spray on sealant. I also wraped them TIGHT TIGHT TIGHT. so far no problems.


87kawzl..... the headers are stainless steel while the head are aluminum, wouldnt the headers be more durable under heat than the head itself? the heat generated at the head where the valves are would have to be much higher..no?

what is A36?? maybe a stupid question but Idunno ....
I'm assuming that this is a grade of metal, I may be able to find out exactly what grade of metal is used in constructing this exhaust if you could use that information to determine the characturistics.

here's another thought, its not that the pipe is realy getting hotter, right at the bend as it leaves the motor those headers get hotter than the bjezus wether or not the wrap is in place, with the wrap on more of the pipe gets hot because the heat is not lost but transfered further down the line. the limiting factor is the exhaust gas temp ...no?
if lowlife is correct.. and the exhaust gas temp is well over 1000 degrees, the first bend of the headers would be well over 700 deg almost constantly...?
what abou the ceramic coating on the interior of the headers? does this not have an impact on the problems you've noted?

[WALTSTAR]

Answer to your question, these are wrapped up and i sprayed them liberally with high heat paint. The wrap itself is made by a industrial company for high temperature naval engine ehaust. I dont think rocks will hurt this stuff because you cant cut it with a razor blade... As far as scaling, i dont know...when the time comes that these pipes are shot, i'll just look for another set...

[87kawzl]

Grade 304 Stainless Steel will have a much higher metal temp limit say ~1000-1100deg f and should hold up to the wrap just fine. I thought the headers were carbon steel like the ZL's, sorry.

The aluminum heads are cooled (in our case liquid, air cooled has fins to maximize surface area). It is all about heat dissipation and insulating the outside surface dramatically increases the metal temperature. Aluminum absorbs and dissipates heat much more quickly than steel.

A-36 is mild steel (fenders,tank,frame,ZL headers) with none of the additives such as Chrome, Nickle, Ti... to give it good high temperature strength or corrosion resistance. I would not wrap stock ZL headers.

A good example of scaling would be brake drums/rotors if you have ever seen one that was stuck on or had the brakes on constantly, the material flakes away in sheets.

Ceramic coatings available can be applied inside and outside the tubes (several mil's thick) and works decent (still wouldn't touch the pipe). The ceramic fiber wrap is at least 1/16" thick and will offer much more insulation causing the tube wall temp to be much closer to the exhaust gas temp than the ambient air temp.

One note when dealing with the ceramic fiber wrap, it is just as bad for you as asbestos after it is heated over 1000deg. Wear a good mask when dealing with old used up wrap.

[killer]

Walstar, it has been better than a year since your post that you have installed wrap on your stock pipes and box. What do you think about it now?

I am considering wrapping mine but the doom and gloom on this thread seems to mean i am condeming my stock pipes to a 1 year lifespan. With the ZL1k temp problems i would think this is a great thing to do at the very least the sections behind the radiator!

[Bacchus]

Ive wrapped two more bikes since I originally posted up.... no problmes here thus far.... all good and solid like when installed... I dont ride in the rain though....

I can see how if you diddnt treat the wrap, got it wet, and put your bike away for several months you would get rust, but clean dry wrap killing your pipes....naah dont think so. if you ride in wet conditions this treatment may not be for you other wise...works freakin great. looks trick and gets the heat off you and your motor. take a look at where the exaust and the oil pan are.... the exhaust is cooking the oil in the pan, and that is then supposed to cool and lubricate the motor??!! YIKES

my vmax had a temp guage....this treatment dropped that succka way down..... trick is to seal up the wrap with the silicon spray thoroughly...

[WALTSTAR]

I'VE HAD ABSOLUTELY NO PROBLEMS WITH THE WRAP. IN FACT, I TOOK THE STOCK PIPES OFF, GRAFTED A D&D 4 INTO 1 INTO THE POWER CHAMBER AND WRAPPED THEM TOO. YOU WOULD THINK WITH THE THINNER WALL OF THE HEADER IT WOULD BURN THROUGH, BUT IT DIDNT. THE BIKE GETS TO OPERATING TEMP QUICKER AND COOLS DOWN QUICKER. I THINK IT EVEN HELPS COMBUSTION (WHICH IMPROVES PERFORMANCE). I WOULDNT THINK OF BRAGGING, BUT I'VE HEARD ALOT OF TALK ABOUT WHO HAS THE FASTEST ZL ON THIS FORUM..........:pistols: JUST WRAP IT TIGHT AND AVOID GAPS BETWEEN THE WRAP AND THE PIPE. I GROUND DOWN THE BUNGS AND WRAPPED MINE SO THAT THERE WAS A FULL TWO LAYERS ALL THE WAY DOWN THE PIPE.

[killer]

Thank you Baccus and Walstar!!
I will be finding some wrap and goin for it! I love the look and cooler is always better. :blob3:

[kawboy]

Riding in rain is not the only consideration. See the quote below. Google will return lots of similar info. Given the negative info out there, and the relative rarity of the ZL pipes, I would not do it. Does look cool, though. Ceramic coating would prolly be a better option.

"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."

[adrenalinejunky81]

I wouldnt wrap stock pipes, only because think of this... hotter air takes up more space (less dense). If any pipes restrictive at the exit, it would be the stockers. If the pipes can't disperse heat into your legs and back into the oilpan, and instead hold it in...thats going to be hotter air further down the pipe. Any 4-1 performance pipe shouldnt be effected, but it would be cool to see if dyno rusults show this.

[Bacchus]

the idea is to keep the exhaust gasses hot. as the gasses pass through the pipe and lose heat they also lose momentum and slow. this reduces scavangening efect.. wraping the pipes is done to keep exhaust gas hot and fast to provide for maximum scavange

[zl900_moab]

Wow....Lots of info here....Very nice.

moab...