Heat wrapping question

[motorbyclist]

So my mate has some heat wrapping left from working on his car (to stop the pipes cooking things, not some mythical performance gain) and I was thinking about using the leftovers on my NC35 to wrap up the two rear header from where they exit the motor up to where they end behind the heat shield (if i don't run out by then).

The intention is to stop the pipes further cooking my rear shock (heat shield on that is starting to show specks of rust, also) and more importantly, to stop it cooking the underside of my seat/arse. If you've ever ridden an NC30/35 on a hot day you will know exactly what I mean, although the NC35 is much better than the NC30 in that regard...

My question is, could this cause problems by excessive heating of the pipe and/or the exhaust ports?

[CookMySock]

could this cause problems by excessive heating of the pipe and/or the exhaust ports?No. That is almost exclusively a function of your fuel/air ratio. Yes the pipe will no longer be cooled by the high-speed airflow, but that should make little or no difference to anything - steel is intended to get hot. If it has some coating on it, expect that to come off perhaps.

Make sure the wrapping cannot come off though, or you end up with it plus its' reinforcing wire wrapped around your rear wheel.

Steve

[motorbyclist]

No. That is almost exclusively a function of your fuel/air ratio. Yes the pipe will no longer be cooled by the high-speed airflow

no it wont have any problems? or no it won't get appreciably hot....?

righto - it's just the packaging actually had a warning to this effect because the insulation prevents the pipe from cooling, putting it as much as a few hundred degrees hotter than it should be. I'd reckon the metal is obviously going to handle heat well but it could introduce some fatigue problems with the higher operating conditions, so if anyone has actually done it before on a thin walled pipe like this (thin compared to a car) it'd be nice to know...

and there isn't any high speed airflow around the rear of a V4 ;)

[CookMySock]

no it wont have any problems? or no it won't get appreciably hot....? [..] the packaging actually had a warning to this effect because the insulation prevents the pipe from cooling, putting it as much as a few hundred degrees hotter than it should be. I'd reckon the metal is obviously going to handle heat well but it could introduce some fatigue problems with the higher operating conditions...I doubt you will have any problems with that. I haven't done it, but I am planning the same thing (plumbing on rear vtwin cylinder to front-mounted turbo) and I was advised by the muffler man to heatwrap it. Also, the exhaust gas isn't as hot as you might imagine.


and there isn't any high speed airflow around the rear of a V4 ;)I think you will be surprised just how much air moves through there.

Steve

[vifferman]

The only issue might be that if the wrap gets soaked it will accelerate rusting of the headers.

[scumdog]

The only issue might be that if the wrap gets soaked it will accelerate rusting of the headers.

+1

It will wreck the pipes PDQ if the wrap gets wet and doesn't dry out.

[motorbyclist]

I doubt you will have any problems with that. I haven't done it, but I am planning the same thing (plumbing on rear vtwin cylinder to front-mounted turbo) and I was advised by the muffler man to heatwrap it. Also, the exhaust gas isn't as hot as you might imagine.
You're turboing your hyo!? awesome! where'd you get the turbo from?



I think you will be surprised just how much air moves through there.

well they had a reflective shield on the shock but if you reckon so I might just measure the heat to see how hot it gets.... go-go-gadget thumbometer!


The only issue might be that if the wrap gets soaked it will accelerate rusting of the headers.

cheers I hadn't considered that!



It will wreck the pipes PDQ if the wrap gets wet and doesn't dry out.

PDQ?

righto just because i've got to get another 18 months commuting out of this bike and it was going to be a prick of a job anyway, I might leave it for later then as the NC35 isn't too bad for seat-heat anyway, especially compared to the NC30

[kwaka_crasher]

righto - it's just the packaging actually had a warning to this effect because the insulation prevents the pipe from cooling, putting it as much as a few hundred degrees hotter than it should be. I'd reckon the metal is obviously going to handle heat well but it could introduce some fatigue problems with the higher operating conditions

Fatigue is not caused by temperature cycling on such light sections. Given the light wall and small diameter, there will be no appreciable added stress on the tube as the temperature gradient will be very small.

The only issue as others have said is corrosion from moisture. Make it free drain and that problem disappears too. You could pack the insulation off the pipe with some chicken netting to assist drainage.


PDQ?

Pretty Damn Quickly! (Just guessing)

[CookMySock]

@motorcyclist, the turbo was some random junk collected long before I had bikes, but the size and a/r mysteriously seems bloody close. I don't know how it will all work out so keeping it quiet currently just to see how it goes. If it works out mint, I doubt I'll be able to keep my mouth shut about it for long. ;)

Water collecting in it? Even with that amount of heat?

Steve

[gatch]

Yup rust will be a problem if the wrap gets wet, hot steel rusts real quick..

I know what you mean about the heat problem, I own a 89 nc30.

I don't know if it of real concern, but I know nc30s suffer from overheating as it is. Insulating the rear pipes may keep more heat in the engine ? And through the engine to the cooling system ?

I reckon putting some heat shield under the seat and fairing and replacing your shocks heat shield would be easier than trying to wrap the headers in situ, you need 8 yr old asian midget hands to work on anything as it is..

[kwaka_crasher]

I don't know if it of real concern, but I know nc30s suffer from overheating as it is. Insulating the rear pipes may keep more heat in the engine ?

Ironically, quite possibly the opposite (although marginal either way). If hot exhaust gases are passing through a cool pipe (uninsulated) the gases cool increasing density causing the gas velocity to drop correspondingly. Higher velocity assists the draw of the hot gases from the chamber on the exhaust stroke and the velocity will be higher if the gases are not cooled as much, as will be the case in an insulated pipe.

[gatch]

Ironically, quite possibly the opposite (although marginal either way). If hot exhaust gases are passing through a cool pipe (uninsulated) the gases cool increasing density causing the gas velocity to drop correspondingly. Higher velocity assists the draw of the hot gases from the chamber on the exhaust stroke and the velocity will be higher if the gases are not cooled as much, as will be the case in an insulated pipe.

Right on, that makes sense.

So, if you wanted to spend some coin and get your exhaust ceramic coated or what ever is the fashion, would there be any downside aside from a hole in your wallet ?

[imdying]

At the speed the gasses travel and thus the amount of time they spend in the pipe, the amount of heat they'll pick up from a hotter or colder pipe, is negligible. Yes you'll retain more heat in your engine if you wrap the pipe.

[kwaka_crasher]

Right on, that makes sense.

So, if you wanted to spend some coin and get your exhaust ceramic coated or what ever is the fashion, would there be any downside aside from a hole in your wallet ?

That depends on the durability of your wallet traded off against your need for attention because your parents didn't hug you enough.

[motorbyclist]

Fatigue is not caused by temperature cycling on such light sections. Given the light wall and small diameter, there will be no appreciable added stress on the tube as the temperature gradient will be very small. ah no i wasn't concerned for heat cycling but for vibration at the higher (ie weaker) operating temp.



I know what you mean about the heat problem, I own a 89 nc30.

I don't know if it of real concern, but I know nc30s suffer from overheating as it is. Insulating the rear pipes may keep more heat in the engine ? And through the engine to the cooling system ?
yep I used to own a NC30 until some fucker stole it - they don't overheat. they get hot but not overhot as even stationary the fan will keep the temperature from going red, unless your thermostat thingy blew like mine did twice until I gave up and wired in a manual switch ;)

might be worth mentioning that the HRC manual gets you to remove the fan and fit an oil cooler instead



I reckon putting some heat shield under the seat and fairing and replacing your shocks heat shield would be easier than trying to wrap the headers in situ, you need 8 yr old asian midget hands to work on anything as it is..

the NC35 just got some thick black rubber/plastic sheet to impede air coming from the motor and keep fuel/water leaks off the engine, the battery shields the seat and the chassis still gets fucking hot but that's the case for the 800 too... to get at the headers I was going to lift the bike and unbolt the shock from it's top mount to get in there, maybe removing the subframe too...


Ironically, quite possibly the opposite (although marginal either way). If hot exhaust gases are passing through a cool pipe (uninsulated) the gases cool increasing density causing the gas velocity to drop correspondingly. Higher velocity assists the draw of the hot gases from the chamber on the exhaust stroke and the velocity will be higher if the gases are not cooled as much, as will be the case in an insulated pipe.

translation; MOAR POWAH

[kwaka_crasher]

Yes you'll retain more heat in your engine if you wrap the pipe.

No, you won't. Heat comes from the burning gases not being efficiently expelled via the exhaust. When you insulate the exhaust, the hot gases are more efficiently scavenged from the combustion chamber meaning a greater cool incoming charge.

[imdying]

No, you won't. Heat comes from the burning gases not being efficiently expelled via the exhaust. When you insulate the exhaust, the hot gases are more efficiently scavenged from the combustion chamber meaning a greater cool incoming charge.Yes you will, stick a head temperature meter sensor on your spark plug and try it yourself. The difference comes from having a 'really hot' piece of metal bolted to your head instead of just a 'hot' one.

[kwaka_crasher]

Yes you will, stick a head temperature meter sensor on your spark plug and try it yourself. The difference comes from having a 'really hot' piece of metal bolted to your head instead of just a 'hot' one.

Not at all. In the case of headers, the contact area for conduction of heat to the head is limited - two studs and a narrow gasket on each header. In the case of a manifold like a car, a fat insulating gasket.

Not to mention the distance to the combustion chamber from the end of the port and surrounding coolant.

[SS90]

ho hum.

Gasses with higher temperature have less density than colder gasses, and, wrapping your headers will enable more heat to be retained in your headers/exhaust gases.......

What does that mean?

Sweet FA actually, in theory, perhaps faster speed to atmosphere, in reality, nothing.

As far as corrosion goes, it will rust out faster than you can believe.


My advise? Forget about wrapping, it's only any good for lowering under bonnet temperatures, and that is only any real benefit for forced induction.

Wrap the headers only your bike, and with-in a year, you will be looking for replacement ones!

[CookMySock]

Wrap the headers only your bike, and with-in a year, you will be looking for replacement ones!Bugger. I have to wrap only a short section, so I might look a bit of stainless steel for that part.

Steve

[kwaka_crasher]

Wrap the headers only your bike, and with-in a year, you will be looking for replacement ones!

Not if you HPC (http://www.hpcoatings.co.nz/exhaust.htm) them...

[SS90]

Not if you HPC (http://www.hpcoatings.co.nz/exhaust.htm) them...

Er, yes, but if you HPC coat them, then you gain nothing by wrapping them.

[CookMySock]

Er, yes, but if you HPC coat them, then you gain nothing by wrapping them.Surely wrapping is a much better insulator than just HPC on its' own?

Steve

[vifferman]

From threads on the VFRD forum in Mrka, HPC is very rarely long-lasting, even with VERY meticulous surface preparation. I have no idea if there is actually any data to substantiate claims about HPC performance either. I'd thought about getting my own (manky-looking) headers coated, but was rather put off by some of the stories (and the cost). The heat's only an issue for me when the bike spends too much time not moving fast enough. It seems to be more betterer now that I've replaced the mudflap behind the shock with a hugger on the rear wheel = less heat trapped there.

[SS90]

Surely wrapping is a much better insulator than just HPC on its' own?

Steve

Most likely yes, but it depends on the situation.

If for some reason you HAD to wrap your headers, I would suggest using a stainless steel header, as that would resist the corrosion somewhat.

[CookMySock]

If for some reason you HAD to wrap your headers, I would suggest using a stainless steel header, as that would resist the corrosion somewhat.That's what I will be doing I think. My modified and re-routed header is way too close to plastic and oil seals.

Steve