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Manifolds - Wrap or Ceramic anyone interested in a comparison?


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Just wondered if anyone here was interested in doing a comparison test between using Header Wrap and Ceramic Coatings.

 

I ask as I will be fitting a new set of Stainless Manifolds over the winter, and have to decide if I Wrap them or try Ceramic Coating.

 

Now I know that the choice is a bit like Marmite, people either love one and hate the other. I'm not out to convince anyone either way, or actually start a long debate about why people think one is better and for what reasons.

 

What I'm actually interested in is getting some real test results as I can find no actual comparisons on the web, well I can but they are either totally subjective and of the I think its much better now I have spent $300, or they are the sudo manufacturer tests where they make impressive claims, but with nothing other than bare metal as a comparison, or use some weird radiant heat measured a few inches away from the manifold.

 

So I though there must be enough of us on this forum with ceramic and wrap that we could set up a test something like running engine for 20 mins and then taking surface temperature readings at a few designated spots, and then producing a table of the results. Not hugely scientific but better than anything I can find.

 

Anyone interested?

 

Alan

 

 

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....before you do anything, make sure they fit the engine/car/exhaust system to your satisfaction, and run without leaking.......

 

Peter W

 

PS I wrapped mine. using the stuff the motorcycle riders use.

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Hi Alan,

I was going to do exactly as you have laid out a few years ago but in the end things overtook me and I fitted the pipes before measuring.

 

The TRactor wrap functions and gives a thermal barrier such that you can touch the pipes when running.

However the disadvantages were too many to continue with it. That was on a Revington manifold.

 

When I changed to a Phoenix manifold I decided to get them ceramic coated whilst they were still new.

I went for the CamCoat product. This gave a layer on the inside and two layers on the outside (3 layers in all).

I don't feel brave enough to touch the pipes but I would suggest it was no worse than the wrap.

The exhaust gases are significantly hotter with the ceramic so much so that the bumper turned blue. A crude test but suggested that the ceramic was keeping the heat in the pipes.

 

If you decide to take Infra Red thermal readings then you need to have the reading surface a uniform colour for all tests - matte black is best.

Brighter colours may affect the reading.

 

 

Roger

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Roger

Are both those manifolds 4 into 1 ?

 

Ill be interested in this test. Also what manifolds people have.

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Hi Alan,

I'll try to take a reading but I'll have to invent the IR camera first.

 

Hi Iain,

after a good drive I reversed into something and the tail pipe pushed the downpipe forward and was touching the chassis. I couldn't straighten it out.

 

Hi Hamish

yes.

 

Roger

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My Phoenix are naked and give no problems (Tr6 PI).

 

Never sure about sending the heat rearwards down the car and with a transverse silencer box under the fuel tank and adjacent to the pump it would presumably increase the boot temperature and eventually the fuel temperature.

 

I'm not opposed to wrapping just never had the need to. If I had a high revving race engine then I would think it would be essential.

 

I have an IR thermometer and if you have any specific requests for temperatures then I'm happy to assist.

 

 

Alan

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Alan OTUnder,

You're after max effort, right? Then the last thing you want to do is keep heat in the gas. Coatings will keep the gas hot and expanded, creating more back pressure.Not good. Coating/wrapping was a trick for turbos and has no place in n/a engines fitted with a proper cold air intake.

Peter

Edited by Peter Cobbold
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IMHO, wrap does weird things to mild steel headers. Does in go anoxic under there?

I once wrapped one, and when the wrap got tatty, as it will,took it off again. Flakes of corrosion, bluey purple came off from underneath, not normal rust. So thick, the OE metal must have been thinned.

 

And what about chromium depletion? Weld Stanless and carbides form, inc chromium carbide. No chromium so no stainless. Under wrap, the metal might get hot enough?

 

John

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OK I sought of thought this might Marmite.

 

I don't care if Mild Steel wrapped rots, in fact from my own empirical real world testing it does. I don't really care if Stainless headers turn to Blue Cheese after 3 years, What I do care about is under bonnet temperatures and how hot my carbs get. Cold Carbs = Good, Hot Carbs = Bad.

 

At Prescott in early July when it was hot I was measuring a few carb temperatures on cars when they returned to paddock and some were at the temperature where if the float chambers had been open to atmosphere the current batch of crap we call fuel would have been dam near boiling, whereas on my car with wrapped headers and a large amount of heat shielding I was recording temperatures about 20C lower.

 

On a hot day sit on the start line for 5 mins with engine up to temp and nothing but the fan keeping the engine at working temp and very little air flow through the under bonnet and things get hot. So just when you want everything working properly its all hot, then you ask the engine to give its best for 60 secs before any air flow is going to have any significant effect

 

So if a set of wrapped or coated headers only lasts 4 years, just think of it as a wear item.

 

In my experience every time you remove wrapped headers, it starts falling apart, and requires some remedial or a re-wrap, and if your doing that once a year and using good wrap not the cheap fibreglass stuff, then over 3-4 years its probably not far off the cost of ceramic coating.

 

So I'm not worried about the cost (well no more than I normally am, which is usually) what I can't find anywhere is someone, anyone who has actually measured the difference in the same (or similar) cars between the two. Sorry I have reached the age when someone says product x is way better than product y, i want some facts not just vague supposition.

 

I'll coat if it really works as well as wrap as it will save some hassle, but I don't wan't want to coat and then find I have to wrap as well.

 

Alan

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Underbonnet air filters are nbg- big power losses there from low density hot air. Fit bonnet scoop and plenum. Or a large bore hose from front of rad, fan fed to keep cool air flowing through a plenum past filters while standing.

Fit a reflective shield under manifold and carbs, and polish the outside of the intake manifold,both as Vizard recommended.

Vizard gave some numbers on radiant vs convected heat from ex to intake manifolds.....radiant won easily. So if covering the ex manifold is still on the cards find out which radiates the least heat. That will scale with lower surface temperature and the better insulation. My guess: wrapping

All float chambers I've ever come across are open to atmosphere.....

Peter

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I think I've been shot down here before, but the temp differences are about the same while the "ceramic coatings" are so different that one is a scam. Makes me sceptical about the one.

 

What? Exhaust coatings are millimeters thick, the ceramic tiles on the Space Shuttle inches thick.

John

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The shuttle tiles were ablative John - intended to burn away hence some considerable thickness is required and you only use them once.

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Hi John, since the days of my good old friend GT with his fabulous headers

I would like to see a test done from a person I can rely on.

My personal opinion is that an exhaust header does less than expected on a TR6 with 2 branch cast iron header

but some of my friends claimed some power increase and -loss just from different headers.

 

From my view the fitment must include a new setting of fuel.

In the old days I learned that I had a bad/original muffler on my Lotus 16V

Not expected I gained a huge 18hp increase in the lower midrange by

swapping to a muffler from BMW turbo and resetting carbs.

The nasty feeling that such a power loss might be hidden in my engine is not nice.

 

Today I do not put my engine on the bench and I do not swap headers because

its a pain to fit and they are expensive. Some of them like the Bastuck and the GT

do not fit without tricks and so once fitted they will stay for lifetime.

 

I offered GT to buy some of his headers if on the bench they will do what he promises

against my actual 6-2-1 header. He did not want to lend one for testing.

This convinced me in my opinion that the results may not be like expected.

 

I see the difference not mainly in wrapped or coated or mild or stainless but in the header itself.

 

Also some different mufflers must be tested with each header.

I learned they have some influence, too-

 

So every test will become quite expensive and that might be the reason, that we do not have data yet.

 

We are in the comfortable position that people who are interested in these headers use similar engines.

For the TR4 I would expect a mildly tuned engine with a cam between 270 and 300 degrees and

displacement between 2.1 and 2.4 litre. That is pretty close together to transfer the result to others!

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Hi Alan,

looking at the 'test' in isolation a great many variables need to be put aside before testing can begin.

Ideally you need one engine and carb set-up plus three fairly similar manifolds - naked, wrapped, coated.

 

Then take the temps from the same places on each occasion after reasonably identical runs.

 

To assemble all the bits we ar looking at apprx £1000. Too much for the average punter. A club project for the TRR perhaps - are the technical team interested

 

Roger

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In the days when racing motorbikes had 'megaphone' exhausts, that sent a shockwave back up the pipe, there was a 'sweetspot' (revs wise) where the negative wave sat at the exhaust valve.

Obviously a WAG, but suspect the exhaust headers are similar, help a bit over a range with less resistance to flow, but at their best in a particular rev band because of the shockwave.

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Alan,

I have no experience in difference in skin temperatures between ceramic coated and wrapped headers, but have done many Infra red surveys on refinery equipment.

Some facts:

Be carefull when you measure "shiny" surfaces, including even brownish SS with an IR camera.

The emissivity factor needs to be adjusted in the camera, difficult to establish the factor for most of us.

The total amount of heat dissipated is the sum of rariation, convection and conduction, but is nothing new.

Black painted equipment has a lower skin temperature than silver (it has a higher emissivety factor ("emission"), so if you what to coat to reduce radiation, use silver instead of black.

The amount of radiation is to the fourth power with temperature.

The heat has to travel through the metal first (conduction), and the skin temperature is largely determined by the thermal conductivity (TC) of the metal, which is "high".

Adding a thin layer of a ceramic fibre wrap which has a very low TC will give very big reduction in the skin temperature.

 

I think adding a thin coating of "ceramic paint" will be less effective, since the change in TC of this thin layer will not being much- but again: this is not based on actual measurements.

A thicker wall thickness reduces the skin temperature (a cast header will be better for that aspect.

 

Like Peter indicated, for pressure/flow reasons it may be benificial to reduce the exhaust gas temperature, which is a conflicting requirement.

 

FWIW:

I will not race my TR6, and will blast and paint my cast manifold with a heat resistant silver paint. Good enough for me.

 

Regards,

Waldi

Edited by Waldi
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Hi Guys

 

Day out in the field and you have been busy, sorry for delayed response

 

 

Hi Alan,

I'll try to take a reading but I'll have to invent the IR camera first.

 

 

 

 

I have a cheap Laser Thermometer and also a temperature probe, I'll happily pop them in the post if you'll take some readings.

 

 

 

 

I have an IR thermometer and if you have any specific requests for temperatures then I'm happy to assist.

 

 

It would be good to get some readings of a plain set, we may find they are all rubbish!

 

You're after max effort, right? Then the last thing you want to do is keep heat in the gas. Coatings will keep the gas hot and expanded, creating more back pressure.Not good. Coating/wrapping was a trick for turbos and has no place in n/a engines fitted with a proper cold air intake.

 

 

I thought the objective was to keep it hot and moving quickly for a specific distance, however my main objective is under bonnet temp reduction.

 

Underbonnet air filters are nbg- big power losses there from low density hot air. Fit bonnet scoop and plenum. Or a large bore hose from front of rad, fan fed to keep cool air flowing through a plenum past filters while standing.

Fit a reflective shield under manifold and carbs, and polish the outside of the intake manifold,both as Vizard recommended.

Vizard gave some numbers on radiant vs convected heat from ex to intake manifolds.....radiant won easily. So if covering the ex manifold is still on the cards find out which radiates the least heat. That will scale with lower surface temperature and the better insulation. My guess: wrapping

All float chambers I've ever come across are open to atmosphere.....

Peter

 

I have acres of heat shield to duct cool air to the carbs both for cooler induction charge but also to keep the carbs cool.

Yes I'm trying to find out which radiates the least heat.

Sorry when I said open, I meant if they were open like a pan the fuel would have been boiling away.

 

I think I've been shot down here before, but the temp differences are about the same while the "ceramic coatings" are so different that one is a scam. Makes me sceptical about the one.

What? Exhaust coatings are millimeters thick, the ceramic tiles on the Space Shuttle inches thick.

 

I think if you look at the blurb on Ceramic coatings rather than millimetres they are actually in the 11-15 thou range, which is why I have questions. I know on a stove top that metal, glass, and ceramic pots all transfer heat to the ingredients fairly quickly, but that's obviously not a magic thin film of the correct ceramic.

 

 

 

So every test will become quite expensive and that might be the reason, that we do not have data yet.

 

We are in the comfortable position that people who are interested in these headers use similar engines.

For the TR4 I would expect a mildly tuned engine with a cam between 270 and 300 degrees and

displacement between 2.1 and 2.4 litre. That is pretty close together to transfer the result to others!

 

That's sort of where I was aiming if we could just measure surface temperatures at similar points, on similar cars, at say a similar base like 1000-1500 rpm after getting fully warm (say 15/20 mins idling) It would al least give us something comparable, if not totally scientific, but very cheap for us to do as the only cost would be the fuel using getting engines up to temp.

 

 

Hi Alan,

looking at the 'test' in isolation a great many variables need to be put aside before testing can begin.

Ideally you need one engine and carb set-up plus three fairly similar manifolds - naked, wrapped, coated.

 

Then take the temps from the same places on each occasion after reasonably identical runs.

 

To assemble all the bits we ar looking at apprx £1000. Too much for the average punter. A club project for the TRR perhaps - are the technical team interested

 

Roger

 

That's why I thought we might devise a test that we could individually run on fairly similiar cars with different header manifold treatements, very low cost.

 

 

 

Alan,
I have no experience in difference in skin temperatures between ceramic coated and wrapped headers, but have done many Infra red surveys on refinery equipment.
Some facts:
Be carefull when you measure "shiny" surfaces, including even brownish SS with an IR camera.
The emissivity factor needs to be adjusted in the camera, difficult to establish the factor for most of us.
The total amount of heat dissipated is the sum of rariation, convection and conduction, but is nothing new.
Black painted equipment has a lower skin temperature than silver (it has a higher emissivety factor ("emission"), so if you what to coat to reduce radiation, use silver instead of black.
The amount of radiation is to the fourth power with temperature.
The heat has to travel through the metal first (conduction), and the skin temperature is largely determined by the thermal conductivity (TC) of the metal, which is "high".
Adding a thin layer of a ceramic fibre wrap which has a very low TC will give very big reduction in the skin temperature.

I think adding a thin coating of "ceramic paint" will be less effective, since the change in TC of this thin layer will not being much- but again: this is not based on actual measurements.
A thicker wall thickness reduces the skin temperature (a cast header will be better for that aspect.

Like Peter indicated, for pressure/flow reasons it may be benificial to reduce the exhaust gas temperature, which is a conflicting requirement.

FWIW:
I will not race my TR6, and will blast and paint my cast manifold with a heat resistant silver paint. Good enough for me.

Regards,
Waldi

 

Great input, and sound like you might be able to interpret any results better than I can. However I'm assuming if we all used similar IR Thermometers onto a small black/dark patch on the headers, the results should at least be able to be compared?

 

 

This is what I did to provide cold air to the carburettors.

 

 

That's an improvement on a lot I see with no ducted air towards the air filters, where they are breathing really hot under bonnet air. Most of the original Triumph inlet Plenum's were designed (if not always efficiently or in great enough volume at high rpms) to get cold clean air to the carb's.

 

 

I'll do a drawing later of what I think might be good measurement points, and see what people think.

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Alan, What really matters is the temperature of the mixture approaching the inlet valve. Measuring a liquid/gas mixture's temperature accurately is imossible - its not uniform. But you could take readings from a thermocouple sensor in the manifold mixture flow to compare effects of shielding, wrapping etc when driving. Comparing the air intake at the mouth of the carb and near the inlet valve would be intresting - fully evaporated mixture should drop temperature by about 18C. You'd get an idea of heat transfer from the manifold to the mixture at various rpm.

Your logger can do that I think?

Peter.

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Quote:

"Great input, and sound like you might be able to interpret any results better than I can. However I'm assuming if we all used similar IR Thermometers onto a small black/dark patch on the headers, the results should at least be able to be compared? "

Unquote.

 

Yes Alan,

If you mark an area with black paint, you can measure pretty accurate, also on a ss exhaust.

The spot you paint should be large enough: although the little red dot may suggest it can measure a very tiny spot, that is only the case with very expensive IR cameras.

Some IR cameras show the required area, which is depending on the distance.

Regarding the paint:

Black or dark grey-ish will all give a pretty close result, the change in emissivity it not that big.

Check the temperature range of the camera.

A rusty steel surface, also a casting (but not brownish SS) could be measured without painting it black, the difference in reading will be small (try it if you like).

 

A bit off topic:

Another usefull application is to compare exhaust temperatures from individual cylinders to compare combustion.

 

And also off topic: 40 years ago I was definitely doing something else on saturday night:)

Regards,

Waldi

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We need to be careful in trying to judge emissivity from visible color. Emissivity is determined over a much wider band that that which determines color.

 

Most ordinary flat paints have similar emissivities, regardless of color. In fact, a non-flat black paint would almost certainly have a lower emissivity than a flat white.

 

One trick sometimes used to measure a shiny surface is to apply typist's White-Out. It is easily applied, easily removed, and has an emissivity of 0.95 or better.

 

Ed

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