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Manifolds - Wrap or Ceramic anyone interested in a comparison?


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Hi Waldi

 

Your talking IR Cameras, how about the simple IR thermometers we can all buy for around £13 $20 ?

 

Yes I always check all 6 exhaust pipes, its a quick way to tell which cylinder has a random misfire etc, always surprised how much difference in temp between a cylinder that is firing but not every time and a good one.

 

Peter

Wish I could log that! Well not saying the logger couldn't if I could sort the inputs. But so far all I know is from testing that keeping the carbs cool and feeding then cool air makes a significant difference.

 

Alan

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Alan,

Sorry for not being clear.

At work I use the advanced camera, it provides an "image" with several adjustments possible. Costing several thousands euro's.

In my garage at home I have a simple pointer-type, the better name is IR thermometer, think is was 15-20 euro. It has a temperature range of -20 to +320 C. Nothing can be adjusted.

At a distance of 20 cm it requires (measures) a spot of 25 mm in diameter.

At twice this distance the area should be 50 mm etc.

 

Ed is correct (as always).

At work, we use a fixed value of 0.94 for the emissivity, after we found out the difference in measured temperature is marginal for the measurements / inspections we mostly do.

But for shiny surfaces like aluminium clad we need to adjust the emissivity, and you can be 50c (or more) wrong, easily.

With the simple thermometer such adjustments are not possible, but for our purpose that is acceptable.

But like said: it will give a large misreading on a shiny surface, even on an older ss manifold.

Hope this helps.

Regards,

Waldi

Edited by Waldi
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Peter

Wish I could log that! Well not saying the logger couldn't if I could sort the inputs. But so far all I know is from testing that keeping the carbs cool and feeding then cool air makes a significant difference.

 

Alan

Alan,Have a passenger do the logging ,from one of these:

https://www.amazon.co.uk/Thermometer-Thermocouples-Industry-Agriculture-Meteorology/dp/B01HB9QN44/ref=sr_1_6?ie=UTF8&qid=1510503803&sr=8-6&keywords=thermocouple

Does two channels, up to 300C so good for the air flow temps.

 

Thee must be similat thermocouple or thermister meters that put out 0-5 volt signal suitable for a logger....

=======

And to see how much power hot intake air drops these data are useful:

https://www.engineeringtoolbox.com/air-density-specific-weight-d_600.html

So 20C to 50C lowers density about 1.11/1.2 or 8% power loss.

 

 

Peter

Edited by Peter Cobbold
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Imaging video cameras to rgeuster infrared are indeed very costly.

But iof you have an old 35mm film camera, you could buy some infrared film!

 

See: http://www.ebay.co.uk/bhp/infrared-film

 

Never used it, and some of that on sale is 'old stock' but cheap as chips, in comparison.

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.

 

My apologies for not seeing your response sooner, Rob!

 

And I have to disagree - the Shuttle tiles were, specifically and I quote, "reusable". Previous re-entry vehicles did have ablative ceramic coatings, and the Shuttle's tiles were closely inspected and replaced if necessary, but could have survived the expected 100 flight life of a Shuttle if they did not deteriorate.

 

And tiles were one to four inches thick - this contrasts with the thickness of the ceramic coating on an exhaust, measured in fractions of a millimeter, when the temperature outside the Shuttle on re-entry was only about twice that inside an exhaust primary.

John

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Agreed John. Re-usable if not ablated, but if noticeably abalated they were replaced - but more to the point the purpose was rather different which was what I was trying to convey. The tiles were to protect the aluminium structure of the shuttle with its low melting point, to prevent structural failure. That is not a consideration for a steel exhaust header. The tiles had to reduce the 1000C + temperatures down to around a couple of hundred hence the thickness.

Completely opposite to the shuttle use, the exhaust pipe materials will be even hotter when coated. The ceramic on the exhaust presumably is not intended to burn away (just as well given the cost) but just to decrease the thermal conductivity from inside to outside (and perhaps the external surface emissivity? ) so does not need to be anything like as thick to reduce the engine bay temperature enough. I bet the outside temperature of the coated pipes is still plenty hot.

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Rob,

The applications are exactly similar. The Shuttle to protect the airframe from heat, you to protect the other contents of the engine bay from heat. Why does one need four inches, the other 0.3mm?

 

John

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Perhaps because one is a safety-critical application to ensure specific temperatures are never exceeded while the other is a 'hope-it-works' to reduce temperature a bit but with no specific numerical goal. I found this interesting comparison test though the specific coatings are not named:

http://insulationinstitute.org/wp-content/uploads/2016/01/CI224.pdf

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Very interesting, Rob! The "executive summary" is devastating:

 

"The testing shows that the coatings, even at thicknesses that are above those typically installed in field use, are three times less effective as insulators than ½ inch of mineral fiber insulation."

 

John

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Here is a product I use, that genuinely works.

http://www.laco.com/heat-protection-products/bloc-it-/

 

Peter W

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Here is a product I use, that genuinely works.

http://www.laco.com/heat-protection-products/bloc-it-/

 

Peter W

Saw Ed China use this stuff to prevent panel distortion on a long, thin metal, repair.

 

Clever stuff

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Hi John,

I think Rob is pretty much close to the mark in that the exhaust pipe ceramic is not trying to cut all heat transfer into the engine bay.

There is just too much heat being supplied by the block, radiator etc to win.

 

It is there to take the edge off the total input.

 

With the normal airflow when travelling the rad and block are kept under reasonable control and the under bonnet temp is OK.

However the bare pipe will input a fair amount especially when stationary

If the coating can remove 10'C or a little more then that must count as an improvement - is it good enough !!! I don't know.

 

With the shuttle ALL the generated heat must be stopped. Aluminium and its alloys are rubbish when the temp rises. One moment it is there. the next, it is not.

 

So there is a difference of expectation.

 

The shuttle tiles do work - it has been calculated and proven in real life

The ceramic pipe coating does work - Physics says so

 

 

Roger

Edited by RogerH
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Interesting paper that - good find Rob!

 

For me, the kicker has always been the exorbitant cost of ceramic coating. It just exceeds my spend threshold by such a large margin it will never get a look in.

 

Fortunately injection is much less fussy than carbs and I have very few heat related issues even with an uninsulated tubular manifold.

 

Nick

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Hi Nick,

clearly price has a major impact on whether ceramic is used or not.

Even the TRactor wrap is not cheap.

 

From my point of view I simply liked the idea of technology trying to help and also the ceramic coating (CamCoat product) gives a very clean durable finish.

 

Roger

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Indeed, Roger!

 

My old race Vitesse was an experiment in aero, with the radiator in the back. It wasn't a complete success, there is a reason why they are usually frontal, but it showed the relative importance of the various heat sources under the bonnet.

Drivers of small chassis Triumphs often complain of excess heat when driving, and spend a lot on gearbox cover insulation etc. Not as commonly complained of in TRs but then you don't have a roof, do you?!

My rear radiatored car was very cold to drive, and cold under the bonnet, because all that excess heat - is it 60% of the fuel burnt? - was going out of the back, not under the bonnet.

 

As for that special heat-absorbing paste, what's wrong with wet newspaper?

Wrap it around the pipe, lay it on the panel. Nothing under it can get to more than 100C.

 

John

Edited by john.r.davies
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Here is a product I use, that genuinely works.

http://www.laco.com/heat-protection-products/bloc-it-/

 

Peter W

Looks useful stuff Pete. I had a look at whats in it (SDS page) and it's based upon a rare mineral hectorite

https://en.wikipedia.org/wiki/Hectorite

Ingenious !

Peter

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Indeed, Roger!

 

My old race Vitesse was an experiment in aero, with the radiator in the back. It wasn't a complete success, there is a reason why they are usually frontal, but it showed the relative importance of the various heat sources under the bonnet.

Drivers of small chassis Triumphs often complain of excess heat when driving, and spend a lot on gearbox cover insulation etc. Not as commonly complained of in TRs but then you don't have a roof, do you?!

My rear radiatored car was very cold to drive, and cold under the bonnet, because all that excess heat - is it 60% of the fuel burnt? - was going out of the back, not under the bonnet.

 

As for that special heat-absorbing paste, what's wrong with wet newspaper?

Wrap it around the pipe, lay it on the panel. Nothing under it can get to more than 100C.

 

John

About 30% of fuel burned.

Sankey diagram:

http://www.sankey-diagrams.com/wp-content/gallery/o_sankey_209/dynamic/energy_split_combustion_engine.png-nggid03260-ngg0dyn-500x0x100-00f0w010c010r110f110r010t010.png

 

Peter

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Perhaps because one is a safety-critical application to ensure specific temperatures are never exceeded while the other is a 'hope-it-works' to reduce temperature a bit but with no specific numerical goal. I found this interesting comparison test though the specific coatings are not named:

http://insulationinstitute.org/wp-content/uploads/2016/01/CI224.pdf

Very interesting Rob. Looks to me that wrapping will win, easily. Peter

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As far as I can tell the cooler the air into the carbs the denser it is thus more power available.

 

Very hot air is a bit like loosing power due to altitude over the mountains due to thin air.

 

And why many sporting or race version of cars had air intakes like the TR4 and healey 3000 rally cars. That have them in the wings.

 

But Im open to correction.

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We can all appreciate a lower underbonnet temp is usually a good thing but I'm still struggling to find any evidence that insulating the manifold offers any performance benefit?

Only way to know is to measure the carb air intake temperature without/with insulation, and allow for ambient changes,driving/stationary etc

Inlet valve mixture temp is much more difficult, impossible if wet fuel is present.

Peter

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As far as I can tell the cooler the air into the carbs the denser it is thus more power available.

 

Very hot air is a bit like loosing power due to altitude over the mountains due to thin air.

 

And why many sporting or race version of cars had air intakes like the TR4 and healey 3000 rally cars. That have them in the wings.

 

But Im open to correction.

Yes, the engineerig toolbox link I posted above will give you numbers. Several percent lost from hot air intakes, that's maybe 10hp on aTR. Its costs real cash to gain 10hp so cold air intake is easily the cheapest tweak I know. ( And vice versa !! )

 

The really difficult bit is how much heat is picked up between carb and inlet vaves in the manifold. Heat gain there expands the gas, raises pressure a tad and the flow through the carb will drop. But it is impossible to measure the temperature of a mixture of air and fuel droplets. Vizard in a book covered manifold heat pick up but I've lost the reference. Maybe he briefly cut the fuel supply to one carb to get a dry temperature measurement on a running engine.

There's lots of scope for testing using very cheap kit, as I posted earlier. Maybe 10 hp won for £20.

Peter.

Edited by Peter Cobbold
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