ESE's works engine tuner

**F5 Dave** · 5th February 2009, 15:54

I'm typing with one hand for next 6 weeks so won't elaborate, but we covered it last week in some thread here in buckets. Basically some charge disappears into header & returns with pipe pulse. I think a lot of it is swings & round abouts.

**TZ350** · 5th February 2009, 19:28

Originally Posted by Fooman

Not so sure about the combustion space, but coatings even out the temperature of the substrate material (i.e. what the coating has been put on). If the substrate is sufficiently cooled (i.e. enough heat been taken away), then the poor thermal conductivity of the ceramic coating means that the substrate doesn't get the chance to heat up (as much). Hot-spots are "deposited" energy, like water in a sponge - if you waterproof a sponge it can't soak up water, so by coating a metal, you "heat" proof it to some degree - the energy does not get transmitted through the insulation to cause the localised heating in the substrate. Actually, I quite like that analogy!

Actually the thermal emissivity of a object is not necessary related to it's colour - some things which look black in the visible spectrum may not behave like a black body in the IR spectrum - however, it is a good rule of thumb. Anyway, regardless of the colour of a ceramic coating, if it is there and the ceramic has lower thermal conductivity than the uncoated material (e.g. steel), there will be a greater temperature drop through the header wall - it will be cooler on the outside for the same exhaust temperature. A higher emissivity may mean that the cooler exhaust loses it's heat quicker, but it will be minimal (i.e. may be 0.90 rather than 0.80 (oxidised steel/cast iron), and I suspect the cooler skin temperature will dominate.

So, what will happen is the exhaust flow will not cool down as much, and therefore the heat that has not been lost at the headers will be lost somewhere else (out the back or in the muffler or under the body).

As a point of reference for you - note the following webpage:

http://www.newportus.com/Products/Techncal/MetlEmty.htm

Cheers,
FM

As always FM you make some very good points.

Looks like I will have to change my:- Mat black Exhaust + Exhaust Heat = Cooler under Bonnet!!! Not Likely

To:- " Not very significantly"

I can see from your explanation how a ceramic coatings thermal insulating properties would allow the substrata underneath time to even out its hot-spots but I suspect all it means is that the ceramic becomes the hotter hot-spot instead.

Coba quotes Graham Bell as not thinking ceramic coatings have much to offer high performance engines.

Dale Alexander in "Squish It Until It Makes Power" (RD350s & 400s) talks of the temperature of the piston crown as being the limiting factor in making power and he used ceramic coatings on the pistons to reduce their thermal load. His coating's were three layers and 0.020" thick not the poxy thou or two you get from the Specialists! He specifically describes thin coatings as usless.

I can see how this works as the fire spends longer up in the roof of the combustion chamber and comparatively little time really close to the piston. So
the ceramic on the piston crown gets hot (but the piston crown is cooler) and the ceramics face is not as hot as it would have been if it was on the combustion chamber roof. Possibly??

Could it be that ceramic on the piston does not get as hot as the other uncoated parts of the combustion chamber, would that be possible? Could the face (fire side) of the ceramic coating on the combustion chamber find itself running much hotter than the ceramic on the piston crown?

Thats a great chart on emissivity, see how aluminum has really low emissivity even when oxidized. I did not realise it was as bad as that. I really should grit blast my head and paint it black with lamp black paint. I am sure your right, not all blacks have the same emissivity.

Thanks for the chart.

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**TZ350** · 5th February 2009, 19:30

Originally Posted by koba

Just ran out of time but the second edition of A. Graham Bells book has a bit on ceramic coatings.
His conclusion is basically that it should only be any good on slow speed low throttle engines that lose alot of heat energy per cycle and it would be detrimental on a high speed competition engine.

Now that is very interesting!

.

**TZ350** · 5th February 2009, 19:34

Originally Posted by F5 Dave

I'm typing with one hand for next 6 weeks so won't elaborate, but we covered it last week in some thread here in buckets. Basically some charge disappears into header & returns with pipe pulse. I think a lot of it is swings & round abouts.

Sorry to hear your hurt,

but thanks for the thoughtfull and often amusing input to the various posts.

.

**Yow Ling** · 5th February 2009, 20:13

TZ you have been putting alot of effort in trying to reduce the heat transfer from the barrel to the crankcase, maybe this is a wasted effortthe temp at the base gasket i pretty low, You talking about ceramics made me think that the real problem is radiated heat from the inside of the piston crown. It gets hot there sometimes hot enough to melt the aluminium (660 deg C) maybe this is a bigger problem than the other. The cool charge is doing double duty here in that it provides cooling inside the piston lubricating the bearings and cylinder and finaly providing the heat to continue the cycle. coating the piston with some flash stuff seems on the face of it a good plan

**TZ350** · 5th February 2009, 20:47

Hi Yow Ling

Yes I think coating the piston is worth doing to reduce the conducted and radiated heat from the underside of the piston crown. I will get one done. It may take a few weeks as I want to get a .020 coat like Dale Alexander talks about and I don't think I can get that locally.

There is a gully port at the back of the cylinder that is feed by a hole in the piston. Part of the transfer stream goes up-inside the piston and cools the underside of the piston crown which heats up the air-fuel charge by conduction and radiation as its cooling the piston.

The charge then goes through the hole in the piston and up the back boost port into the combustion chamber. There is a photo in an earlier post where you can see the hole in the piston.

Tomorrow I will (hopefully) get the copper head gasket/fin finished and everything assembled for a tryout at work. The fin bit does not look much but it adds about 580 sqr centimeters of fin and then there is the 4 CPU heat sinks. Which I should have anodised mat black.

No fans as I am frightened that everything will get hot enough to melt the them. With the copper fin and CPU heat sinks the fin area of the head has more than doubled.

Yes I know the CPU heat sinks are quite away from the combustion chamber but I am picking the greater thermal conductivity of the copper fin will move heat to them quicker than the original alloy head can move heat to its outer fins. I will have a look at the relative temperatures to see if I am right.

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**Buckets4Me** · 6th February 2009, 07:49

Originally Posted by TZ350

.

Why copper and not ceramic?

Well we were all for ceramic coating the combustion chamber to keep the combustion heat in and get more power out but then thought about it a bit and read some on the Internet and concluded that performance ceramic coating specialists were talking more advertising true speak than making technical sense.

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let me see if I have got this right
you are using copper instead of ceramic because

1. you are trying to get rid of heat from the head (not trying to keep the heat in the chamber and out the exaust with ceramic)

2. you think the ceramic would stop the head doing it's job and also get to hot on the face of the ceramic

3. you havent got the time or money to try both

4. you havent worked out how to wrap the head in ice (and have the ice last 2 hours)

**TZ350** · 6th February 2009, 08:06

Originally Posted by Buckets4Me

let me see if I have got this right
you are using copper instead of ceramic because

1. you are trying to get rid of heat from the head (not trying to keep the heat in the chamber and oput the exaust with ceramic)

2. you think the ceramic would stop the head doing it's job and also get to hot on the face of the ceramic

3. you havent got the time or money to try both

4. you havent worked out how to wrap the head in ice (and have the ice last 2 hours)

1. Use your spelling checker. "oput the exaust" Sheeeeeesh !

2. "the ceramic would stop the head doing it's job " Yes, that is my conclusion, its the boundry layers job to keep the heat in the engine.

Once any heat gets to the head it needs to be shed quickly.

3. You are right about "Time and Money" you must know me!

4. That darn ice keeps melting.

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**TZ350** · 6th February 2009, 19:03

Got it all together.

Picture-1. All the parts.

Picture-2. Underside of the complete assembly, I am running a flat piston, the copper fin extends right into the combustion chamber and forms the squish band.

Picture-3. Top side of the assembly, I have now painted the alloy head black.

Picture-4 Thomas doing a test assembly of the parts and making sure there is the correct squish clearance.

Picture-5 The bike just before its first run.

Picture-6 Thomas and Jan doing the cam belt on Thomas's "Fast Four".

The test run was just up the drive, around the car park and back!

I felt the copper head fin and it was just warm. The head was cold. This confirmed what I was expecting, That the copper transfered heat out of the combustion chamber much quicker than the original alloy head. After a minute or so of sitting the alloy head started to feel warm too.

I was also expecting this, it confirmed what I thought, that the alloy soaked up the combustion chamber heat but it was getting out to the fins through the alloy much slower than it does through the copper fin. The copper fin cooled off much quicker than the alloy head. No surprises there either.

After a run up the drive, around the car park and back. The head and copper were no more than just warm.

The big surprise was that when I felt the fins under the barrel they very nearly burnt my hand. They were so hot that I could not keep holding them. There is three fins under the barrel and the bottom fin felt as hot as the top one. So the heat transfer between them is good.

The under barrel fins getting so hot so quickly it absolutely floored me, the under barrel heat must have been there all the time and going into the crankcase. I am so glad I put a heat insulating washer between them and the crank case. It will be interesting to see if the cases run cooler now.

The head fin is a bit OTT. And if I was doing this again I would make a smaller simpler head fin but definatly put multi finning under the barrel.

Why the under barrel fins got so hot and would they remain hotter than the head fins during a race, I don,t know! but that is the first place I would put any copper finning on a new motor.

Hopefully on Sunday we will have a heat gun to read the tempartures and fingers crossed the bike runs long enough to get some good readings.

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**koba** · 7th February 2009, 08:50

That is so coool!
It is great to see it all looking so promising!

**Buckets4Me** · 7th February 2009, 12:44

where is the heat coming from at the bottom of the barrel

whould have thought that most or all the heat was near the head

is it that the heat is dissapated faster up top but not down below ????

see you sunday both bikes are back together but havent started either yet

couldn't find what i did with the kick start
and it's to hot to go out side

now to get an ice cream

**TZ350** · 7th February 2009, 13:21

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I thought most of the heat would be all up top too.

As it was just a little ride up the drive and back I was not expecting any heat in the under barrel fins at all.

I think the heat is coming from the exhaust tract.
Whether the under fins remain unexpectedly hotter than the head fins after every thing gets a good heat soaking during a race I don't know.

It could be the under fins get up to temperature quickest. Hopefully know more tomorrow.

I have the Red bike running and will take it for you to use tomorrow.

Will get you to run my bike around for a bit in practice while I take temperatures and play with the jets if thats OK with you.

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**craisin** · 8th February 2009, 07:16

So i had an idea that since the crankcase is part of the intake tract and on the side is a hot sweaty gearbox with no provision to let the hot air expand and cool because the gearbox is not vented . My idea was to make a ram-air arrngement with a filter and it would have forced cool air into the gearbox and then make an outlet for the hot air to come out with a suitable heat-resistant hose and going up high to prevent hot oil being siphoned out. The back-up plan was using a cheap 12 volt compressor to force cool air in