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BobBonahoom

Ceramic Head Buttons?

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Has anyone ever tried machining a head button out of a machinable ceramic material like macor?  I wonder if its thermal insulating properties would make the combustion process more efficient?  Also, it may then be easy to sputter a thin film of Pt/Ir onto the ceramic dome, which may be catalytic to methanol because of the heat retention.  In other words, the button becomes a sort of giant glow plug and you get a more even and efficient burn.  This sounds a bit looney, but just wondering.   I was remembering when people were running engines with 3 glow plugs and just started wondering.  Thoughts?

Macor 1.PNG

Macor 2.PNG

Macor 3.PNG

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Bob,

We are working on a ceramic coating system for head buttons,

piston crowns, and pipe surfaces. I will be testing it at Blue Lake in February

on a few new motors.

Happy New Year,

Mark Sholund

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Here is a reply from Brian Callahan.

No idea about the catalyst coating, but I do have experience with thermal resistant coatings. Not exactly the same thing as a whole head made of insulating material but close.

Most people fail to think about the compression stroke. Heat saved by the insulator during expansion makes the chamber hotter and the gas to compress also hotter. This drops density which reduces trapped charge mass. In turn power and torque are reduced. Compared to the extra expansion work achieved on the downstroke, there is a small net loss.

Also detonation is aggravated. This means lower compression ratio or higher octane fuel (less nitro) would be required. Both hurt power and torque.

Toyota and a lot of OEMs studied this concept to death in the 80s. The overwhelming consensus is that the concept is fundamentally flawed. I would not waste any time on it.

 

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As I pointed out in another post, you want to transfer heat out of the combustion chamber in the squish area but not out of the dome area.  You can do this to some degree with head shape.  You direct cooling water over the squish but not over the dome.  Plug cooling is important as well so a pee hole directed at the plug would work.

I've thought about Zirconium as an engine material.  It's very common in dentistry and the technology to accurately make small parts exists in all modern dental labs.

Lohring Miller

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Dose some one have the figures for thermal transfer of different metals?

I am not seeing trapping of heat in the chamber as dropping the density enough in are small eng to make a difference.

Now having the chamber hot to flash off the Nitro I can see being a +.

Also the squash being cooled down so it is not a tight hot spot for detonation to occur.

Also it will remove heat from the piston. on the outer edge where  is thinnest at the 90 deg corner.

I stopped testing before I tried Ductile iron for a head button.

Would be nice to see some one give it a good try.

I have a feeling if made right it could do all the above .

I will get back to it one day and give it the old Collage try...........................LOL

 

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