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Just picked up my cylinder heads from the machine shop to have them decked. Ended up taking 0.020" off of them to bring the combustion chambers back down to 48.5cc. I wanted to show my son why you would want to use a non-turbo plug in a combustion chamber that has had the plug boss removed, but he informed me that he uses search and re-search frequently and this was not news to him. I grabbed a few pics.
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You can see the chamber on the left has an NA plug in it and it does not protrude beyond the combustion chamber roof. When the valves open up and the air begins moving, it can smoothly flow out of the intake valves and not hit the obstruction of the plug and boss. The plug in this case is a very small obstruction. On the cylinder at the right, there is a TT plug installed and you can see how bulky this becomes and how it can affect airflow into the cylinder. Keep in mind, at 6000RPM these valves are opening 50 times a second so there is very short time for the air to enter. Obstructions like a fat plug body make a difference worth addressing.
Additionally, the deshrouding can be seen between the valve edge and the chamber periphery. If you look closely, you can also see that I have radiused the ridge that forms the 'squish' area (these are the flat-sides of the chamber).
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Since the shorter plug puts the spark at the top of the combustion chamber, the propogation of the flame front in the chamber can only go downward. This reduces the amount of energy lost to heating the parts of the chamber and keeps it within the gases to promote pressure, which means more power.
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And lastly, the polishing of the chamber makes the material more 'reflective', not only to the visible light our eyes can see, but also to other frequencies of energy, namely heat. Keeping the heat in the gas and away from the solid parts of the engine means better efficiency.
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Please, no comments on the underwear, LOL.
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[ agpowers@bellsouth.net ] Enthusiasts soon understand each other. --W. Irving.
Are you an enthusiast? If you are out to describe the truth, leave elegance to the tailor.
Albert Einstein
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Even my 3-year old son knows proper plug selection. >> - 
15:40:46 11/24/04
