I have an attachment for my engine design. It says top torus, but they are both half spheres or half hemispheres. It seems counterintuitive, but the explosion at the base of the closed cylinder doesn't just blow past the cylinders, but pushes them apart.
The x's lining just below the cylinders as well as the shape of the hemispherical cylinders drives a pure flame as opposed to the usual combustion in a cylinder of dispersed cloud. It appears that the engine would be opposed force because the pistons are moving left and right, instead of up and down? That's my question.
The top of the cylinder is open to the atmosphere, and the flame disintegrates to a string there.

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