The Valentine mini single engine (far left engine in photo) was designed and built by Ronald Valentine, of FL. In the 1980s, Ronald, who is known for his miniature diesel engines, designed and built three miniature four-cycle model airplane engines. Two are air-cooled single-cylinder model aircraft engines and one is a 5-cylinder radial engine measuring only 3.25 inches in diameter. All were designed to burn methanol on glow ignition, and all required special (custom made) glow plugs that Ronald designed and fabricated. These are the only four-cycle model engines built by Mr. Valentine.