340 kph is around 211 mph I think. Pretty quick. This was likely an earlier attempt at the 'unlimited' FAI record www.youtube.com/watch?v=u0MN6NHChZI The older AMA D speed which was a .65 cu in. limit was hitting 200 mph when I was a teenager. Nitro was allowed as well as a pipe. As soon as 200 mph was hit, the pipe was banned. Then it hit 200 again, and 10% fuel was the new rule. A piped .61 would be fun to try on nitro again especially if you could use a thin monoline. There are surely better motors now than in the 1970's. I would want some control when going fast. The planes oscillate with any breeze and the planes hit hard at over 150 mph, been there done that. The parts scatter.