The reason 1/8 scale moved to big bore was for consistency over long finals, as the oil would heat up and become thinner, changing the damping characteristics. Big bore means more oil, so it takes longer to heat up.
I'm not sure if there's any advantage in 1/10 scale, as you only race for 5 minutes anyway, which was never long enough for the oil to overheat, and the cars are comparitively lighter, and you have far smoother tracks.
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