The turbo helped the soot, the NA ones were really awful. Even turned up and turbo'ed they never got much over 2/3 the HP of the newer engines, lack of fuel, a turbo, and lack of emissions controls helped quite a bit in the soot generation. Downside was they wanted to overheat, melt down, fly apart, etc. Push a gen1 engine to 350 HP and the oil gets black really fast also, all about fuel and combustion.