I've seen trucks still belching smoke.
It must be that their max fuel flow rate is less restricted.
Similar to what our turbo cars could do if the IP rack limiter and alda were removed.

Most of these trucks also have manual transmissions, which means they can have very high fuel flow and high revs at the same time, which most of us don't do with automatics. The older trucks also have near no emissions controls, which means more particulate exhaust.

Our cars CAN belch heavy black smoke if they're not tuned well, or if someone unrestricts the fuel flow by the steps above. Why you'd want to, outside of a modest performance increase, I don't know. Black smoke=wasted fuel.

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