Oh sure, i don’t doubt that. You can build super engines on everything. But we are talking about converting existing passenger engines into running on it. Thats not so good. And dragsters only go 1/4 mile. CNG cars have extremely short range.
Our city bought them for the police in some PC grant program. Within a year they were being used by cops that worked inside schools all day and didnt need any range, and other assorted city workers that didnt drive much except maybe one short trip a day.
LPG is better than NG for energy density. Some cars were gas/LPG bi-fuel.