Short answer . . . In the USA . . . MOSTLY NO.
Detailed answer . . . Federal Law prohibits tampering with emission control systems on emission control regulated engines . . . however on engines not regulated, usually those before 1974 then YES.
There are also some engines which have Exemption Executive Orders which would allow the use of it.
You could also apply for a waiver yourself if you are sure the manner in which it is used does not increase emissions in anyway, and if you are a franchisee we can help with that.
If you are an OEM manufacturer or re-manufacturer of the engine, you could create an engine family modification - and that is a complicated process, but we could also help with that.
Simply putting an older engine in a newer vehicle will not get around the law and and is unlawful.
On any device which is not regulated, that may not indeed be an engine strictly that uses Natural Gas or Propane, generally yes,
You need to read our terms of service and the links incorporated therein to understand more thoroughly. You could also join the company by purchasing a franchise and becoming active in pressing forward for success. See https://hydrogenpowercentral.com/great_investment_opportunity
I see Hydrogen products, can I use these on my car ?? See ALSO our TOS at https://bigbay4bestbuys.com/content/terms-service-andor-use