What Is The Strongest Small Car Subwoffer Where Can I Buy A Compact Engine, Pretty Small, But Strong Enough To Make A Car Run At Normal Speeds?

Where can I buy a compact engine, pretty small, but strong enough to make a car run at normal speeds? - what is the strongest small car subwoffer

Regardless of the cylinders (at least 4 or higher) is not cheap, but are not as expenisive like them. Thank you.