To get a sense of the speed potential, you'll need to provide more information:
* What kind of engine is it? Is it a car engine, a boat engine, a motorcycle engine, or something else?
* What is the manufacturer and model of the engine? For example, a "VX 16" might refer to a specific Yamaha marine engine.
* What is the vehicle or application it's powering? The performance of an engine is highly dependent on the weight and aerodynamics of the vehicle it's powering.
Once you provide more details, I can try to give you a more accurate estimate of the possible speed.