I don't know anything about the engine you're talking about, but what you're describing sounds familiar, it sounds like the engine is detonating/pinging/knocking. This can be caused by running lean; I once had a turbo car with a faulty fuel pump which sounded like rocks going through the exhaust, of an ignition fault, perhaps the timing is off or some components are worn?
Either way, you're better off fixing it before going out in it again, or atleast shift up before it starts knocking, it's not good for your engine.
Either way, you're better off fixing it before going out in it again, or atleast shift up before it starts knocking, it's not good for your engine.
