The phrase "heavy knock" is correct and usable in written English.
You might use it to describe a sound, for example: "The door shook from the heavy knock."
A heavy knock shuddered through the door.
"He took a heavy knock to the knee, so it's swollen up quite lot.
Heavy knock was deliberately induced by adopting inlet air heating and a primary reference fuel blend of reduced octane rating.
It was a big knock, a heavy knock in his leg, but we hope it's not a big problem for the next week".
"Matty got a heavy knock on his shin in training so will be out for a couple of weeks," Pearson continued.
The Power suffered a nervous moment when Schulz banged his head on the turf just a week after copping a heavy knock to the face.
"When that engine is cooking along," he said, "you get these heavy knock-on effects".
A heavy knocking on the door.
There were heavy knocks also for Nathan Sharpe (leg) and Brendan Cannon (shoulder).
Overall, the results demonstrate the risks in employing excess fuel to suppress knock deep within a heavy knocking combustion regime (potentially including a Super-Knock regime).
He chased everything, took some heavy knocks from Laurent Koscielny and Hector Bellerin, winning Liverpool's penalty.
