How to unlock hidden horsepower

How do mechanics make sure an engine valve is perfectly sealed?! ⚙️🏎️
If your engine valves don't seal perfectly against the cylinder head, your engine will leak compression and lose a massive amount of horsepower! To fix this, mechanics use an old-school process called "valve lapping."
They take a special, gritty abrasive paste called lapping compound and smear it around the edges of the metal valve. Then, they drop the valve into the engine block and use a wooden stick with a rubber suction cup on the end to rapidly spin the valve back and forth against the metal seat! The gritty paste acts like liquid sandpaper, physically grinding the two pieces of metal until they match perfectly, creating a 100% airtight seal!