We Americans now use metric for engine displacement. If I were to guess why then the engineers insisted.

If the design is old enough it'll sometimes be referred to by it's cubic inch displacement. But, even then the terms seem to have been replaced. For example, a Chevy 350 is now more commonly referred to as a Chevy small block.

650 cubic inches is about 10L. For reference, here's a ridiculous picture of a Chevy small block (~6.0L) on a motorcycle, called a "boss hog".