rev up vs rev

rev up is not a noun while rev is a noun.

Word	Noun	Adjective	Verb	Adverb
rev up	No	No	Yes	No
rev	Yes	No	Yes	No

As verbs, rev up and rev are synonyms defined as:

rev up (noun)	rev (noun)
	rate of revolution of a motor

rev up (verb)	rev (verb)
increase the number of rotations per minute	increase the number of rotations per minute
speed up