This is a simple clip of a police motorcycle starting and revving up a few times. It doesn't have much of a roar but is much softer of an engine sound.
Car idles, then revs for no other reason but to make a noise. Can't remember what type of car it was, but it was blue and little flames came out of the exhaust. Tascam dr-22wl, internal mics, deadcat. 15hz high pass filter.
This is a short clip of a chainsaw starting up, idling for a few seconds, then being revved up to cut a small log for a few more seconds before idling again. Contains idling and revving of a single-stroke engine. Recorded accidentally with an iphone in a pocket, so it's slightly muffled.
This is a toyota supra on a chassis dyno being revved to the max. It has a turbo on it and you can hear it whining. It gets extremely loud to the point of distortion, but it will be a great sound for somebody who needs an engine rev without the vehicle passing by.