The mist you see is "adi fluid" that is sprayed on oil coolers but some planes use a "boil off" scheme.
The box behind the engine is where the air/water intercooler normally sits with the curved casting you can barely see below and behind it being the supercharger itself.
Most, if not all reno planes are now "pipe engines" in that the intercoolers are replaced with a pipe and they use alcohol/water (adi fluid) to cool the intake charge.
The proper term is really "aftercooler" especially in two stage systems that use a water cooled shroud around the supercharger which would actually be the "intercooler" but, if you use the wrong terminology enough times, it becomes accepted as correct much like the term "NOS" which people now use instead of N20 or "nitrous oxide".