so the engine mounted fan must suck cooling air thru the generator enclosure and push it thru the radiator.A duct louver is necessary to keep rain,insects and vermin out
but yet allow cooling air to enter,at the same time preventing a direct path for noise to travel..a duct inside will bounce the cooling air off the rear door yet to
be fabricated to stop transmission of noise outside..so far the Roxul rock wool absorber sheets are working out good..gotta wear a respirator cutting/working with it tho.
[Linked Image from kuhnbros.com]
The damn stainless meter box interfered with installing a full-length louver,i even tried moving it over a bit to allow clearance but it's not going any further because then the latches interfere.Oh well.

the duct louvers are from HVAC Premium,I can't find any better ones on the market, I used to build them myself but they didnt look right..there's a lot to them..this company makes them from heavy aluminum extrusions,
they will make them to your spec,I had one here that fit OK a little short but well within specs for airflow.
It rivets into the enclosure side panel which is removable with stainless flange bolts from the outside should it need to be.

[Linked Image from kuhnbros.com]

-Im building a air deflector/sound trap to mount to the duct louver inside the enclosure right now..pics later, Im on a lunch break,and its Saturday LOL

Ok so intake air deflector completed..time for a break..installed duct points towards interior rear of enclosure.
[Linked Image from kuhnbros.com]