Sailorman,
Have you looked at dust collection hoods as used in woodshops. Four inch is a standard tubing size and they come in various shapes.
I rejected that option early in the development.
I first considered what environment the air ram had to contend with:
High temperature near 212° or above limited by phase change for pressurized steam
Presence of various forms of petroleum
Physical considerations:
Elevated air pressure from air speeds 80 to 100 mph
Negative suction air pressure from Rocket 455
Presence on liquid water at speed from rain or spray
Humidity levels
Dust
Insects
Vibration from motorhome driving on road
Impact shock from vehicular movement
Exterior wind speed
Variable exterior air temperature
Apart from dust, which in the shop is probably sawdust, a shop vacuum is not designed for most conditions, although it may handle liquid water.
The fuel funnel seemed to more closely fit the bill:
Capable of dealing with petroleum (gasoline & diesel)
Physically stronger to deal with liquid gasoline or diesel rather than gaseous air
(Probably will handle higher air pressure from vehicular speed)
(Also deals with the impact from a gas can or gravity from an elevated fuel release)
UV resistance unknown
Physically designed to concentrate liquid from a large inlet to a small outlet
(good for air compression)
Compatibility with adhesive bond unknown.
Then there is the deck plate ring:
Good for a salt water and spray enviorment
UV stable
Waterproof
Solar generated heat
Can be fitted with a 4" dia. hose
Compatibility with adhesive bond known to be OK.
Not bad but not good enough. What is better? An exhaust fitting for a clothes dryer:
Built for petroleum fumes because the dryer may use natural gas or lpg.
(Exposure to unburned petroleum but better than than from the 455)
Built for high temperature
(likely higher than steam temperature)
Air is blown not sucked
Physical strength should be ok to prevent fracture when dryer is bring moved into position.
Compatibility with adhesive bond unknown.
Filter Requirements (selection not finalized):
Need appropriate physical size to be used to fit, added and/or replaced.
Need appropriate filtration level.
Need structural capacity to handle pressure from vehicle speed, air ram pressure increase and possible
turbo or supercharger suction
Need structural capacity to handle insect or particulate at speed
There is also the potential failure from issues not foreseen during actual use.
So far, I think that I am on the right path but I am not ready for installation.
