Recently I did some modifications to one of my other Honda's (2000 Civic). I added thermally functional vents to the hood with integrated rain trays.
(viewable here https://honda-tech.com/forums/honda-.../#post52992449)

I was happy with how it went, so I said why not do it to my 2001 CRV?



Templates made from cardboard. These are the rain trays that will go under the openings that will get cut. They allow the water that will get in to drain in a safe area.



Once I have the right shape, I scan it into CAD to make a printable template that I can use to cut out sheetmetal

1 mm thick aluminum used on this project.

All bends were done by hand in a vise or in a break.





2 trays done. The drivers side has an extension to push the water further forward and over towards the passenger side away from the dipstick area.


removing the hood by myself

hood removed and ready for work in my paint booth.

testing the fit

Here I made a template for the cut area so they would be identical

Here you can see I cut holes and squared them out for clips that will be able to be screwed into.

cuts complete



test fitting the seal and looking at how much gap I have to the trays. This will be taken up by a "C" shape piece of perforated aluminum bent specifically to fit the space right.

I made a paper template from CAD to cut the "C" shape piece.

the C shape piece will attach to the rain tray. This way everything is installed at once.


Here I sandblasted and poweder coated the trays.

Trays installed.

 

Looks good, lots of effort! The grill choice painted black is tasteful.

One thing I might add, if you added a raised leading edge to the vent, at speed, air will be deflected over the vent, causing some low pressure that will suck air out of the hood thru the vent.

 

Thank you. I did my own powdercoating with flat-black with the harbor freight tool. Based on what I find with my civic, I believe this will already happen on the CRV given the location I put these. I did tuft testing on the civic and you can see the tufts angle away, meaning the underhood high pressure area is pushing out of the vent.