I am running full width axles. No inner fenders, just the outer fenders and hood. The tires DO throw a lot of water!
As I mentioned, I've watched when I hit the mud holes and for the most part I'm only concerned with the engine bay water. It seems to all get deflected off the hood/outer fenders and comes INWARDS towards the carb. I've watched the wave sweep over the engine, surround the K&N, and snuff it out.
At the same time, very litte/none came OVER the hood and onto the filter - all of it came from the engine bay and came UP.
If I were running the double-stacked 10x3 (so.. 10x6) air filters the original owner ran (thus the hood hole), the second air filter would be almost fully outside of the hood.
Thus, a 5" "lift" on the air filter housing would definitely put it over the top of the hood. 8" would assure it (like the K&N velocity stacks). I would build a full "hood scoop" with a rear opening to cover up the air filter which would keep any splash from the front or sides that makes it over the hood from coming into the filter. The only patch for water to get in would be from the rear, and since there isn't a windshield to send the spray back at the scoop, and I don't plan on going *backwards* through the water.. I think it'd be alright.
The firewall "snorkel" is also very appealing - I KNOW it'll work, too. My only concern is getting a good fit to the air horn, and making sure whatever material I choose will be large enough to flow the air I need. It *is* a "small" displacement IH 304V8, but it has a bad thirst for air/fuel. I had a 350cfm 2bbl on it at first and I had a rev-limiter at 4000rpm. It couldn't suck enough air in. With the 500cfm I'm pulling 5000rpm at the end of the drags, and I still think it needs more. Might just be I need to jet up again, maybe I need to retard the timing a tad.. could be the air filter or a number of things. The motor is only 7 months old and barely broken in.. and gets thirstier every pass. I'm looking for a bit over 6000rpm out of it. 350hp/400lbs-ft from my little dump truck IH 304.
If I would stop shredding the suspension, I might actually get back to some dialing in on the engine (at the last race I S-ed the springs in the drags, then tried to end-o the truck in the obstacle race.. just finished fixing *that* mess.. )
How large of ducting do you use to feed your 440? Any signs of it choking it off at high RPM?
If I had a factory enclosed filter housing lying around to use I might be more inclined to try something different (heck, that would solve a lot of the problem right there).. but I don't. They're all in use.. and if I'm going to *BUY* a new filter housing, might as well look n' see if there's a better solution first.
I'm still leaning towards the velocity stack. If I can get the filter up out of the water *AND* improve engine efficiency at the same time.. how can that be all-bad? ;-)