Thinking about filling in the gaps in front of the radiator. Seems like it would help prevent intake air from blowing out the gap and under the truck? Maybe it would work like a grill block by reducing the air going into the bumper by plugging the outlets?
From above you can see right through to the floor.
From below its a big gap just behind the lower bumper grill. I used to have the bumper grill blocked but took it out while testing a E-fan.
personaly i wouldn't do if but trying it as the best way to find out... on a dry day some card and tape is all you need.
one thing to considder is that any air comming trough the radiator is going to end up underneath the car anyway, unless it has other ways to exit like the wheel bays or bonnet vents, wich most cars don't have.
since the engine bay is an aerodynamic mess it's going to cause a massive obstruction to the air getting in there. wich has to find it's own way out to whatever holes and seems it can find. and end un underneath you car anyway.
personally i'd say backing these holes off may force more air trough the radiator wich perhaps might provide better cooling but very easily could have the opposite effect.
i'd say try to block of as much of the grill as possible but give the air that does come is an as easy exit as possible this would provide better airflow trough a restricted area and thus better cooling.
if you look as sportscars you'll often see that any air comming trough the radiator is provided with a smooth exit path trough dedicated vents.
Radiator stuffing...a good concept with a horrible name. I wasn't aware of this practice until Sam of STC put me onto it. In his own experience with his turbo SC2, he had noticed that the space between A/C condenser and the radiator allowed air to escape instead of being pushed through the radiator, thereby losing come of the cooling efficiency of the engine. In a creative burst of genius, Sam proceeded to stuff the cracks between the two heat exhangers until no air escaped. He noticed an increase in cooling efficiency when the fans were turned on. Sounds like a good idea to me. Up until Sam told me about radiator stuffing, I didn't know that the A/C condenser was in front of the radiator. I just figured that the thing I saw from in front of the car was the same thing I saw in the engine bay. Whoops. Anyway, first thing to do is to remove the 2 10mm bolts holding the radiator and A/C condenser to the front of the engine bay. The location of these bolts can be seen to the right. After these are removed, you'll be able to pull the radiator back towards the engine a couple inches and see down between the two heat exchangers. ...
I know some companies sell pieces of metal to block that same gap on the car, but on the top. I think if you blocked that hole off on the top and bottom, it would just make it so air from the front grilled goes directly through the radiator and out the gaps at the sides of your hood (if it doesnt have weatherstripping there, which from my experience, most don't). I can't see how this would hurt performance, but i can see how this would take away from the turbulence of the engine bay and maybe smooth out your airflow a bit.
I remember from a long while back, seeing some how-tos in Hot Rod magazine about blocking of those gaps your are talking about in order to increase flow through the radiator.
On the never-ending quest for better gas mileage...
Anyway, blocking or sealing the gaps between the items makes sense to me. That would make sure that all air going in the front item actually passes through all of them.
I'm not sure how much effect it would have, whether it's worth doing etc. - but the concept makes sense.
This would not harm the cooling process as it's encouraging more air to go through the rad, not less.
I see it differently.
Any air flow restriction in front of the engine's radiator will reduce air flow through the radiator. The fins of the A/C condenser aren't zero thickness so there is some wind-break effect and some radiator exposure area reduction. The air has to pass between the condenser fins. It doesn't pass through the metal of the fins. The fins, even edge on, do reduce the area of the radiator exposed to airflow by some amount.
Sealing the gap between the condenser edges and the radiator edges simply means that this gap isn't available as an air supply.
Sealing the gap WILL assure that the puller fan does move more air through the condenser, but it doesn't assure even the same amount of air through the radiator.
For what its worth I filled in that gap several weeks ago with colorplast. What did it do? Judging by the radiator outlet water temp it lowered the temp of the water so more air is flowing through the radiator. FE at low speed is the same but at high speed its a bit better by perhaps a few tenths, nothing dramatic though.
Now I have blocked off the upper most section of the grill, eh not that much of a difference...