[QUOTE=brucepick;57519]My take is, it's both aero and cooling.
Any air that skips over the hood or is pushed cleanly to the side is better than having it bang around in the engine compartment and under the car. That's the aero improvement. For that to work optimally, you want a nice smooth surface at the front of the grill so the air can slide off cleanly. But even blocking it behind the grill is better than letting it get in, as far as aero goes.
Very true about bouncing around the engine compartment. In the geo the rad. is off set also. Grill on right side will be blocked. At the same time two panels at the right and left of the rad. will be installed to guide it through just the rad. Under the hood between the grill and rad. core support. Plus the belly pan will act as the bottom of the trap. This hasn't been proved by me yet but I THINK you could get away with a smaller opening if you make sure to maximize the flow. If you have an actual temp. gauge go bold and have something with you to cut away material if you need to. Don't let it overheat all the FE in the world won't pay for a cracked head or two!
I started to do my mod today. I took Gary's advice and removed the plastic covering the radiator. Then I said the hell with it and removed the plastic grill. I think it will be easier to size the whole project with the grill out. I was considering leaving the grill out and making the block flush, but I don't think I'm that good at making things. I'm also considered using foam between the grill fins. I took some pics to get some opinons.
i think there is an aftermarket company that makes grill blocks? I've seen them on f-150s ,rangers. I'm not sure who makes them , they come in different colors and they have small holes in them to get some air flow to the radiator. I would probably get a cooler thermostat installed to compensate for the lower air flow on the radiator.
Lund is one company they offer a bunch of grill blocks, i was looking at the plastic inserts one with holes, the other is a winter block with no holes. http://accessory-center.com/Plastic-...ront.1423.stml
Are those grill intakes below the bumper? If so, then the lower openings should be more than enough to handle your cooling needs and you can totally block off your upper grill openings (trim Coroplast to fit and secure with screws, velcro, or clear caulk).
The upper grill openings on most cars is mostly a concession to styling (people traditionally expect a car to have a grill, so the stylists give them one), but they are not really needed for cooling. Compare the grill openings of the new Beetle (mimicking a grill-less rear engined, air-cooled car) and the Golf or Jetta. All three cars have the same ICE and radiator, just different sized grill openings. Ditto the 92-95 Civic and the 96-98 Civic. The earlier generation Civic was optimized for FE and just had a grill opening below the bumper. On the later generation Civic, the stylists had their way and they added a chromed grill intake above the bumper (the highway EPA mileage dropped from 46mpg on the 92-95 to 37mpg on the 96-99 as factors other than maximum FE came to the fore).
The bottom is a grill intake. I was thinking about putting the coroplast behind the grill fins, or do you think I should do it with out them? I'm gonna talk to a body shop tommorrow (across the street) and see what they recommend. I really don't want to mount using screws but clear caulk sounds good. Would the cock ruin the paint? Also what do you think a body shop would charge to close up the grill using fiber glass or whatever else they use?
You could take the world famous test material cardoboardo and use some plastic wireties, to tie it to the grill from the back side. If you threw some econo black spray paint on it, before you attached it, it probably would be almost invisible. The holes in the bumper do allow air flow and they probably would be adequate for driving.
I started working on my grill block today. I decided that I would use coroplast behind the grill fins. Having the grill fins would make it easier to mound and would be sturdier. This wasn't my first choice but it seems to be the best way (to me). I also tried using foam in between the grill fins but I didn't like the way it was looking (maybe in the future). I haven't completed it yet because the spray paint is drying. I decided to skip the black paint and go with red (wanted to be differenet). My only question is how should I mount it? I bought zip ties and some epoxy stuff designed for plastic.