Hello everyone, I have been working on a project that some of you may find interesting. As you can see, my 2005 Civic had pretty sizable gaps between the sides of the radiator and the radiator support. There are several problems with having gaps around the radiator:
1. Air takes the path of least resistance. The path of least resistance isn't through my trans cooler, AC condenser and dual row radiator. Sealing those gaps helps force the air through the radiators rather than allowing it to go around.
2. When sitting in traffic with the fans on, some of the hot air that the fans push into the engine compartment can go through those gaps and get back in front of the radiators, reducing their effectiveness. With the gaps sealed, the fans will only pull cool air in through the grill and can't recirculate hot air from the engine compartment.
3. Any air that gets into the engine compartment pressurizes it. This is bad because higher pressure on the back of the radiator and fans inhibits airflow through the radiators, decreasing cooling capacity. Ideally the engine compartment would be under negative pressure but realistically that won't happen, so we want as close to zero pressure as possible for the best airflow.
4. Air flowing through the engine compartment creates drag and should be minimized where possible for the best efficiency. If air is flowing through the engine compartment it should be going to good use (cooling the radiators).
My solution was to cut pieces out of a sheet of aluminium that I have and use self tapping screws to secure it to the sides of the radiator support. To prevent vibration issues and rattles, I left a small gap between the aluminium plates I made and the sides of the radiator and covered that small gap with foil HVAC tape. I also sealed off some other random holes with that foil HVAC tape while I was in there. Easy, simple, and free
When I reinstall the bumper cover, I am also going to use a piece of foam to seal the upper grill to the top of the radiator so air can not go over the radiator.
Once I fabricate and install a shroud for my dual Spal radiator fans, I will be ready to put the bumper cover back on. But before I put the bumper cover back on, I am going to fabricate some ducting that extends from the radiator support to the inside of the bumper cover. This way all the air that goes through the grill openings will be forced through the radiators and can not go around and escape through the wheel wells, under the car, etc, which accomplishes nothing other than create drag. I know that probably doesn't make much sense, it will make more sense once I do it and upload pictures.
I am also planning on moving the radiator forwards about 1/2 of an inch so it is closer to the AC condenser and to give me a little more room to access the front of the engine. My understanding is that the radiator and AC condenser should be as close together as possible without touching for maximum cooling efficiency so the condenser doesn't deflect airflow around the radiator and so the radiator fans pull all their air through the condenser instead of being able to pull air around it.
I feel confident that all of these enhancements together (sealing the gaps around the radiator, installing ducting, and moving the radiator closer to the condenser) will result in a decent improvement in my cooling system's capacity, slightly better AC performance at idle, and a tiny decrease in aerodynamic drag. My intake air temp didn't increase either because I built a heat shield for my air filter to separate it from the rest of the engine compartment. As always, any thoughts or comments are always welcome and appreciated!
