So I read that if I put a front grill on the car, such as from Coastal Metals, the car will heat up quite a bit more. Any thoughts on this? And is there a grill you would recommend?

 

Although I've never done temperature readings, mine has never climbed above 3 bars even on 90+ degree days sitting in traffic. I do have my fake vents cut out though.

 

A grill has proven to cause higher coolant temps in high ambient temp, high load conditions. If you choose to use one you should keep an eye on the temp gauge if it is hot out, you are pushing hard, or driving at higher altitudes.

 

I've never had any issues with mine - never tracked the car but I don't baby her either. Cannot begin to guess how many insects have been denied access to the cooling fins on the radiator but from the (seemingly constant) looks of the grill there is no lack of trying on their part. Sometimes the aftermath of the slaughter is quite sickening.

 

For daily driven cars in most climates, the grills should pose no problem. I had mine on the car through two 90 degree east coast summers before moving out here and never saw an increase in indicated temps.

However, after moving out west and tracking the car in the middle of the high-desert in mid-summer, I saw 4 bars on the temp gauge on more than one occasion. Removed the grill and the problem went away, so it's really a matter of how you drive the car at high ambient temps. I do miss seeing all those dead bugs on the grille and not in my a/c condensor though

 

The grills typically have no more than 60% open space, so the answer should be obvious - yes, they do reduce airflow.

I would agree that for most driving, there is enough reserve in the cooling system to absorb this reduction in cooling efficiency - however, I do not find it convincing that the temp bars have not shown an increase. Beyond the normal (3 bars on 00-03, 8 bars on 2004) area, Honda gauge are calibrated to be non-linear; that il,k it takes a big bump in temps to get the gauge to move at all. This is done because car nitwits do not understand linear gauges, and bombard their dealers with "concerns".

At high speed, there will be an increase in drag as well.

My problem with the grill covers (other than I do not find them attractive*) is that who knows what the line is between OK and trouble? Or the line between optimum performance and a dial-back in spark advance because the ECXU does not like the higher underhood temps.

Some peeps argue that the loss in cooling from lots of bugs/leaves in the grill is equally risky - but that would be a lot of bugs, and some terrible ongoing maintenance by the driver. I routinely wash/spray the radiator, as do most owners.

*They make the S2000, and especially the Miata, look like a "foil" electric razor.