What is this grill thing and do I need it?
 

My FD has a knightsports V-mount and I'm looking at this stock grill opening.

There is a plastic grill support that constricts the grill opening. I know japanese engineers are smarter than me so I'm assuming they are there to create some sort of aerodynamic eddy to encourage airflow but now that I'm not stock do I need this or can I cut it away?

Also, does anybody know where I can get one of those little black tabs? I'm missing one.

thx.

I asked the same question about the black plastic half moons some time ago and found a considerable amount of debate about the topic.

After experimenting a bit I noticed better low speed (45 MPH) cooling with them off. I'm guessing that they were put in place to aid MPG on the highway and not cooling.

I've had them off for six months without any issues.

Ray and Malloy can get you the tabs.

do you have any pictures of how it looks without those half moons?

I've been debating removing them from my car for better airflow. Currently my half moons just eat bugs on the highway.

Where do I find Ray and Malloy?

Search Malloy Mazda. Ray is the Parts Manager and an FD owner himself. Great track record as a parts source whereever you are. He'll know what you need.

I left mine on because they support the edge of the bumper. I did trim over 50% of the off to improve airflow. The FD, pre 99 has such a small opening in the front.

For best cooling they should be removed, but then you will also have to make some blocking plates for the sides and side bottoms where air will escape and not flow backwards to where you want it to go.

Yep ... search for Ray's info. He's the best when it comes to OEM parts.

Here's a few more pics ...

removing them makes logical sense to me, but why would they be there in the first place? Is there an aerodynamic principle at work that I'd be messing up by altering that hole?

Looking a James Paventi's pics I wonder if it was just an aesthetic mod in order to cover up the ac lines and give the car a cleaner look. It may just be that simple. lol

I don't have a science background, but concerning air to the radiator, it seems like volumn and velocity should both be considered. Those side 'ears' probably serve the latter and may help get it through the condensor and/or over-come high-pressure in the engine bay. Anyone have any hard data comparisons with and without, and at different speeds?

Our '94 was bought new in Sept. '94 and does not have those air blockers.

Didn't PEP/PEG models come with fog lights?

I guess i'll be cutting mine out next time I work in the front bumper area. My 93 is touring but i've removed my fog lights long ago.

The half moons are removable by sliding them off of some metal mount points. Unless you feel a need to leave a portion of them behind sliding them off is clean, easy and leave the option of re-installing them.

Love to see it too. The only think that I know for sure is that at the same temp, same day, 45MPH, same stretch of road the car went from 190f with the half moons to 185f without them.

One other thing to consider in the quest for better cooling. Check around the radiator edges (hood shut, A/C on, reaching in the front opening) with your fingers when the fans are running. I've found several spots where the fans blow hot air back out to the front and recirculate it. I've blocked all of this off to force hot air to exit out the back. This helps the temps stay around 210f when the A/C on, heavy traffic and a 105f outside temp. Before this I would approach 225f. Mods are in my sig link but the notable ones here are a Fluidyne radiator, FC thermoswitch and PFC set with fans to come on at 200f.

I still don't get this, I am confused. What exactly do they do?

No one is absolutely sure. We're all speculating. But Mazda made two sizes of them...one for fog lights and a larger set for cars with no fog lights.

I think that there are three sizes:

small - fog lights
medium - non-fog single oil cooler
large - non-fog dual oil cooler

Has anyone noticed? I may have to put a check for this on the to-do list at SevenStock this September. It would at lease add evidence that there is an impact on cooling.

Our '94 did not. Nor is there an unused switch in the cabin. Car was built in November '93, has electric metal sunroof and leather seats, but no fog lights.

Presumably they prevent incoming air from flowing around the A/C condenser/radiator group, which increases air pressure in front of and thus airflow through that group.

Too much credit is given to Mazda engineers as if they did everything 100% correct. They did a great job but not excellant with the FD. That is why today we can make 350-400 whp and the car is so much more reliable than it was stock with 225whp.

They did do a great job, but I don't think they did everything correct, nor am I giving them "too much credit". I tend to believe that there was an engineering purpose behind those ears, in not one but two sizes. And speculated on some possible purposes. If those engineers could have made the bean-counters happy by deleting them why didn't they? If some one has some data I'd be happy to change that opinion though.
I don't see your point. They were dealing with CAFE/CARB and host of other restrictions while trying to make a profit on a high-performance and relatively low-production car that dealerships were going to have to service. MAZDA didn't produce this car as a hobby.

well, Ima go ahead and remove them and see what happens.

Pretty sure they were merely there to cover up the area where the fog lights would normally go.