93-95 front bumper - achieve better airflow?
 

I was reading through some threads on AI and happend to click through a long string of links where I came upon a short discussion on the 93-95 front bumper. Obviously Mazda changed the bumper for a number of reasons airflow and cooling being two of them. But, this thread unlocked a thought i had in my mind as I was changing the oil the other day.

Why in the heck are their two half moon plastice pieces (similar to the block off piece on the non R1/R2 models for the second Oil Cooler) restricting airflow through the front of the bumper in the open mouth. I read (in this kevin bacon game link clicking mess I went through) that supposedly cars WITHOUT fog lights had these plastic "half moon" pieces and those WITH fog lights did not.

Now the previous owner to me had purchased and installed the factory fog lights (including the switch) onto the 94 PEP I currently own. So I am wondering, do I have a triple whammy in poor restrictive airflow due to these "half moons" and the fogs lights and the 94 bumper?

Perhaps someone can shed some light.

-D

A shot of what I am talking about
 

here is a quick shot about what I mean. I am half thinking I should remove thise pieces.

This picture is the driver side front part of the opening:

http://i535.photobucket.com/albums/e...4/DSC00439.jpg

haha i believe so. you can remove the half moon pieces without taking off the bumper. you might have to remove the fog lights to get to them though

Actually the R1/R2 models also had/have them and were slightly larger. Currently my R1 is sporting the smaller (touring) versions but w/o fog lights.
Others have removed them and IIRC some who track regularly even have installed a vertical brace to increase inlet area more.

Are they used to help trap air or something, mazda had to put them in for a reason

Thats what I am trying to figure out. I haven't removed the under tray as of yet to really get a good look, but as far as I can tell, the M2 CAI airbox intake (the one that pulls from the side of the radiator) I have is being blocked by these plastic pieces on the passenger side.

Other than cosmetics, I can only speculate at their purpose. At any rate, I doubt it's interferring with you CAI.

Grodon,
What you speak of is the Shark Mouth mod for the bumper ( I think it looks cool), but I am curious if you or any one else has ever removed these plastic pieces on the side. Anything I can do for better airflow I will try ( and I am thinking I may do some testing this weekend to see if it is a positive or negative effect). It was the N-Tech shark mouth mod thread where I first read about 'removing the half moons' for better airflow. But, in the same thread I see people discussing about not filling the holes around the radiator causes WORSE cooling. Of course this makes sense. Before I start spending time on fabbing a better induction path I wanted to better understand the reason why MAZDA put these things in.

I believe I can pop these little things out without removing the bumper so I amy take the car for a couple of test runs this weekend with them in and out.

u think you will be able to measure this in any way shape or form?

That's an interesting topic. I have the same thing on my car minus the fog lamps! I too was thinking of removing those plastic things as they look like they are restricting the air flow more than anything else! And my right side vent is also blocked off too with another piece of plastic!

+1 to removing the fog lamps and plastic ears behind them. Takes less than 5 mins, the plastic ears slide off. Temps dropped 5* when cruisin around.

Really? Mine remained essentially unchanged. As I recall, it actually ran about 1 C. (on PFC) hotter without them...but I didn't consider that significant.

To dfoster154.......
FWIW, the picture you posted doesn't appear to be of a factory fog light. And the accompaning trim appears to be that of a R1/R2model, which is larger.

I know it's risky since I have no formal training in such things, but MAZDA made two different sizes of those trim pieces (depending on whether or not you have fog lights), so my suspicion is that there is a purpose to them. Maybe to focus air flow and/or to increase velocity at certain speeds onto the face of the condensor/radiator for better penetration?

I suspect that the plastic inserts are to increase the face velocity (and focus air pressure) onto the radiator surface. If there are any openings around the radiator with these guys removed, it will severely short-circuit the airflow to the radiator.

Guys thanks for your input. I was going to give the FD a quick test with them in and out today, but bad weather coming in this evening has me looking at this tomorrow perhaps. I know measuring will be difficult, and I agree they SHOULD help force more air into the radiator.

Sgtblue, You are again correct, and I was mistaken on the fog lights. I just went back to the documentation from the previous owner... The Foglight Switch is Mazda OEM... the foglights are by Blazer International or something like that. They look good so thats all that matters i guess :)

Now the fact I have these after market pieces makes me think. that perhaps the foglights are causing a negative pressure just behind them due to kicking the air out towards these half moons... In either case. I crawled under the car and these things are SIMPLE to pop out an put back in, so I am going to give it a whirl and see what I get.

One other quick note, my car is a 94 PEP. It has the R1 lip on as well, but the front bumper is the standard 94 cover that came without lights.

BTW, My cooling temps are actually pretty good, I have just noticed that when it gets soaked while in traffic from time to time, it take a good while of open driving for water temps to get back under 90. In traffic (which doesn't happen often - this car is NOT my daily) it will usually run 94-97. I guess when I am under my car my mind runs...
Again thx for the help, and I will let you know if I get a chance to test this out.

Here's a pict of the ones I removed from my R1, complete with overspray. I buy into the idea that these prevent air flowing around the gaps on the sides of the radiator.

The side pieces do increase intake velocity some by forceing some side air into intake opening; but also reduce total amount of air "Q" flowing in; area x velocity. I removed mine but I alos carefully sealed all gaps around radiator.

I think Mazda used the pieces to cheaply move air flow away from the gaps, filling gaps requires tighter tolerances and or human intervention on assembly line .. too expensive.

If increaseing area thus reducing velocity was a problem then the shark nose and 99 bumpers would be counter productive But they are not... they do help!

^Good point. I also filled gaps with dense upholstery foam, but left the (small) deflectors in.

Where would the air resistance...from the condensor, radiator, fan assembly, and (at times) over-pressure under the hood come into play in the equation? And also at lower speeds typically seen on the street but not track?

I'm leaving mine in the bumper, especially with Sgtblue confirming what I speculated might happen.

So after taking them out, I must say Sgtblue is probably right. I saw really no difference between the two setups in the runs I made with them on and off, although it seemed in traffic my temps climbed a little faster with them REMOVED. (I wish I had equipment to better define test criteria, but oh well.)

My radiator had no gap filler on the ends so I am sure that is part of what I saw. I guess from this expirience, leave 'em in and try the Shark Mouth Mod...

I removed mine and the fog lights. I personally think that fog lights cheapen the look of the fd so that was one of the first things to get removed from my car. I just did a little ducting for my v-mount but still have tons of gaps and adjusted my fan temps with datalogit and I never see high temps in socal. If you have a half way decent cooling system i dont see any need to keep them..

Great thread Thx I was just wondering this myself. Livining in Florida I thought I should do anything I can to combat the enemy HEAT.

I was also wondering if anyone made some after market pieces that would run straight back to the radiator thus channeling the air into the radiator?

Cheers

I agree with this theory. For what it is worth I have pulled two birds out of the area just around the plastic inserts. R2 with no fog lights - I hit one at maybe 45 mph. Seems like the air is forced into the slant of the front end.

Ok guys. here is how it works. Take a look at a couple of things here. Look at any intercooler duct. What do you notice. The inlet is smaller than the outlet. Oil cooler duct. Smaller inlet bigger outlet. Now think about what that hole in the front of your bumper is. Its an inlet. For what? For your radiator. You should never see a temperature drop from taking those pieces out unless you have a malfunctioning cooling system. That is not how a cooling system works. The principal here is this. You want the inlet opening to be smaller so that at speed air is actually being pulled through the opening. Think about it like this. We are dealing with pressures here. So at a light gust of wind sure no problem all the air will get through say the oil cooler. But as you increase velocity you increase wind speed. Now you have a higher pressure of air being exposed to the front of the cooler. If you want the air to pass through the cooler you need that pressure to be lower. You achieve this by reducing the amount of air that can get to the front side of the cooler. The ideal is to make a venturi so that the air is actually being pulled through the cooler. If you think you know better than the millions that mazda spends on r&d and wind tunnel testing and the scientists that come up with the results that deem little plastic guards necessary then be my guest and take them off. Chances are, mazda didnt spend time producing weird little plastic trinkets to change the hole size in the front bumper for no reason. Look at it like this.

Mazda guy 1, "man this bumper looks way better with a little bit bigger hole in the front"

Mazda guy 2, "yeah your right but the hole's area is too big for a proper venturi effect for the radiator.

Mazda guy 1, "ok how about we make the hole bigger and then change the inside area with little plastic things"

Mazda guy 2, "well done good sir, now we have perfect ventui effect and great airflow as well as a wonderfull look. Truly win win."

You, "dur hyuck, i tink dem thingys makin tha hole smaller make it cool less goodly, i'ma gonna take dem out. Oh lookey my needle looks lower i'll say 5 degrebs lower, eberybody should do dis."

Sorry, but that's not really correct. The venturi effect is not the mechanism creating flow across the heat exchangers. A venturi is just a reduction in cross sectional area in a duct flowing a fluid. Area decreases, velocity at that point increases and pressure decreases at that point.

Venturis don't pull anything through them, they restrict flow. So, to have a venturi, you need a pump or equivalent creating pressure at the inlet. You're thinking of a venturi's use in an application like a carburetor where fuel is pulled into the fluid air stream via venturi effect.

I'd imagine that the mechanism for flow here is just a difference in pressure. High at the nose of the vehicle and low behind the heat exchanger. My guess as to why these things exist is to create a higher velocity/flow rate at lower vehicle speeds.