Junk on the front...
 

Hi guys and gals. Been a while since I've been on, just been enjoying a pretty steady mid-30s mpg out of my wagon and haven't been doing much continuous modding.

My question is for aero impact of equipment hanging off the front end. I'm thinking of strapping an LED light bar to my front grill but wonder what kind of impact I could have. The Focus grill is set back a little from the very front of the car so the light bar could possibly catch wind that is coming up from the front and to ultimately pass over the hood. My upper grill where the bar would go is blocked 100% already. Would this catch air and add drag or is the front of the car so turbulent that it would be minimal? My other thought is center of the hood back by the windshield, driving in the snow seems that this is a dead spot and could work as a mounting location.

The bar is 21.5" long, 2 rows of 20 LEDs and about 4" deep.

Thanks,

You'll get a lot of glare coming off the bonnet if you mount near the windscreen.

I think you'd do better to paint the hood black and put the light-bar in front of the top of the windshield but below the top. For visibility.

At the front, there is a stagnation point where the air is trapped, then bleeds off to sides, top or bottom. Anything you put there will have negligible effect.

Here is the pic of the snow collection after driving through snow one morning years ago. I was happy to see all the collected snow in the grill making me think the block mounted behind it is working as I hoped. Looks to me like middle of the hood is dead air space between the wiper jets. Thoughts? Also gives an idea of where it would ride if I mounted it to the grill or on top of the bumper in front of the grill.

http://i.imgur.com/5nemKsU.jpg

You could make a pseudo light bar from a block of foamular or cardboard and test it out. ;)

I sat the bar on the hood and bumper tonight to get ideas. I'll need to cut up the grill to mount the light to the grill which isn't a deal breaker per se. Mounting to the bumper cover looks pretty good and wouldn't protrude past the very front of the car. I'm wondering if I stuff pipe insulation under the light if it would negate the extra drag of being mounted out front.
The stands ride perfectly to the outside of the washer nozzles on the hood, they hold the light about 1.5" above the mounting surface, I'm worried the bar might stick up too much above the hood and am thinking of making shorter brackets if I decide on the hood mount.

Anything on the front below and in front of the tops of the headlights will be inconsequential if it is faired in. Anything that size in front of the windshield will be inconsequential. My example, faired in Buick headlights in front of a flat windshield:

http://ecomodder.com/forum/member-fr...headlights.jpg

Not sure what your road rules are for aux lights in "Dirty Jersey" but here if they are higher than the headlights you need to keep them covered when on public roads (unless you are running a snow plow that obscures your headlights)

Also if you want the light for driving in snow you might find snow building up on the bar on the hood exactly when you want to use it. I would go for the grill.


I replaced the halogen bulbs in the headlamps on my Ridgeline with LEDs. I was concerned the whiter light would be glaring in falling snow but it has not been an issue at all.

That's surprising. I replaced the halogen bulbs in my Hella H-4s with LEDs and the beam pattern went all to hell-a.

I'd like to have the light bar for dark road driving and because it only cost me $30 lol. Since I can't see any bit of My hood from the driver's seat I don't think I'd even need to paint the hood black. I'll have to check the rules on needing it covered though as this is my first step into off road/ralley lighting and I'm not familiar with things at all.

Would love to fit one but uk laws ban them. Ideal for deer country wherw i live. Police up here have issued notices to anyone running any form of led. Side lights and marker lights included.

I have seen vehicles with two light bars and high beams around Flagstaff. From what I hear, if the highway patrol had any excuse to stop them, they would.

It doesn't seem that long ago that European headlights were illegal in 48 of the United States, excluding Oregon and Washington.

Xsit we traffic cops that clamp down with a heavy hand if you go to local court maxium penataly is appiled. No insurane means 12 ban car crushed and thousands of pounds in fines. Speeding is classified as dangerous driving which means minuim of 12 months inside. It to try and cut accidents down. Its usually a single vehicle accident well over the speed limit and death toll is very high. Came across one not pretty. Driver survived but person he hit didnot had to sit with him and phone to ambulance control. Had to describe injuries and try to keep him alive. Waited 2 hours for an ambulance to turn up. Dieing in car which has had an accident happen about once a month. Very little traffic use these roads due to low population denserty. This is way penalties are so sereve.

Well guys I finally got it mounted yesterday. Time will tell what/if it has any effect on my MPG.

Looks good, but it seems like it would add to your CD and knock your MPG down by 1 or so. :confused:

For why? Stick around and you'll find out about stagnation point and the beneficial effects of an upper grille block.

My [notional] money's on the mileage goes up.

https://www.cars.com/articles/those-...1420698369936/

"The results aren't entirely humbuggy: They found that a wreath on the grille doesn't cost you (unless the greenery is so extravagant that it blocks cooling air for the engine)."

I think and impact will be minimal. Once I get it aimed I think I’m going to pack foam under the bar to create a less textured front end. Not sure if trapping can happen under the bar as it approaches the blocked upper grill. Plus the plate attaches behind the grill and there is now a small crack between grill and bumper that is leaking air (I assume) and will need sealing of some sort.

minimal
 

You're probably placing it where it will do the least harm.
It's a full-separation structure,but the cars nose will be training behind its wake.Since the area around it is in the best pressure gradient on the car,the separation will be limited to only very close to the unit.
Walter Korff and Sighard Hoerner published Cds for shapes like this,but I don't have that with me here.:(

shape drag coefficient
 

In free air,the light bar would have a Cd of around 1.05.

Assuming it meets NJ DMV spec. I'd try some fine nylon screen mesh to fair into the grill. Test the pattern at night by observing the lights from another car head on.

Maybe I'm missing something, but wouldn't air go over the LED light bar and in through the still unblocked grille? And wouldn't it have the same effect as those headlights on older cars that popped up and caused unaerodynamic drag?

[QUOTE-aerohead]You're probably placing it where it will do the least harm.
It's a full-separation structure,but the cars nose will be training behind its wake.[/QUOTE]

What aerohead said, plus maybe a little grille block action due to interference drag and vena contracta.

Hm, maybe. Actual testing on this would probably clear up my confusion here. It seems to me to be a little counterintuitive, but I'll have to give way to you more experienced ecomodders. A grille block without the LED bar would still be better though for MPG, right?

I don't think your mileage will drop a bit with the LED bar in the grill where you placed it.

I have installed a pair of round LEDs in about the same position on my '15 Mazda3. In that position on my car, the grill is solid and is designed as a place for installing a front license plate where such a thing is required. Since my state does not call for a front plate, I filled that "void" with a pair of bright lights each containing 9 LEDs.

My two round LEDs naturally are not as long as your 21.5-inch bar, but they are a little "taller," being about 4.5 inches in diameter. The effect on MPGs, noise or anything else is nonexistent, or at least non-noticeable and non-measurable to me.

I've got a similar pair of these LEDs on the Jeep I use for off-road hunting, and they come in handy for that. But my Mazda doesn't go off-road, and since the LEDs are probably illegal on public roads and would certainly hinder oncoming drivers at night, about the only use for my extra LEDs are as signal lights and as very noticeable DRLs.

For example, yesterday I was passed by a "speeding" 18 wheeler, and since the traffic was tight and I knew he was anxious to get back into the lane, when he safely cleared my car I flashed the LEDs several times to signal him he was clear to return to his lane. He immediately pulled in, and to show his appreciation, he cycled his rear lights, which is a customary "thank you" signal in such situations.

I also use them to signal on-coming cars on two-way roads to let them know they are getting too close while passing another car, and for signalling pedestrians who seem too close to the road, etc. I could use the Mazda's headlights for such signal flashing, but the LEDs do it with a little more class; or at least, it's different. Hey, I got 'em already.

Occasionally, I also use the LEDs as daylight running lights (DRLs) in some threatening circumstances, such as in high traffic congestion with shadows when my little grey Mazda could easily disappear in the hustle. My car has small (about 2 inch) LEDs in the lower fog light positions as full-time DRLs, but they are not nearly as noticeable as the bigger 4 inchers in the grill.

I installed a button to press when I use the center-grill LEDs for flash-signalling, along with a toggle switch for keeping the LEDs on longer term, such as when using them as DRLs.

They do come in handy for such things.