Quote:
Originally Posted by nalc
I have a question about HIDs in stock housing... forgive me if it's retarded, but:
The issue with HIDs in stocks is that they aim too high, and shoot up too much glare... you can see fine with them, but other drivers will be blinded. That's why HID projectors have a cutoff shield.
Now, what if you were to drop HIDs in the stock reflector housings, but then put a shield over the top half of them. Almost like an oversized 'eyelid'. Would that sufficiently reduce glare to a manageable level, while retaining brightness to see the road?
Or, what about HIDs in the fogs and just the fogs? The fogs are aimed lower, so would HID fogs give you good road illumination without blinding oncoming traffic?
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Alright, a few things:
1. Kind of. The issue with HIDs in stock housings is that stock housings are used to receiving a lot less light in general, so the light output is a different style, they focus less on the "cutoff," because the glare is not as prominent using halogen lighting, and also focus the light more in a "hot spot" in front of the car since they only have so much light to work with and they need to do something useful with it.
Now, when you put HID bulbs in halogen housings, you have basically a sphere as a light source (little gas capsule inside the HID bulb) instead of a line segment (filament in a halogen bulb). This means the light will be less focused and more scattered, since the housing was not engineered for the sphere source. Second, is that the sheer amount of light is amplified quite a bit. 9004 bulbs output about 700 lumens (45watt low beam) and 9007 bulbs are about 1000 lumens (55watt low beam). A 4300K bulb will output about 3400 lumens, and a 6000K bulb, which people tend to like more for reflector HID systems, puts out about 2200 lumens. Now, there is a certain amount of glare from factory halogen reflectors, but now not only are you making the light blue-ish (more prominent color for glare) but you're increasing the glare intensity 3-5 times. That makes for some uncomfortable glare.
2. There are HID bulbs built for reflector systems (D2R) that have a shield built-in, but an external shield would do better. People have done (there was someone who found the shields in Volvo HID reflectors) this and reported good results. Unfortunately you will still get the crappy beam pattern that the halogen reflectors give you, which focuses most of the light into hot spots directly in front of your car. Aftermarket housings i.e. aftermarket Cefiros and R34 housings will give you an even worse beam pattern, scattering the light into strange patterns and putting very little of it on the ground in useful places.
HID projectors (and to a lesser extent, reflectors) are engineered to put out a wide, even beam pattern with no hotspots. You have plenty of light to work with so there is no reason to focus it right on front of the car.
3. A lot of people actually aim fogs horribly so even with halogens they are still blinding. Fogs are not meant to provide illumination comparable to low beams. They're meant to light very close and wide, and in many cases are just for decoration (A32 fogs do squat). Using fogs as a main source of illumination is just a bad idea, you will not get much usable light out of them, especially if they're aimed correctly (down). I would not do it unless you just wanted to look cool.