Brad,
I will not dispute that there's always a remote possibility of an HID PnP kit work decently in a halogen housing. NBS Depo halogen projector housings are famous for providing a decent cutoff and beam pattern. BUT, when this happens it is incredibly rare and a result of coincidence rather than planning by the housing manufacturer. We know this cause none of the other Depo housings are so lucky.
Why?
Well, it'd take a stupidly long post on my part to outline it all, but here are a few reasons.
1. Halogen housing designs are incredibly varied and although it may not seem so, are complex pieces of engineering designed and optimized specifically to work with its corresponding type of halogen bulb (H1/H11/H13/etc).
2. The number designation of a halogen bulb is not limited to its base connector, otherwise they'd be a universal base connector. The number also designates the way the bulb illuminates, location of hotspot, depth in the reflector, whether it sits before a cap, whether it's in a fresnel housing lens, and many other variables.
3. Keeping No. 2 in mind, there is no such thing as a HID oem bulb. Philips, Osram/Sylvania, Hella, etc, have never, nor will they ever manufacture an H (halogen) designated HID bulb. When someone buys a say H11 HID bulb, it's a generic hid bulb connected to a halogen base ... this process is called rebasing and at a large scale it is very imprecise, and very rarely if ever are quality oem HID capsules used.
4. Keeping Nos. 2/3 in mind, cheap HID rebased bulbs, due to their low quality, rarely maintain a consistent hotspot, and given their own inconsistency and the different housings they'd reside in, matching the two into a proper beam is all but impossible.
5. Especially because HID bulbs illuminate in a completely different way that is by definition scientifically incompatible with halogen reflector housings. If one tries to put a H1 halogen bulb in a Mini H1 HID projector, the result is equally poor, that is simply because the incompatibility is applicable both ways.
There's a lot more but you get the drift, too many moving variables and incompatible optics/designs ... not impossible for them to properly coexist, but statistically highly improbable.
A couple of last points if I may bore you more ...
Quality of the HID PnP kit has very little to do with the resulting illumination, unless the aftermarket bulb is so poor that it doesn't work. Quality matters in the sense that if the kit is poor, it will not work, will use ballasts with the wrong current (AC instead of DC), will use cheap harnesses with inferior cable, all of which can result anywhere from headlight failure, to stuff melting inside the housings or the engine bay, or in rare occasions set the front end on fire. It happens.
But even if one were to use oem ballasts like Denso/Hella/Matsushita, high quality harnesses, and even pay an expert to rebase the highest quality oem bulbs in an H connector, all the elements I outlined above would not change and neither would the resulting output. One would simply have a high quality PNP kit with less chance of failing and/or inflicting damage.
Last ...
There is a massive misunderstanding and lack of knowledge as to what 'DOT approved' means. The DOT never approves or certifies anything related to headlights. The manufacturers are the ones responsible for ensuring that their lights meet NHTSA and DOT guidelines and express this by indicating DOT approved on their components. The DOT does do random testing to make sure that this is the case. But the idea that anything that says 'DOT approved', simply because it says so, can be used interchangeably is erroneous.
The process is simple, different manufacturers of lighting components self certify as DOT approved, be they Halogen/LED/HID/filament. Car manufacturers combine them for their vehicles, and once they are installed in the factory it is illegal to modify any element of them other than replacing a bulb like for like. This is specifically to prevent people from mixing and matching lighting components at will for the reasons I outlined above.
So even retrofits like mine where every component may have DOT approved stamped on it, are illegal. The only difference is that retrofits if executed properly, mimic oem setups whereas PnP kits don't. Still illegal, but less egregious to others and less likely to raise a leo eyebrow.
Yikes ... tired now.
More info in sig linkies.
I will not dispute that there's always a remote possibility of an HID PnP kit work decently in a halogen housing. NBS Depo halogen projector housings are famous for providing a decent cutoff and beam pattern. BUT, when this happens it is incredibly rare and a result of coincidence rather than planning by the housing manufacturer. We know this cause none of the other Depo housings are so lucky.
Why?
Well, it'd take a stupidly long post on my part to outline it all, but here are a few reasons.
1. Halogen housing designs are incredibly varied and although it may not seem so, are complex pieces of engineering designed and optimized specifically to work with its corresponding type of halogen bulb (H1/H11/H13/etc).
2. The number designation of a halogen bulb is not limited to its base connector, otherwise they'd be a universal base connector. The number also designates the way the bulb illuminates, location of hotspot, depth in the reflector, whether it sits before a cap, whether it's in a fresnel housing lens, and many other variables.
3. Keeping No. 2 in mind, there is no such thing as a HID oem bulb. Philips, Osram/Sylvania, Hella, etc, have never, nor will they ever manufacture an H (halogen) designated HID bulb. When someone buys a say H11 HID bulb, it's a generic hid bulb connected to a halogen base ... this process is called rebasing and at a large scale it is very imprecise, and very rarely if ever are quality oem HID capsules used.
4. Keeping Nos. 2/3 in mind, cheap HID rebased bulbs, due to their low quality, rarely maintain a consistent hotspot, and given their own inconsistency and the different housings they'd reside in, matching the two into a proper beam is all but impossible.
5. Especially because HID bulbs illuminate in a completely different way that is by definition scientifically incompatible with halogen reflector housings. If one tries to put a H1 halogen bulb in a Mini H1 HID projector, the result is equally poor, that is simply because the incompatibility is applicable both ways.
There's a lot more but you get the drift, too many moving variables and incompatible optics/designs ... not impossible for them to properly coexist, but statistically highly improbable.
A couple of last points if I may bore you more ...
Quality of the HID PnP kit has very little to do with the resulting illumination, unless the aftermarket bulb is so poor that it doesn't work. Quality matters in the sense that if the kit is poor, it will not work, will use ballasts with the wrong current (AC instead of DC), will use cheap harnesses with inferior cable, all of which can result anywhere from headlight failure, to stuff melting inside the housings or the engine bay, or in rare occasions set the front end on fire. It happens.
But even if one were to use oem ballasts like Denso/Hella/Matsushita, high quality harnesses, and even pay an expert to rebase the highest quality oem bulbs in an H connector, all the elements I outlined above would not change and neither would the resulting output. One would simply have a high quality PNP kit with less chance of failing and/or inflicting damage.
Last ...
There is a massive misunderstanding and lack of knowledge as to what 'DOT approved' means. The DOT never approves or certifies anything related to headlights. The manufacturers are the ones responsible for ensuring that their lights meet NHTSA and DOT guidelines and express this by indicating DOT approved on their components. The DOT does do random testing to make sure that this is the case. But the idea that anything that says 'DOT approved', simply because it says so, can be used interchangeably is erroneous.
The process is simple, different manufacturers of lighting components self certify as DOT approved, be they Halogen/LED/HID/filament. Car manufacturers combine them for their vehicles, and once they are installed in the factory it is illegal to modify any element of them other than replacing a bulb like for like. This is specifically to prevent people from mixing and matching lighting components at will for the reasons I outlined above.
So even retrofits like mine where every component may have DOT approved stamped on it, are illegal. The only difference is that retrofits if executed properly, mimic oem setups whereas PnP kits don't. Still illegal, but less egregious to others and less likely to raise a leo eyebrow.
Yikes ... tired now.
More info in sig linkies.
