REPOSTED FROM CLUBPROTEGE. ORIGINALLY POSTED ON 10/05/2003.
All rebutals regarding HID retrofits WILL NOT be tollerated as it's been clearly explained that they don't work as intended and testimonies stating "they work fine" are without any scientific basis which means they're WRONG.
NHTSA didn't "discover" HID "retrofitting" was bad after they were in the market, they knew about it years ago. NHTSA just chose not to be proactive about the issue until there were numerous complaints about excessive glare.
Based on CURRENT technology, HID retrofitting is ILLEGAL *anywhere* in the world and will be as long as humans roam the earth. Keyword "CURRENT". This does not necessarily mean there won't be a legal one that meets photometric standards of either UNECE r98 or FMVSS/CMVSS108.
To everyone going ape**** as to why NHTSA is being such an ass about it, you are ignorant. Wait, don't be pissed. You NEED to learn WHY they are illegal first and understand scientific facts before you have the right to comment. In most cases, people who went from "ignorant" to "informed" have no comment.
So now, the basics.
There are several issues as to why HID (or gas-discharge) lighting must be heavily controlled. One of them is the high light flux from the xenon balasts. They are not "brighter", they are simply more efficient at outputing light that meets the 150000 candela limit requirements. Because it is so effective at this, HID headlights' beam pattern MUST have a cutoff. MOST halogen headlights still on the road today do not have a beam pattern cut off due to the inherent characteristics of the SAE/DOT beam pattern design (lots of "scattered" light). Most of the people performing these HID "retrofits" are doing it to older vehicles that have such headlights. So that's one issue.
What's the other one? Fitment of the capsule itself. D2R capsules are NOT designed to be crammed into a HB2,9004,9006,9007,H1,H7 or ANY halogen housing. When you do this, the bulb either doesn't stay in place very well (as demonstrated by many board members here) or is geometrically offset even when it is "well secured". Ok, to understand this fact better, think of your typical maglite where you have the "zooming" feature. When you have the bulb too far out or in, it changes the beam pattern of the light dramatically.
So, here's an example of the BAD results when you just cram bulbs into the wrong housing
there's no need to comment on how fubar it is
this is coming from a P5 with Audi A8 capsules, but the owner chose to use just the xenon capsules and *not* the projector housing... this makes it not "A8 lights" anymore
Ok, now that we understand the number 2 important fact of "why", let's go to the other one. How does the light appear IN the bulb housing itself? We know halogen bulbs uses a filament. We also know xenon bulbs have no filaments are filled with as the name implies, xenon and other trace gases. Ok, so when a xenon bulb is turned "on", the gas gets electrically charged, but based on phsyics (which I basically know nothing about), the electrically excited xenon gases want to move away. This is stopped by the glass capsule. So the effect that we get is an arc that starts from one end of the capsule, curves upward, then back down at the other end. How does this differ from a halogen bulb? A halogen bulb just glows in a cylindrical shape due to the filament and depending on how the filament is placed in the balast determines the geometric position/"center" of the light. So how does this affect the beam pattern when you put in a "misaligned" bulb? Simply put, you get an unpredictable beam pattern that can range from spotty lighting, or just a high beam-like beam pattern. So what about those "dual beam" HIDs? They do nothing but rob you of funds, that's what. How it works is an electromagnet is energized located next to the xenon balast and when that happens, it moves the arc to a different location. Because of the unpredictability in controlling the geometric position of the arc properly, it has NOT been used in ANY OEM application.
So now, the last thing. Most of you will now go "but my beam pattern is fine!" That's good for you. One thing that you can't see is the light distribution in various areas of the beam pattern's light field. For one thing, because of the increased light flux of the HID light, the hotspot intensity has been exponentially increased and therefore the halogen's light housing does not have the ability to control that (redirect) light to safe levels. Other typical places where excessive or insufficient light has appeared is usually at the far left of the light (in the negative quadrant) and at an area at the lower part of the positive quadrant. So wtf does that have to do with pissing people off? Increasing the hotspot also means increasing the glare because the hotspot is where most of the "stray light" comes from. So why is there a hotspot anyway and why didn't they take that **** out to begin with? Simply not possible because the hotspot is also where the most light is (the light bulb), and also because of the fact that without it, you cannot light up overhead roadsigns effectively. Now as for the light in other areas of the beam pattern, you will either not see as effectively in those areas, or you will have lighting way over the legal limit (limits which were put in place to prevent glare "coming from the corner" and going to someone's mirror).
This is recent, done on a 02 protege ES with HB2 housings: http://www.msprotege.com/forum/attac...achmentid=6282
notice that the beam pattern has changed and you can tell already that the increased light flux at the hot spot is causing excessive glare just from the light above the cutoff alone. Notice the major reduction in light at the far edges of the beam pattern. Also notice the reduced amount of light at the very bottom of the wall (if this was shining on the road, it would be reduced light CLOSE to the car). That's it for basic analysis.
So, based on these BASIC scientific facts, there is NO way anyone can argue with NHTSA or UNECE about their decision to making HID retrofitting illegal. In otherwords, you can't convince them to making them legal to use.
Don't give your hopes up. The experts KNOW that HID can be beneficial. So, they are actually working on a SAFE and legal retrofitting method for existing/older vehicles (this is still years away though).
And for you people confused about HID being "illegal", it is not. RETROFITTING is. Any car that has HID installed as original equipment is expected (in America, in the case of Europe and anywhere else in the world, absolutely yes) to be legal and meets all specifications outlined in FMVSS108. But what about safe and proper HID light housings? Does that mean you can put those on a car? It'll be VERY safe yes. But according to NHTSA's weird interpetation of the law, if it's not original replacement equipment, it is illegal. This means whatever comes out of the vehicle must be replaced with the same type. In the case of MANY vehicles with specially designed light housings from the factory, if you break it, you have to replace it with the same kind.
And a little bonus for you all who have attentively suffered through this long post... this is what a PROPER H4 halogen beam pattern based on the UNECE r20 specification should be like (this is from my car and is equiped with Osram Silverstars):
and you think I didn't suffer? I spent an hour writing this!
here's a pic of what a real HID beam pattern should look like... from a European spec 2000 Audi S4 housing (UNECE r98 right hand traffic compliant) using D2S capsules:
very even light distribution, not big blobs of light
and the US-spec DOT VOL HID beam pattern of a 2000 Audi S4:
much more weaker lighting