Before the arguement flares up again, I'm going to copy and paste a post I have posted here before:
Confused said:Physically, you can just buy a set of HIDs, swap them into your standard headlights, and go on your merry way.
However, the way a HID bulb is designed, and the way a Halogen bulb is designed is COMPLETELY different, and the actual point-of-origin for the light is different.
When you have a set of headlights designed for Halogen bulbs, the focal point and beam pattern are designed to strict tolerances based on how a halogen bulb works.
When putting HID bulbs into a headlight designed for a halogen bulb, the output from the HID bulb is not focussed correctly, and the "downfalls" of the reflector headlight technology are exaggerated more.
Lots more details here
Here is a picture of the output from a standard Prelude headlight with a Halogen bulb:
.JPG)
And here is the output from a projector unit:
.JPG)
The standard headlight throws loads of light where it shouldn't go - upwards, this is due to the way the reflector is designed - there's nothing physical in place to direct/prevent light throw - it's the best they could do based on a standard halogen bulb! Adding HIDs to this will make this upwards throw of light even worse - yes it'll illuminate better in front of you compared to a standard halogen bulb - but at the cost of potentially dazzling oncoming drivers due to excessive light being thrown upwards - something the standard headlights are designed to, as much as possible, prevent.
With a projector unit, there is a physical barrier to make the light go where it's supposed to! This is why 99% of cars with HIDs from the factory have projector lights (exceptions that I know of are some Laguna's and some Mini's), as the HID bulbs ARE brighter - it's much much easier to direct the light properly with a projector than a reflector.
Yes - many people do just fit a set of HID bulbs to their cars and happily drive down the road, and go through MOT tests - however it's not recommended, and if they decide to clamp down on it properly, then it'll be a waste of your money.
The best way to improve your headlights is to follow this information, and add in additional relays to the headlight bulbs straight from the battery - cutting out the voltage drop through the standard wiring. This will GREATLY improve your headlights!! And all for the cost of a couple of relaysIf you then want to add some +50% or +80% bulbs, such as Osram Nightbreakers, then the difference will be even more staggering!!!
Garry
