Main Beam HID's

[Jakg]

ignoring the usual powerwash / self-levelling arguments, what else do I need to know if I want to fit an HID kit to my main beam? Will it pass an MOT?

It would be a reflector so would need an H9R bulb

Already fitted them to the dipped beam.

[HellDiver]

They're pants, having to wait a few seconds for them to fire, then brighten up isn't necessarily a good thing for beams. Fitting 100W bulbs is probably easier and safer.

[rottie102]

Jakg said:

ignoring the usual powerwash / self-levelling arguments.
Already fitted them to the dipped beam.

I'm sure you're pretty proud of yourself, idiot.

[Jakg]

rottie102 said:

Jakg said:

ignoring the usual powerwash / self-levelling arguments.
Already fitted them to the dipped beam.

I'm sure you're pretty proud of yourself, idiot.

...wut?

My lights are aligned perfectly well thanks, and I have a set of reflectors in the post.

I don't see powerwash as necessary (although i will admit legally it is) and self levelling only seems valuable if you carry lots of weight - if I do I will manually adjust it anyway.

[volvoforlife]

Why is powerwash so essential? Theres plenty of headlights on cars with no washer at all?

[kambites]

volvoforlife said:

Why is powerwash so essential? Theres plenty of headlights on cars with no washer at all?

I don't claim to fully understand, but I think it's something to do with the way that the light scatters when there is dirt on the lens. HIDs tend to cause a lot of glare when they get dirty.

[snoopstah]

volvoforlife said:

Why is powerwash so essential? Theres plenty of headlights on cars with no washer at all?

HID bulbs put out more light than normal halogen bulbs (normal bulb around 1200 lumens, normal HID around 2800 lumens). Therefore if there's dirt on the lens, the dazzle will be brighter.

(We'll ignore the fact that a gentle spray of water onto the light is realistically going to have at best a minimal cleaning effect, and will temporarily make things worse).

HIDs retro-fitted in reflector-type headlights are pretty awful, the headlights are designed around the bulb's output being in a very specific location, and the HID bulbs are unable to generate the light from that location (regardless of what the Chinese eBay sellers claim), so the light is mis-focused and hence reduces the light on the road where you need it, and increases the scattered light, dazzling people. They're also very easy to spot as being fitted aftermarket so you're asking to be pulled.

HIDs retro-fitted in projector-type headlights generally work better, as they are less dependant on exactly where the light is emitted from the bulb. Also, as the light beam cutoff is controlled outside of the projector unit itself, you don't generally have the dazzle factor.

[Pigeon]

snoopstah said:

Also, as the light beam cutoff is controlled outside of the projector unit itself, you don't generally have the dazzle factor.

Why do people keep saying this? With both reflector and projector optics you're sufficiently far off the axis of the oncoming car's dipped beam that the sharpness of the cutoff is irrelevant. Dazzle comes from the light scattered from dirt and imperfections on the outside lens. It is worse for projector optics because the beam is more concentrated so the spot of scattered light is more intense. With reflectors the patch is broader and therefore dimmer and less dazzling.

The biggest problem with dazzle in any case comes from dicks with badly misaligned lights, irrespective of what type of optics they have or what bulb technology they use.