The glass capsule in all hid bulbs more or less have equal size, regardless of manufacturer, rebaser or whether its a OE based (p32-d), rebased or custom base. The length of the glass capsule is around 52mm long and requires a hole in reflector of minimum 15mm and a radius of 13mm where return wire is. This means that kits that are ment to fit all headlamps using a specific halogen type bulb, isn't true in real life. In many cases, they will require more space, in one way or another. Making this space is usually possible, but it might introduce other challenges, such as increased glare, reduced reflector area, or irreversable retrofit.
If you can see the filament in the halogen bulb in your current housing while standing in front of your car, you have to use a shield around the HID bulb. Some HID kits supply a shield. If not, you can also make this shield yourself, but it will take time and you will probably need tools and materials. The reason for needing this shield is that HID bulb gives out around 2-3 times the light compared to a 55W halogen. And that is too bright to look at without sunglasses. All free form headlights (glass is not textured) will need a shield. Reflector based headlights with textured glass have a built in dampening in the glass and you might get away without a shield. Projector type headlamps already have built in shields, so there is no worries there.
Picture below: possible glare reducer by high temp painting bulb
The 2 types of glare shields:
Shields can be made at home as well, just use either a turkey baster or a touch up paint can as donors. Tuch up paint can is the best choice because the end of the cylinder is closed. The turkey baster is open in both ends, unless you are able to still get the long "spout" into your headlight, which depends on the available depth. Picture below shows how the turkey baster version should look like this after cutting and high temp painting.
The flat black high temp paint on the shield will absorb almost all light shining on it
and convert it to heat. If heat is a concern for you, use flat gray high temp
paint. It will not be as hot, and still give enough light absorbtion and deflection for most
applications.
Note that in some cases, glare levels are not possible
to bring down to acceptable levels, no matter how good shields you build.
Another dead end you can face is that you need to cover up so much of the
bulb that the actual gain of using HID is only minor.
Yes and no. First of all we have to separate between useful
and useless light. HID bulbs sends out orange/yellow colors downwards,
and that is unwanted light. Light that doesnt go downwards towards
the road are definatly useless. There is no point in lighting up trees and walls,
blinding other traffic and pedestrians. Adding shield will make your beam
look much whiter across the beam. A metal shield directly on the glass will reflect alot of heat back to the
bulb, increase bulb temperature and lower bulb life. Choose around
9mm distance from glass. This will also leave
enough space for the high voltage return wire. According to manufacturers
specs, distance return wire to foreign elements has to be min. 5mm Expect a bulb temperature of 350-700 degrees Celsius, so stick to metal.
Read the Tools and materials section
throughly before adding foreign items inside headlight. It is crucial that
all items can withstand alot of heat.
These pics is taken from the rear of Mercedes reflector headlamp. It is
designed to use a D2R bulb. It shows that the lower 180 degrees of reflector is
not in use. This is not uncommon among cars with OEM HID reflector based
headlamps. It is the pinstriping on the D2R bulb that will determine
alot of cutoff line, not the underbelly shield. A similar shield approach can be
taken when converting a single filament halogen based reflector headlamp
to HID. Various Halogen bulbs and HID:
Will output be lost by adding shield?
How close can shield be from bulb glass?
What materials and adehiesives can be used to fabricate shield?
How does shield look like from OEM?
This section will describe the common factors that are found in headlight
types that uses various halogen bulbs. This is in many cases too generic
and must be read together with the HID
upgrade routes.
H1 HID:
Depth: H1 capsule is 19mm (44-25) from base of filament
to the tip. The same distance on an HID capsule is 23.3 mm (52.5-27.1-2.1).
You should leave 5mm distance for the HID bulb return wire. So the required
depth is now 28mm (23.3+5). This means that you need 9mm (28-19)
extra depth. In a reflector housing it can hit the glare box, if it exist.
In a projector housing, it will typically hit the cutoff shield.
(Pics are not in the same scale)
2) Diameter: The hole diameter in the reflector is almost equal (1mm difference). However, the hole has to be made bigger so that the return wire gets its 5mm distance to metal. The return wire is 8.7mm away from the center. Add 5mm and you need 14mm of cutout from the center. Even if you have plastic reflectors this has to be taken into consideration. The reflective material is a chrome substance, and is indeed an electrical conductor.
Many kits out there makes you give up high beam. Some people claim that HID will give you the extra light, so high beam becomes unneccsary. This is not true. There are high/low kits you can use - see "aftermarked Bi-Xenon kits" on this page.
Physical measurements:
base to start of filament: 28.5mm
glass diameter: 17mm
base to tip of glass: 59mm
H9 is originally a 65W desgined for high beams. Lumes difference up to a 35W HID bulb is the lowest among all halogen bulbs, so this will normally make a good retro. H9 have a 27mm distance from reference plane to bottom of filament.
9007 HID:
In 99% of all housings that utilises
9007, you
will never be able to get OEM quality ligthing with an HID upgrade kit.
Theoretically H4 has a better success rate than 9007. At least H4 is designed
to use top part of reflector only, which helps when you want to decrease
light above cutoff. High and low beam are selected by using 2 different
filaments above each other. Low beam filament sits above high beam filament.
9007 based reflectors utilises most of the reflector area in both modes.
This means that a shield is needed to block bottom part of reflector to
hinder yellow light to reach the road. So far so good. But what about the
increase light above the bright oval? That will be totally overfilled with
glare. Also, filament length is 5mm. The HID filament is 4.2mm. That will
make an HID upgraded 9007 have a smaller, distorted and partially intense
pattern with possible blacked out center. Outside that you will notice
the increased glare.
Conclusion: If you are able to
(do or pay for) a custom job by using stock housings, it will take so many
hours to end up with an half decent job that you would be better off taking
a part time job and buy OEM HID houses, if they are available. They are
available for 98+ Ford F150 and Expedition (directly off of Sylvanias site).
Even if you retrofit projectors from a well functioning setup (see OEM
HID overview page), into your headlights or create your own bracket, it
would still be worth it, qualitywise. Also see the discussion regarding
loss of high beam in the H4 section.
Remaining Halogen Bulb Specifications:
