I've seen all the pictures of the HIDs lit ON the car. Now what about some pictures of the HIDs lighting output on the road? Or how the cutoff looks like on natural road or freeway. Anyone have pictures of that? Very curious to see HID lighting output of different headlight housings. Especially since most are fluted. For some reason some fluted housings put out nice cutoff and output but some are just way off.

 

Recognize that all aftermarket adaptations of HID to light systems that were not designed for it are compromised. The main determinant of the beam pattern is the reflector. All of the aftermarket HID kits adapt a HID bulb to a base that will fit a non-HID type of reflector mount. The light source geometry isn't the same as the stock bulb, so the beam pattern isn't the same. Still some of them can work and provide good light without causing problems.

My feeling is that H5 (DOT USA) type reflectors provide a light pattern that is too diffuse to adapt to HID. You just end up blinding people.

I have H4s from a european 928 (you can buy the housings) with HID in them now. With regular H4 bulbs the beam pattern was very good with the H4 knife-edge cut-off at the top, making the lights were very easy to aim properly. I ran that for years with 80/100 (off-road) H4 bulbs and loved it. I decided to try HID. With the HID bulbs I got, the pattern had more scatter so the cut-off was not as exact and I ended up aiming them a bit lower to compensate for the scatter. The low beam pattern is still excellent. The ones I got have a shield that swings away when you switch to high-beam, and surprisingly, this works quite well. Switching to high beam lights up the universe for a long way down the road.

So, if you want better light, buy some H4 housings first. Run H4 halogens. The 80/100 off-road bulbs are an improvement over the 55/80 road bulbs, although they are technically illegal for street use. Then if you want something more try HIDs. But if you have H5 US lamps, do not install HIDs. I see so many people that put HIDs in H5 or other DOT type housings driving around blinding people.

I don't have pictures of the light pattern on the road at night and I think that would be hard to capture in any meaningful way anyway.

 

I agree with Bill's comments.

MTNKING, if you go to the rather ancient thread "H4 HID Conversion Kit Installed; Writeup Now Available" where I did a writeup on my HID installation, you can see the pattern of an H4/HID installation on some garage doors (see page 19 of the 20-page writeup).

I never did a "down-the-road" photo, but I could probably do that any time. The problem is, though, in the interpretation of such a photo. IMHO, it's meaningless without a good A/B comparison with halogens with no other variables, particularly with camera settings. What's needed, I believe, is two cars (or taking the time to swap out bulbs) and a camera in manual mode with the exact same shutter speed and aperture so that we don't just have auto camera settings screwing up the comparison.

If anyone in the Kansas City area with a 928 with halogen lights wants to provide their car with halogen lights and spend an hour or two setting up such a photo shoot, I'd be glad to give it a shot.

I can say that there's no question that the crisp cutoff you get with H4s (and the proper halogen bulbs) is gone when using retrofit HID bulbs. The notch is damn near unrecognizable and there's obviously way more scatter.

All that said, HID (again, IMHO) with H4 is great as long as you align the beam downward such that the increased scatter doesn't affect oncoming vehicles.




P.S. Bill, are you going to be at the DFW 928OCIC?

 

He has registered!

 

I'd just like to meet the persistent guy working through the nightmare "90 S4 Window Electrical Problem - UPDATE - More Help Needed" episode (and of course all the other stuff you've worked on and helped with, Bill).

(sorry for the OT)

 

Oh, yeah, I'll be there.