Anyone hear why Chevrolet went to a halogen high beam on the C6? Why didn't they use BMW's and Porsche's technique of using a shutter system so the same HID bulb could be used for both high and low beams?

With the low beam left on with the high beam, you are going to get way too much foreground light at higher driving speeds, especially with a low beam using an HID bulb with three times the light of a halogen.

Michael

 

I don't think it will be halogen because I don't think a halogen will work with that type of lens. Will it?

 

We have two vehicles with HID low beams and "old school" high beams. Not problem with lighting at night. You can tell where the low beams drop off in the distance, though, as the color change from white to the yellowish of halogen light is evident.

I thought GM would go HID for low and high beams. Is this not the case? If not, GM is a little behind on a brand new design.......

Todd


[Modified by WhiteDiamond, 11:18 AM 6/27/2004]

 

 

They've been using halogen bulbs in projector lenses for years. Perhaps GM did not want to raise the cost or add more complexity to the headlamp assemblies than was necessary. Honestly, with the increased light output of the low beams, how often are you going to need the high beams except in flash-to-pass scenarios? I rarely use the high beams at all in my M3.

 

In a four-bulb system, Halogen is the only choice for the high beams because otherwise you lose the ability to flash.

If GM went to a two-bulb system, it would add weight and complexity because of the added moving parts which would be used to move the headlamp assembly and/or shutters to flash your highs. The whole point in going with this setup is to avoid weight and complexity. The direction GM chose is the absolute best for a performance vehicle.

 

The following auto manufacturers have bi-xenon lamps on their high-end models:

Acura
Audi
BMW
Cadillac
Ferrari
Infiniti
Jaguar
Mercedes
Nissan
Lamborghini
Maserati
Porsche
Saab
VW

I guess it depends on where one lives, if this is important or not. Where I live, the C6 system is highly compromised. I'm concerned about distance vision on unlit roads, and this is not the "absolute best for a performance vehicle". The absolute best is a system which turns off the low beams, when the high beams are on, just as the fog lamps are turned off (even on two lamp systems). I'll take the extra pound or two, and the complexity, so I can see. Besides who cares about complexity, on a car with electric everything, including the door latches?

If anyone would like to try this out, here is a good test. Go out to a desert road, preferably one with lots of turns at the end of long straights (very little contrast), and drive it at a decent speed. Drive for a while with your C5 flash to pass on (it leaves the low beams on). Then drive for a while with just your high beams on. You'll see that the foreground light kills your long distance night vision. It's only going to be worse with the C6 HID low beams.

I think there is a different answer to this, perhaps cost. Maybe they are planning ahead for LED headlamps. I would appreciate hearing GM’s answer to this. Maybe someone can ask Dave Hill next time they see him.

Michael

 

Driving around on unlit, curvy back roads at night like I do, I've seen what it's like to have high and low beams on at the same time. It's superior.

My distance vision isn't compromised at all, and the low-beams provide the necessary spread to avoid close-in hazards such as road gators, bags, potholes, and animals that the high beams are too narrow to illuminate. Perhaps there are some people who are overly sensitive to the low-beam light, but I'm not one of them. Nor is the wife, and she gets migraines (naturally, not from the headlights.)

Those who have driven the C6 even commented on how great the lighting was in both low- and high-beam modes.

 

I can see this if you are driving pure tight curves. Sometimes I will switch to low beams if it is tight. What car do you have that keeps the low beams on with the high beams? I've not seen any Corvettes do that.

Where this breaks down (driving with low beams and high beams together) is driving high speeds on straight aways. Anything that is within the low beam is already too close to react to. In fact, out in the desert, the weak US high beams are already extremely marginal, even with the low beams turned off. To my knowledge, no auto manufacturer prior to HID left the low beam on with the high beam. You'll recall that the outboard lamps on the old 4 lamp systems had dual filaments.

Another thing that I think is going to be annoying is the color shift going from high to low to high beams (yellow with blue foreground to blue to yellow with blue foreground).

Michael

 

I installed a relay to turn on the high beams with the low beams on a HID kit I installed on another car.

Those back roads I drive on include straightaways. I still see fine with low and high beams on.

More like white to yellow and vice versa. Sunlight is the same color temperature as the C6's low beams. It's a pure white. It only seems blue at first because we're used to seeing yellow lights so often at night.

 

I was amazed at how well the lights work. You can see much further without the need for high beams. The light pattern is unbelievably flat, like a straight line perfectly parallel to the ground.

I personaly like the additional foreground light of having both high and low beams on at the same time. In Michigan, as well as many other states, Deer are a major problem and the additional foreground lighting provides greatly needed lighting. Like Scissors, I added a relay to my Yukon to make all haeadlights function when high beams are on.

If you are truly concerned about the need for a HID high beam, I wouldn't doubt that an aftermarket company will offer just what you are looking for very soon. Be prepared for a pricey kit if they make it.

 

 

Sorry Scissors, I edited my post.

 

That all depends on what time of day you are talking about.

Here's some interesting data from the Kodak website:

Sunlight: Sunrise or Sunset 2000
Sunlight: One Hour After Sunrise 3500
Sunlight: Early Morning 4300
Sunlight: Late Afternoon 4300
Average Summer Sunlight at Noon (Washington, D.C.) 5400
Direct Mid-Summer Sunlight 5800
Overcast Sky 6000
Average Summer Sunlight (plus blue skylight) 6500
Light Summer Shade 7100
Average Summer Shade 8000
Summer Skylight Will Vary from 9500 to 30000

For comparison, the Osram website their HID bulbs are 4100K, except for their aftermarket low beam auxiliary lamp, in which case it is 5400K. From the chart, it looks like HID headlamps mimic early morning/late afternoon sunlight. You'll notice that if you factor in a blue sky, the ambient color temperature is even higher. For instance summer shade is 8000, while Mid-Summer Sunlight is only 5800.

Arc lamps have emission bands, so technically they can't generate pure white light like a black body radiator can. That's why you see a color rendition index (CRI) on arc lamp specifications. I have never seen one for HID headlamps, but my guess it isn't very high since color rendition is not the main priority.

Michael

 

Mr. Scissors, you're leaving yourself wide open on this one!

I'm going to be a gentleman, walk away, and pretend I didn't see it.

Michael

 

That would be the one which the C6 is set to.

HIDs are a lot more pure than halogens, considering that they broadcast much more of their radiation in the visible spectrum. Halogens, on the other hand, waste a lot of energy in the IR spectrum, keeping the average color low and giving an orangish/yellowish tint.

 

I guess I understand your term "pure" now, a cross-correlated description of lamp efficiency and color temperature.

Michael

 

"Bi-Xenon" is a clever marketing name and is actually a misnomer. My BMW330i's "Bi-Xenon" headlamps consist of a HID low beam with a servo-actuated reflector, and separate, hi-beam only lamps which are Halogen. The purpose of the lo beam servo is to move the cutoff ring out of the way on the lo projector so the full reflector is used. (The "razor sharp cutoff" claimed by projector manufacturers is nothing more than a blocking strip which eliminates the bottom half of the reflector light).

As was mentioned, you lose flash when you eliminate the halogen altogether, because the HID lamps cannot instantly generate full power output. I suspect that problem will go away in successive generations, as they improve the ballasts, enabling the plasma arc to stabilize quicker. It will then be a HID only show.

Bosch Litronic (Porsche) also uses servo reflectors on the HID lo, and augments them with a halogen on hi. It looks like HID only because it is all integrated into one housing, but the halogen highs are in there.

I have no idea what the C6 uses, but I suspect it will also have the servo-actuated lows since it too is a projector design. Not sure why it employs a projector high, but that's another story.

 

What year BMW do you have? The new BMWs don't turn on the halogen except for "flash to pass".

Michael

 

That is incorrect. The halogens are in use whenever the high beams are on. Mine is a 2003 with the bi-Xenon (see my signature). Prior years had only "regular" xenon in which the low-beam reflector has no servo actuation.