quick foglight question(S)

[CJFusco]

One of my foglights is brighter than the other. I'd like to get 2 new bulbs so that they can match.

What wattage should I buy? The foglights are H3s, right? Are all H3s the same?

[UconnTim97]

I replaced mine last year, I believe they were 55 or 60 watts.

[Panzer909]

You have two choices with H3 bulbs. They're sold at most auto part stores in either 55 or 100 watt versions. I just had a quick conversation with the local dealership parts manager who mentioned that the 100 watt ones are notorious for frying up early, and make the main headlights look weak.

I went for the 55 watt ones with no problems.

[nize]

the 100 watt ones do burn out faster, and do make the headlights look weak, but you can't beat the extra light when the road is dark.

i usually buy two at a time so i have an extra in case one burns out early.

[IceShark]

If you have the OEM fogs on that early 944 they should be H3 bulbs. 55 watt is stock. Some people run 100 watt but there can be wiring and heat issues, and on an '83 you may melt the insulation off your stock wires @ 100 watts. They also don't work as fogs very well with 100 watt as the light backscatter off water droplets hurts your vision.

As to why one light is dimmer than the other, there could be four probable reasons. Road rash/sand blasting of the lens. This will diffuse the light and degrade the beam pattern. Not much you can do other than replace the lenses. Some have had luck with polishing up with compounds used in making telescope mirrors but that is a lot of work for not much cost savings.

The reflective coating on the reflector could be corroded. Replacement time as there is no cost effective way of fixing that.

Bad wiring to the dimmer bulb. Light output from a halogen varies at the 3.4th POWER to voltage changes. Lose just 15% of your voltage and you lost 50% of light output.

The final is just an aging or poor quality bulb. What happens is tungsten from the filament gets deposited on the glass envelope. It acts as a filter and cuts light output. In real bad cases you can see it as a gray/black film on the glass. In not so extreme cases you can't really see it with the naked eye, but it is there and that is a reason to never compare old and new bulbs for manufacturing quality. An old bulb that has burned for XXX hours is going to be at a disadvantage in light output.

I could sell you some quality German manufactured Philips/Narva 55 watt H3s for $5 each but the shipping would probably be 4 bucks for just a pair. See what your local auto store wants for a pair of the same or Osram/Sylvanias. Stay away from junk bulbs.

[IceShark]

Oh, and there is no mystery that 100 watt H3s burn out faster. For example, Philips characteristic T life (when 63.2% of the bulbs have failed) for a 100 watt H3 is 100 hours. 55 watt is 450 hours.

130 watt is 40 hours. You pay a price for more light.

[CJFusco]

thanks for all the help.