More ?? on 9007 vs 9004 bulbs rebuttal

[John Stanton]

Ok, more fuel for the fire.  I was kind of intrigued about getting better
head lights on my 95 90q and decided to do some independent research.  Here
is what I found.  Im confused now any truth to this?



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Re: 9007 headlight bulbs[200/1988] posted by Daniel Stern on
Sunday, 8 November 1998, at 6:55 p.m.

The 9004 and 9007 are not interchangeable for several reasons:

1) The filaments are in a different position, and oriented differently. The
9004 filaments are transverse to the bulb axis, and the 9007 filaments are
in line with the bulb axis. This is important because the reflector and lens
optics of a particular headlamp are based on specific filament position and
orientations. The US headlamp beam pattern is bad enough as it is--messing
with the filament orientation can only worsen it.

2) The pinout is different. The high feed, low feed and common (ground)
terminals are rearranged in the 9007 compared to the 9004.

3) The keying on the base is different, so a 9007 cannot be inserted into a
9004 headlamp or vice versa.

To answer your implied question, you don't have a wattage problem, you have
an objection to the US beam pattern, which doesn't generally do a very good
job of lighting up the foreground (road near the vehicle) and which tends to
produce a narrow, rather dim tunnel of light on the road with a "black hole"
directly in front of the car. European headlamp beams don't have this
deficiency at all, but US regulators at NHTSA like to pretend they know
better than the rest of the world, so we're stuck with this kind of junk
unless we're rich (to install the very expensive, but very good '86-'93 240
European lamp assemblies) or own a car with sealed beams that can easily and
economically be converted to European (H4 type) headlamps. "ten more watts"
would not help your headlamps a bit. 100/80w 9004s wouldn't either, for
electrical, mechanical and optical reasons which you can read all about at
http://lighting.mbz.org/faq in the "overwattage bulb" section.

If you're interested in more information about all of the different bulbs
used in headlamps and fog lamps, I've put up a comprehensive chart at
http://lighting.mbz.org/tech/info

--Daniel Stern
Stern Automotive Lighting Consultation
http://lighting.mbz.org/tech
Automotive Lighting Technical Info Centre