PIAA "Superwhite" bulbs produce exactly the same amount of light as any
other bulb in a given bulb format (9004, 9005, 9006, H4, etc.),
plus-or-minus 15 percent (which is the US FMVSS 108 Part 564 tolerance for
variations in luminous intensity from headlamp bulbs).
The "55W = 85W" type claims are a sham. Here's how these kinds of pretend
wattage numbers are cooked-up: The filaments in PIAA "Superwhite" bulbs are
wound on a larger mandrel than regular filaments, so there are fewer
filament coils, of a larger diameter. When these bulbs' luminous intensity
is measured using the appropriate device (called an integrating sphere),
they come up within the FMVSS 108 Part 564 tolerance range for whatever bulb
type is being tested--no more. (If they didn't, they would not be permitted
to be marked DOT, and they are, so they do.)
When a bulb with such a modified filament stack is placed in a headlamp, the
different dimensions of the filament alter the beam pattern. In most
US-specification headlamps, what this does is reduce the size of the central
"hot spot" of the beam and put more light in it, while taking away light
above, below, to the left and to the right of the hot spot. Then the PIAA
marketeer comes up with his light meter, sticks it in the hot spot of the
beam, and says "Nifty! The hot spot is almost as bright as it would be with
an 85W bulb!" and rushes off to order-up a new batch of boxes festooned with
"55W = 85W" banners. Then Mr. Consumer comes along, plunks-down some $70
(!!) for a pair of these bulbs, puts them in, and though his headlamps look
"whiter", he has just screwed himself. How?
Well, the reason why many people find many US-specification headlamps in
need of upgrading is because many US-spec headlamps have insufficient
foreground light, which creates a "black hole" on the road in front of the
car. There's often insufficient lateral light (left and right) to see
critters or people before they run into the road. The "hot spot" creates a
narrow tunnel of light that disappears "out there somewhere". By making the
hot spot smaller, this narrow tunnel of light gets smaller. By taking away
(already scarce) light from the foreground and sides, the situation is made
worse.
Kenichi
94' Sentra E
Ga16de
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