headlight relay install

[RoninLB]

I just did a copy & paste from the site...............
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? ...............party hearty.............Ron

[Decolliber]

Nostatic suggests that the relay is a good idea even if you do not plan to use higher wattage bulbs, because the head light switch can wear out from having the current pass through it. Is this also true of Carreras? I ask because most of the participants in this thread have SC or earlier cars. Do they all use the same (vulnerable) headlight switch?

[steve911]

John C -

YES -
check out this thread and then follow the other links in my post (steve911) there on whether or not relays are needed for all 911s (they are).

[RoninLB]

Dec.....Allan Caldwell/PCA tech. advisor/'78-'89 911 suggests a dual relay upgrade on a stock headlight system..a 4 relay system may be safer..he suggests a 40amp relay on a dual relay system and a 25 amp fuse on each of the 4 hot wires between relays and headlights..I use a dual Bosch 75 amp relays and circuit breakers before relay battery power.........Ron

[Jdub]

My weekend was spent putting in this kit. You can view at Turn sig. low/high beam switch

I cut the "block" ends that Porsche used as fingers into the fuse ends and soldered the white/yellow to black/black. This is a permanent fix and so no need to back out. I was able to put the relays and all wiring under the fuse metal tray and use a spare fuse block to put in a 25amp blue as the flying fuse from the + side of the battery (the yellow wire to the relay).

Great kit. Everyone running H4s or non-stock needs to put this in the car.

John

[john70t]

I just put in an H4 relay kit into the t, will post pics.

Checking connections are tight, shrink tubing, plastic wire protective tubing, and using electrical tape on the clean, de-greased grounds worked o.k. (though too late to save a fried wire ).