Hey guys, antone know what the brightest H4 headlight bulb is? Also is H4 the same as 9003? I converted my Vespa to have a H4 but when I went to go buy a bulb (55/60w, preferably the "Blue") got real confusing. Any help?
Yes, 9003 is H4. If you're just looking for sheer brightness, you'll probably want to stay away from tinted lamps, even good ones like Silverstars, as they will reduce the total light output with their absorbing/reflecting tint. I'm thinking you should go for one of those "increased output" lamps like the Sylvania XtraVision or Philips HiVisibility.
Im running 80/100's in my Caprice SS now. But they are connected via a very heavy duty custom wire harness and emit the light through European spec t84 glass headlight capsules made by GM. Any higher than stock wattages and one risks burning up the headlight wire system and possibly an underhood fire. To avoid those hazards one needs to minimally upgrade the wires to handle the extra load..and also pay attention to the capsules to avoid melting or distorting the OEM plastic headlight capsules with the additional heat generated by higher wattage bulbs..
like hawkhkg11 said, if you want maximum brightness don't get a "blue" bulb which has a tinted capsule, it only blocks a portion of the light being emitted, the rest is reflected back within the lamp and the extra heat becuase of this is why they always burn out sooner then a regular bulb. If you go with a higher wattage bulb like 80 or 100W then the output is whiter then the regular 55w and you can get regular "non-blue" bulbs and still get a white output. upgrade you wiring though with new relays and at least 12ga wire.