Are 9004 and 9007 lights interchangeable?

georryan · Post by **georryan** » Sun Sep 14, 2003 6:15 am

I'm looking to buy some brighter lights. Currently I have 9004's in my headlights, but if the picture I've looked at is right, the 9007's look like they are the same but just have a closer brightness between their low and high beams. Is that true, or am I way off? Is it bad to put 9007's into our headlights?

vrg3 · Post by **vrg3** » Sun Sep 14, 2003 4:31 pm

The connectors for the two bulbs are almost the same physically, but that's about where the similarities end.

You're right that 9004s generally have 45-watt low beam filaments while 9007s have 55-watt filaments. But in addition, both 9004 filaments are transverse while 9007 filaments are axial. Axial is generally better because it allows more of the light to be usefully aimed, but you really need the entire optical system to work together. So if you put a 9007 bulb in a 9004 headlamp you'll have a light source with the wrong shape and in the wrong position for the reflector and fluted lens. That means a bad beam pattern.

The connectors aren't exactly the same, I don't think... There are some grooves that are in different places, and the pins mean different things.

You could in theory cut the new grooves and switch the wires around, but I really think you should stick with the right bulbs. Brightness is not as important a property of a headlamp as people generally believe. Not that it's unimportant, but beam pattern is extremely important. A bright lamp with bad optics is much worse than a not-so-bright lamp with good optics.
It's hard to predict what the beam pattern you'd get with this frankenstein setup, but it's hard to imagine it being good.

If you really want to see better at night, you may consider looking for a pair of Hella XL auxiliary lights. They're discontinued but show up on eBay for as little as 50 bucks (sometimes they're not even used). These aren't fog lights or driving lights; they're auxiliary low beams, 50-state legal. They'll probably help a lot.

The best alternative would probably be to get LHD European lamps, but it's not clear that that's at all possible, and would certainly be hugely expensive. But the European beam pattern is far superior to the DOT-spec pattern on 90-91 USDM Legacies.

georryan · Post by **georryan** » Sun Sep 14, 2003 5:05 pm

Thanks for the tip. The reason I asked was that there was some 9007's on sale on ebay for almost half price. They were used but the seller looked reputable enough, and he didn't have any negatives, or at least it was negligable. So, yeah, guess I won't buy those.

vrg3 · Post by **vrg3** » Sun Sep 14, 2003 6:10 pm

Yeah...

Oh, while we're somewhat on the topic, avoid the "HID look" bulbs... Avoid any bulbs with tinted coatings at all, since those definitely detract from the light output, especially the blue tints. Halogen light has a yellow tinge to it (which is beneficial, by the way), so to get a non-yellow color you have to reduce a lot of the light coming out of it.

http://www.topbulb.com has 9004 bulbs for $3.95 each. They also have 2357NA and 168 bulbs (that you could use when you do your corner light conversion) for $1.75 and $0.75 respectively. Shipping is fixed at $6.95 no matter how big your order is...

georryan · Post by **georryan** » Sun Sep 14, 2003 6:13 pm

cool. So,....those PIAA superwhites that are still in the yellow spectrum, (ie under 4000k) would be bad to get if they have any kind of tint on the glass of the bulbs?

-Ryan

vrg3 · Post by **vrg3** » Sun Sep 14, 2003 7:07 pm

Yes, they would be bad.

"Color temperature" doesn't really mean anything when evaluating how good headlights are. One day I'll get worked up enough to go on a long tirade of why.

But in simple terms: how can a tinted coating improve the amount of light the bulb puts out? It can't. What tinting does is remove certain portions of the spectral distribution of light. And a blue coating, in particular, removes the strongest part of the halogen light's output.

You have to be particularly skeptical of PIAA because of the claim "45/65w = 85/110w." That's simply not possible. They hurt their own credibility, while at the same time insulting customers, by making such claims. A "whiter" color does not translate to better vision or more luminance. All it translates to is relatively more stimulation to the short-wavelength cones on your retina and relatively less to the medium- and long-wavelength cones.

In any case, blue light is bad for automotive use. You can search for other posts where I've covered the reasons.

LaureltheQueen · Post by **LaureltheQueen** » Mon Sep 15, 2003 6:06 am

You may want to consider sylvania silverstars, they make 9004 bulbs, and all my friends who've gotten them absolutely love them

vrg3 · Post by **vrg3** » Mon Sep 15, 2003 3:58 pm

No! The Silverstars have a blue coating on them to change their color!

In order to reach a reasonable level of light, Sylvania uses an extra-thin filament (the kind you'd see in a lower-voltage bulb) so it'll burn hotter. That translates to much shorter bulb life.

The coating removes some of the yellow, so that the relative amount of blue increases. Like I've said before, more blue is a bad thing in automotive lights. Blue scatters more than yellow in our atmosphere, causing glare. Our eyes' short-wavelength retinal receptors (which are the ones sensitive to blue) aren't even in the imaging plane of the retina, so it's impossible for our eyes to focus properly on the blue component of a scene.

Silverstars were designed as a competitor to the PIAA Superwhites. They're perhaps not as bad due to the overdriven filament, but they're still not as good as a real bulb.

Sylvania does make a true performance bulb, though. The Xtravision line of bulbs are actually better than standard halogen bulbs. They have a more efficient design so they do emit a bit more luminance and actually last longer at the same time. Not to the degree their advertising claims, of course, but we already know that we can't believe a word of their advertising anyway...

Whether it's worth the premium is up to you...

By the way -- I've mentioned this before, too -- if you're still using the stock BC/BF headlamp wiring, you would do well to put in a new headlamp wiring circuit where the stock wiring triggers relays that power the lights directly from the battery. The stock wiring, especially when 9 to 13 years old, doesn't carry headlamp current very well. Better wiring will increase the brightness of your lamps (even with stock bulbs) measurably and noticeably.

czo79 · Post by **czo79** » Mon Sep 15, 2003 6:32 pm

Although I understand the technical details of why PIAA superwhites aren't a good idea...I have used them in several cars...and have always found them to be quite an improvment, with a few caveats...I use the ones that are just really white...make normal halogen look yellow, not the ones that look actually blue or purple. I understand that these still have a coating, but I don't think its to as much of a degree. Anyways, in normal driving, I find them to be quite a bit brighter than whatever bulbs I have replaced them with. My understanding is different bulbs can create different "hot spots" of light and patterns of diffusion with the same reflectors. I guess maybe the PIAA's pattern works well with the subaru reflectors? Cause there seems to be more light where I want it. The other large advantage I find is that due to the increase in the blue part of the spectrum (i think), which scatters more, I find the PIAAs have an amazing ability to "set off" reflective surfaces from a great distance, much farther than the bulb appears to light the road. So things like roadsigns, road, car, and bike reflectors, and maybe most important to me, animal eyes, glow from a long distance away, giving me more warning time. However, I do find the piaa superwhites to have significantly impaired performance in foggy/misty, rainy, and snowy conditions. This is also due to the blue's scattering nature. My solution has been to "warm" it up with a set of amber fogs. Works ok. I would prefer a quad headlight setup, with a superwhite high and a amber/yellow low. Anyways...this is just my experience and opinion.
Micum

evolutionmovement · Post by **evolutionmovement** » Mon Sep 15, 2003 10:04 pm

Do not get the Sylvania Superwhites! I, ahem, used to work for OSRAM Sylvania and heard they had trouble with those, although as part of full disclosure, I worked in the QA for flourescent ballasts, so only heard this second hand from engineering. I figure with all the alternatives out there, why take a chance anyway.

I've had good luck with the regular Sylvania bulbs and rarely have to use the high beams. Of course I also have two 55W yellow Hella fog lights over the bumper...

Steve

91White-T · Post by **91White-T** » Tue Sep 16, 2003 1:07 am

I got 9004 blue tinited bulbs, and I must say the visibility is 11ty billion times better than before not to mention how much better it looks...

vrg3 · Post by **vrg3** » Tue Sep 16, 2003 8:57 am

Let me start by saying that I'm not trying to be argumentative. I'm not trying to be rude. I'm not trying to insult anyone. I'm just trying to make sure that we all share our knowledge, and I do believe I have some to share here.

Having less tint is better than having more tint, but it's still bad, because it's still subtracting light. A halogen bulb emitting "white" light is only possible with a blue tint which offsets the yellowish color of the actual light being produced. Realize that there is a tolerance in legal luminous output of any given type of bulb (like plus or minus 15%). Any legal bulb with a blue tint starts off as a good bulb (on the high side of the tolerance) which is then crippled with the tint (bringing to the low side of the tolerance, but still legal). The Sylvania Xtravision is essentially the Silverstar but without that light-robbing coating.

It's important to realize that the human visual system is a very complicated thing in which the brain (and attention, controlled by the brain) plays a huge role. The scientifically correct way to measure the light output of a bulb-and-headlamp combination is with a photogoniometer that measures luminous flux over a wide range of angles. Realize that subjective perceptions don't necessarily mean so much; you can easily think you see better when you don't, especially if you've shelled out $30 and the only way to justify it is that you can see better. Think about it -- if you concentrate, you could see obstructions in the road and animals off the side of the road with a 20-watt flashlight. That same flashlight can reflect off reflective signs pretty well too... You can see these things because you look for them. But when you're driving, and your eyes are constantly performing both scotopic (low-light, rod-based) and photopic (high-light, cone-based) vision, it's much more complicated than that. These bulbs aren't really helping you see further. The exaggerated blue component actually makes it harder to focus and judge distance.

It's kind of an odd situation when the tool through which we experience and use something is incapable of properly measuring it.

Micum, you kind of have a point with the idea that different bulbs can create different beam patterns. But, that's only when the bulbs are not manufactured to proper specifications. All proper 9004 bulbs will give you the same correct beam pattern with your headlight. Some of the marketing-inspired (as opposed to engineering-inspired) bulbs have the filament in the wrong place so the hot spot gets brighter at the expense of the periphery; the brighter hot spot is where some of this "100 watts of output from a 55 watt bulb!" nonsense comes from. I don't know for sure if the PIAA Superwhites in particular do this. (Something in the back of my mind wants to say they used to but had to stop since it was illegal, but I don't know that to be true.)

You're absolutely right about the problem with bad weather. Be careful about trying to use yellow fog lamps as a band-aid. You're on the right track with the color, but the beam pattern of a fog lamp cannot illuminate the way a headlamp needs to. You put yourself in a dangerous situation when your lighting makes you believe you can see better than you actually can.

There's no question that the stock bulbs aren't very good... almost any aftermarket bulb will be an improvement. But some will be much better than others.

And let's not forget our responsibility to other drivers... Bluer light is harder for human night vision to recover from, and has higher saliency than yellower light, so the eye is involuntarily attracted to it. Come on, guys... We're Legacy owners. We're more mature than those "I put driving lights (which are meant to be auxiliary high beams) on instead of fog lights and I know they're good because everyone flashes me because I'm blinding them so they work great with my JDM lights that I epoxied HID capsules into because blue looks so cool" kids.

Seriously... just get some Xtravisions and call it a day. If you need more, get something that actually gives you more, like Hella XLs. Other than that, you can't really do much with the lousy headlamps Subaru equipped 1990-1991 US-market Legacies with.

91White-T · Post by **91White-T** » Tue Sep 16, 2003 2:49 pm

Not trying to be a jackass but don't you think you overanalyzing the issue just a little bit? ...I mean its just headlight bulbs, not really all that important

Post by **Legacy777** » Tue Sep 16, 2003 4:47 pm

91White-T wrote:Not trying to be a jackass but don't you think you overanalyzing the issue just a little bit? ...I mean its just headlight bulbs, not really all that important

Last time i checked....seeing/visibility was a pretty big componant of driving.

I'm not getting into the whole discussion. I've done my previous homework on the issue. I know what it says.....but I still have a slight tint on my bulbs. They are more silverish then anything, because I got them before everyone and their mother wanted them. Why do I keep running them? Because I don't feel like replacing a perfectly good working bulb. Plus mine are 80/100w jobbers.

91White-T · Post by **91White-T** » Tue Sep 16, 2003 5:23 pm

Let me rephrase.... The CHOICE of headlight bulbs isnt really all that important, as long as they light the road in front of you

vrg3 · Post by **vrg3** » Tue Sep 16, 2003 6:58 pm

I don't think any of us is trying to be a jackass.

It's important to realize that headlamps do a lot more than just "light the road in front of you." The type of beam pattern and the type of light is hugely important. You need to be able to see well in varying conditions and in varying directions; you need to make sure that your lights make your car easily visible in all conditions; you need to control the amount of glare your lights present to other drivers (who do have the potential to kill you if they lose control); you need to stay legal (or close enough to legal that you don't get stopped and ticketed all the time). Ideally you'd also want to not have to replace your lights every few months, and not have them burn more electricity than they need to. Automotive lighting deserves a lot more respect than it's usually given; a lot of engineering and science goes into good headlamp design.

There are plenty of people who think "any car is fine, as long as it has four wheels and an engine of some type." But to those of us who understand cars better, we know that there's much more to making a car safe, reliable, and capable. They are thoroughly engineered machines. So it is with lighting.

I think I've said enough; unless someone has some interesting new facts to bring to the conversation, I don't want to get worked up in an argument. I'm offering advice, and everyone is free to take it or leave it. We live in different environments with different requirements, and we all have personal preferences... just make an educated choice.

entirelyturbo · Post by **entirelyturbo** » Tue Sep 16, 2003 7:34 pm

I'm going to side with vrg3 on this. I had

umm... APC

80/100 blue bulbs in my car for a while. Although I thought the color looked cool, I decided to return my car to stock, I put the regular GE lights back in, and, well, I could actually see better...

And no it's not an insignificant issue. As Josh said very blatantly, seeing is an important part of driving. When I'm going down a dark highway in the rain, and a large animal is wandering on the side of the road, I would like to be able to see it if it were to enter my path...

That's why I really want to clean up my yellow headlights, and now, thankfully that I have another car (with EXCELLENT lighting BTW), I can take the headlights out completely and do a proper job per Josh's writeup...

vrg3 · Post by **vrg3** » Tue Sep 16, 2003 8:56 pm

subyluvr2212, you're lucky with the XT... It has H6054-type sealed beams so you can do pretty much anything with them. There are some decent sealed beams out there and some terrible ones; I guess you're lucky enough to have decent ones.

But, really, you know what you should try? Get some nice E-code lamps that are drop-in replacements. The beam pattern will be awesome. They respond very well to overwattage bulbs, too because the increased light doesn't increase glare (unlike most US-spec lights), and the good ones have glass lenses and metal reflectors.

Cibie ones are supposed to be the best, but they're more expensive than most. But with a strong wiring harness with relays and some 90/100 bulbs, you'll be able to see better than almost any other car on the road, even when weather is bad, while still causing less glare than most US-spec cars!

Oh, and by the way, Sylvania makes the Xtravision in H6054 format, too, if you want a cheaper, DOT-spec, option...

Maybe these? http://cgi.ebay.com/ebaymotors/ws/eBayI ... 2432422230

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Are 9004 and 9007 lights interchangeable?

Are 9004 and 9007 lights interchangeable?