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Thread: A few(many) headlight engineering questions. Also help upgrading two carsí lights

  1. #1

    Lightbulb A few(many) headlight engineering questions. Also help upgrading two carsí lights

    Hello, Iím new to the forum and was hoping to learn a few things I couldnít find by searching

    So Iíve been reading anything and everything I find on the topic of headlights, but a few things are still not clear to me. I havenít gone to the point of subscribing to access research papers or buying textbooks, but Iím getting close. Hopefully posting a list of questions gets at least a few answered and my post isnít deleted...

    Small bit of background:

    • Currently shopping for an MR2 spyder
    • Hoping to get as much front lighting as I can because I like going on backroad spirited drives at night
    • Also hoping to improve headlights on our Ď06 Impreza due to its age


    My questions:

    • Iíll likely be putting in relay harnesses in both cars at some point with the help of my electrical engineer friend. I have a few questions on what to expect.
      • Whatís the best way to find out voltage drop at the headlights on my car? It appears to be lower than it should be, and Iím wondering if I should have it checked out before I put in a relay harness. The reasons I think itís lower is because the light output is quite weak and yellower than other halogen lights, frequently dims with almost any load, possibly after the voltage regulator died and I drove a few miles to get home while charging at 14-16V (which blew out a bulb and delivered the brightest halogen light Iíve ever seen out of the remaining headlight), and because there has been a rodent nest under the hood (cleaned out now)
      • In a car with older or weak wiring, is there any danger in putting in low gauge wiring for the headlights? As far as I understand it replaces the whole high current headlight circuit from battery to ground, except to use the stock wiring from the switch to activate the relay.
      • How much should I expect decent diy harness parts to cost for the impreza - 2x H7 lows, 2x 9005 highs?
      • How does a relay harness work in a mid engined car (battery in rear bay)? Iíve heard that it has some kind of terminals up front, but I donít know if it already has relays for the lights, nor what gauge wiring it uses for the headlights and for the run from the battery to the front terminals. Should I wait and see if the wiring is sufficient?
      • I can post a link if anyone wants to take a look at the 2000 MR2 Spyder wiring diagram for the headlights, although Iím shopping for the updated 2003+ which has H7 lows and 9005 highs, as well as fog lights. Might have to buy the service manual or a subscription to the online version and download as much as I can...

    • Interested in restoring the Impreza headlights because the car isnít worth much and I wonít be keeping it long enough to make new assemblies worth it
      • I have a polishing kit, and have done it before, but since I used the included headlight ďsealantĒ, itís oxidizing again after a year.
      • Iíve read about the methods, and was hoping for some up to date opinions
      • Thereís the easy to apply Opti-lens that seems to have good results, requires no special curing lamp or spraying, and has a long shelf life. Only cons are that itís said to apply quite thin and itís expensive.
      • Iíve read the spar varnish method, and the consensus later in that thread is that while it works, the clarity and durability arenít worthwhile, and it requires resealing once a year or two
      • Then thereís the GClear method. I remember coming across some similar alternatives, but didnít save them. This seems like one of the best options and a ďlifetimeĒ thing. Actually ends up being cheaper than the Opti-lens, but if there are cheaper versions of this, Iím listening. At 50$ itís still a great deal if itís a similar coating to the OEM UV coat. Only concern the the cost of the UV curing light. I canít find what kind of UV spectrum is needed, but polymerization in general seems to usually require a wavelength in the UVA spectrum. Would sunlight work? Otherwise, would a 365nm LED flashlight or curing lamp work or would I need a full UV spectrum high power light?
      • Last option is a two part clear coat, but Iím no professional, and donít know if I could apply it smoothly. Is there a way to do this well or a guide for doing this properly? Also, Iím assuming by the MSDS that Iíll need a full respirator, gloves, and goggles? Any info on what I should look for? Seems like a long term solution if done right, but the toxicity and my lack of spray painting experience is concerning.

    • I have a pretty good idea of what bulb upgrades to get, but I wanted to confirm a few things.
      • For the H7 low beams (on either car), Iím considering either the H7 Rallye or potentially the Philips XtremeVision or Racingvision.
      • I know that the flux of the rallye is significantly higher, yet it has longer life, but Iím curious if it has the same filament luminosity. If it puts out more light but at a warmer (~100-200K) temperature, I would assume thatís because it uses a larger, slightly cooler filament, right? Does that mean while overall output would go up, intensity around the center regions would not increase as much, or possibly be lower than the +XXX% bulbs?
      • Iíve seen a decent test (by ALR on Facebook - they take multiple lux measurements based on peak reading and a few points specified by FMVSS) that showed that an H9 bulb in two different H11 projectors exceeded glare measurements just above and to the right of center. Should I expect the H7 Rallye to do the same or is the H9 bulb more similar to an H7 than an H11 in terms of filament position and size?
      • Any opinions on the best 9011 bulb? I saw a comparison on HIDPlanet (I know, I know) that showed that a new Osram/Sylvania made in Korea HIR1 put out more output, and significantly more intensity than the other bulbs. It seems it also has a smaller, tighter filament, based on the close-ups of the bulbs. I can edit in a link if anyone wants to see that comparison.

    • Iíve read the few threads talking about auxiliary low beams, and none of them seem to be conclusively for it against them, so Iím still curious. I know I should wait and see if the upgraded lighting is sufficient, but weíre not on this forum because weíre happy with sufficient, right?
      • I was thinking about adding the Hella premium 90mm H9 bi-halogen lights into the similarly sized fog light mounts. Iím assuming this would be below the legal mounting points for low beams, even auxiliary ones?
      • From what little testing Iíve seen done on this, it does appear that the SAE version is a very good, high intensity light. User Hilldweller, on a Jeep forum, recommended them as the best halogen upgrade available for the 7Ē round housings.
      • The testing also seems to suggest that their beam profile is balanced towards the top of the beam. As in they put most of the intensity above the 1-2 degree mark, which, from what I remember about trigonometry, should put the light out between 40 and 180 feet, when mounted at what I estimated the height of the fog light housings. Would this still overlight the foreground?
      • So this is out of curiosity, not because I would do so, but given a low enough mounting height, wouldnít lights aimed level or just slightly up theoretically not cause glare? Even if they were aimed VOR at say .2 up, they wouldnít reach driver eye height for well over 100m, at which point they wouldnít produce more than 1lux anywhere in the beam? According to my calculator, with a 12Ē mounting height difference between the low beam and fog light mount, the top of the beam would only reach the height of the low beam headlight after 300 feet, at which point theyíre producing under 5 lux. Now like I said, I wouldnít aim any low beam lights above legal limits, but Iím curious if they would glare if they were.
      • I believe Iíve read that rigidity is a problem with bumper mounted lights, so is this a reason this kind of auxiliary beam is a bad idea? If they were to be secured to something more rigid, would it make a difference? If they were aimed significantly lower (and be mostly useless, I guess), would the flexibility of the mount still be a problem?
      • So Iíve read all the concerns about the uselessness of fog lights. Given this, and since the bi-halogen lights are as cheap as 150$ for pair, would using them as independent fog lights mounted quite low be at all useful? Since theyíre full compliant low beams, and if I were to wire them to work without the low beam on, could they function as fog-only lights?
      • Or, could I use the bi-halogens fixed in high beam, or use the 90mm performance halogen high beam as auxiliary driving lights? Still too low for this function?
      • What if i angle them a tiny bit outward for a broader beam pattern as static cornering lights? I guess Iíd have to lower the driver side to have the right side cutoff be under the VOL aim height, but otherwise it could be helpful. I believe Iíve even seen a similar suggestion from one of the mods in an aux low beam thread.

    • Iíve been spoiled by the AFS HID lights in my previous car, and have always been curious how they work and if it is even remotely feasible to reproduce something like this.
      • As much as Iíd like to, Iím not suggesting retrofitting a rotating AFS system inside the headlight, plus controlling that system successfully via off the shelf parts sounds next to impossible.
      • My other idea is to use the 90mm bi-halogens as a fixed AFS system. Iíve read in a Valeo brochure about the mythical existence of a system in between rotating AFS headlights and <25mph fixed cornering lights. It uses some sort of outward mounted lights with a beam profile akin to low beams, and activates selectively based on cornering.
      • Iíve seen something similar suggested by one of the moderators, except using fog lamps with a similar beam profile to low beams facing outwards wired to come on with the turn signal. Not sure if my concept is similar enough or if it goes over the line...
      • If the 90mm projectors were mounted pointing outward at the angle suggested by Valeo (somewhere between 15 and 30 degrees), and used something like the Hella Dynaview control module to switch on based on steering angle and yaw rate, and then switch off on a timer, I believe they could work as fixed curve-adaptive lights.
      • What are the regulations on curve-adaptive lights, and how impractical or non-compliant would my idea be? Would it be better if they were 90mm fog lights, but preferably ones with slightly more distance than the usual junk? Is operation of these kinds of fixed lights illegal above a certain speed?
      • Would the regular 90mm Hella Dynaview Evo2 cornering lights be at all useful outside of intersections? I know they only function under 25mph, so that rules out all but the slowest curvy roads. Is this limit based on any US regulations? Would raising it slightly, to say 30-40mph, harm my vision at all on dark curvy backroads? Obviously the beam pattern is part of the limit, but at slightly higher speeds than 25, wouldnít any light that shines on the inside curve ahead be useful given that the headlights are still pointing to the outside shoulder?

    • I know Daniel Stern suggests moving the DRL function to a different unused front light (canít remember if itís the turn signal, front marker, or parking lights), and Iím interested in this to preserve the lifespan of the low and high beams.
      • For some reason the Subaru uses the low beams as DRLs, so in my opinion even using the high beams at lower voltage would be an improvement. It also has seemingly useless parking lights that only function to drain the battery if you accidentally hit the switch on top of the steering column. What would be the best solution that would maintain DRL function?
      • I donít know exactly what the DRL system is on the Spyder, but I know the facelifted headlights have a parking light and a turn signal at least. Does anyone know what the best option for that car would be?

    • With the MR2 Spyder, Iím lucky to get two compatible headlight options in case I need or want to replace them.
      • I would likely replace them given the terrible oxidation on most of the cars Iíve checked out. Even if they were in fine shape and could be restored, I could get slightly better performance with new ones, and I would have the option to choose the other type of light with a different optical system if it were better
      • So Iím curious which light would be better. The early headlight is a large H4 reflector, and the update uses an H7 low beam projector with a 2.5Ē lens and a 9005 high beam reflector
      • Anecdotally and via general info about reflectors versus projectors leads me to think the projector would be better, and it has the benefit of using both beams on high. They are 500$ a pair though.
      • Given the size of the headlight and reflector, I have a suspicion the H4 reflector can perform pretty well. It also has the benefits of having many high performance and overwattage bulbs available, as well as being 150$ per new assembly.
      • But I have absolutely no firm information of any kind. No one has tested these (publicly), no one has even compared these with a luxmeter or even with wall shots. Even the recommendations on forums merely say the facelifted lights are much better, but donít even go into detail about the beam pattern or performance on the road. I guess thatís the downside of a rare platform. Miatas have no end to forum posts about minute specifics and some pretty technical information (and you know, the 7Ē sealed beam and all the options for that).
      • With a low gauge wiring harness, the best bulbs, and new or restored headlight housings, what kind of light output, beam distribution, and performance should I expect? Are lights engineered 20 years ago comparable to modern halogen lights? Lower end LED lights? Would they tend to have more distance visibility or a wide output? Any info or even impressions would be helpful.

    • Thereís not much good info about halogen bulbs. I suppose thereís not much about HID capsules either, but when every crappy LED ďbulbĒ maker publishes (admittedly inaccurate) detailed specifications on their products, the halogen bulbs seem even less described by comparison. Most of the time all you get is a +XX% vision and thatís it, and only niche forums ever test them to find out if the claims are true, and even then itís often only peak readings. So I have a few questions I havenít been able to find the answers to.
      • Iíve seen Daniel Sternís bulb chart with the flux outputs, and find it helpful to refer to whenever Iím researching specifics. But it is still very general information, and thereís no specifics about rated bulb lifespan, rated flux by brand or performance line, filament dimensions, capsule dimensions and pressure, etc.
      • As far as I know, those features are what determine the actual intensity increases in a headlamp, due to higher luminance and a smaller filament approximating a point source better. Is there anywhere to find this kind of information or is it all proprietary?
      • Also, is it safe to generally assume that increasing any one of the factors will improve output: increasing flux with no other changes will get more intensity everywhere in the beam; increased (native, uncoated) bulb color temperature means a higher filament temperature and higher luminance; smaller filament means more luminance and higher peak intensity; smaller capsule and higher pressure means higher filament temperature, color, luminance, and peak intensity?
      • How do bulbs compare to each other. I assume that besides the single/dual filament and axial/straight bases, there are other considerations by which manufacturers choose their output source. Given that an H7 is newer and has a higher rated flux than say an H4, does that mean the technology and performance are better by definition?
      • Also, given the ability to create high flux bulbs like the HIR1 (the modern, non infrared reflective ones) or H9, is the only thing stopping lighting manufacturers from building higher flux and luminance versions of other bulbs the bulb ratings for compliance, and not technological limitations or compromises?
      • If the above is true and the limit is legality, how come bulb manufacturers donít create high performance ďoff-roadĒ bulbs with the exception of the H7 Rallye and maybe the H7 RacingVision (which I think is only compliant in certain countries). Clearly there is no issue with building overwattage bulbs, and most people actually researching such upgrades wouldnít mind the technical non-compliance if given a safe-ish significant increase in intensity and flux.

    • So the other half I donít understand and canít find many resources on is the headlamps itself, as well as the optics involved.
      • Iím a regular on BLF and redditís r/flashlight, so I know about the basics of reflectors, TIRs, and aspherics, as well as their optical efficiency, approximate amount of light collected and how well itís colimated, and the correlation between optic diameter (and depth to a smaller extent) and its ability to produce higher candela values.
      • I just donít know quite how to apply it to headlights. Iíve found Hellaís page that says free-form reflector optics capture as much as 45% of the source light, and then only 90% is actually reflected, and 85% passes through the headlamp cover. Similarly, I believe the numbers for projector optics (in high beam I believe) are 52% of the light captured, but an additional amount lost since the aspheric lens only allows 90% or so through.
      • Now if those numbers are anywhere near accurate or universal, all that addresses is the amount of flux that actually is directed onto the road. How intensity is distributed is another question. Iíve seen the diagrams and ray tracing images of what areas of each type of optic deliver generally which section of the beam pattern, but I have no clue what kind of differences in design affect the final beam. Is there anywhere I can find this out, or a general explanation of what constitutes a ďgoodĒ, broad, or high intensity headlight optic.
      • One thing I learned that was interesting and super obvious after the fact is that since projectors output the same intensity as reflectors through a smaller area, they appear much brighter when viewing the lamp from the front than reflectors, even if they deliver the same intensity in a certain point.

    • Iím curious what the consensus (or lack thereof) is on the best beam pattern for driving, beyond decades old compliance test point minimums.
      • Daniel Sternís paper on glare mentioned that while generally bad for distance vision, when people use their fog lights for foreground lighting, they tend to keep their vision up and looking further due to the feeling of security. Given how many people drive like this, is there any validity to this concept and would a larger, but still balanced, amount of foreground light be potentially helpful to average drivers?
      • In addition to the above, given how many people drive around other cars, and given the increase in glare, is it worth trying avoid dilation of the pupil in response to foreground light if itís likely happening a lot anyway in response to the glare? I know itís hard to keep looking at the distance when every few seconds I have to slow down, stare at the shoulder line, and hope I donít die because an LED equipped truck or SUV is passing by? I know an arms race of brightness isnít ideal, but if itís already happening, wouldnít a proportionally brighter foreground and distance be valuable? And isnít this the idea behind the ďtown beamsĒ on European ADB systems?
      • Iíve read a decent article by a lighting engineer about the ideal gradient of light for visibility. Itís basically increasing the candela value exponentially compared to distance, to keep the illuminance of the road consistent. Does that sound like the optimal beam pattern or should it still be balanced to be perceptually brighter in the distance?
      • In my personal opinion, the top 1 degree of the beam is most important, especially on low cars because it determines distance vision. Given that most cars provide more than adequate brightness in the foreground and between 1-2 degrees down, in the near-but-not-foreground area, why isnít there more focus on increasing intensity past 100 feet or so, depending on aim and mounting height. Especially with the increased speed limits since the regulations were set.
      • Are there any kind of headlamp optic, or manufacturer, or even aftermarket part that can increase the intensity near the top of the beam, even if it comes at the expense of light closer to the car?

    • Where to find resources for research. Iíve read just about everything I could find by Daniel stern, Iíve browsed through half the threads in this forum, gone down multiple Wikipedia optics/light article and US regulatory document rabbit holes, and filled up my google search history with headlight related queries.
      • Still, I see people throwing out information like itís common knowledge, and I have no clue where they get that.
      • For example, Iíve found, and bookmarked or saved a few photometric reports on some headlight assemblies, but theyíre mostly SAE samples of 20 year old cars, Daniel Sternís isolux plots of various sealed beam replacements, a few failed tests demonstrating over and over how bad HIDs are in reflector headlights, and two tests on recent Morimoto projectors.
      • But people here and in other forums talk about test results for a bunch of specific headlamps, although rarely reveal them. I know there must be copyright restrictions on this data, but how do certain people have access to these, and is there a way for me to do so without submitting a few hundred headlamps to Calcoast or bribing an automotive lighting engineer?
      • Is there also general headlight engineering knowledge Iím unaware of? I see people here and lighting engineers discussing how a light should perform, based on just seeing a picture of the light.
      • For example, the Tacomaworld poster linked in a sticky mentioned how the large H4 reflector in his truck should outperform the H11 projector in the next generation. Based on what Iíve been able to find, in this case, Hellaís tech articles on headlamp systems, low beam projectors capture more light for the beam than reflectors. Plus an H9 produces more flux than even a high wattage H4 low beam (in this example). I know also that thereís more optical efficiency loss with the projector given the addition aspheric lens it passes through. But how can one actually take an educated guess at what kind of performance a headlamp should produce?
      • Another example is a thread here, in which Virgil mentioned how the larger high beam reflector in the 2002 camry headlamp, even with its non-round shape, should outperform the 2006 headlamp with its smaller diameter high beam. And later in that thread, he mentioned that for the 2000 camry, the (still compatible) European spec H4 headlamp is better optically than the identically sized US version. Is this based on photometric tests I donít have access to? Is this an educated guess based on optical factors Iím not aware of? Or did I miss something in that thread that explained why one is better than the other.
      • Iíve read about (for example), the different methods available for designing a freeform multi-faceted reflector headlight. And the engineering and software behind it is incredible. But while itís nice to know the different methods that can be used to create the shape and location of the reflector segments, but I canít apply this to any real headlights because I have no way of knowing what method was used. I donít know of a way to determine which method was used to design a certain complex reflector, nor what attributes contribute to its performance beyond perhaps its size.

    • Headlight retrofits
      • The forum sticky and Daniel Stern say that theoretically they could be done well, but itís harder than itĎs describes. I agree that most retrofits are low quality, and usually tend to be worse in terms of performance (the Morimoto Mini H1 projector test is hilariously bad compared to what people say about it).
      • Iíll start by saying that while Iíve spent a fair amount of time (for lack of better information) researching a retrofit, given the difficulty of doing it properly and the performance I could theoretically achieve with the stock lights and possibly auxiliary/cornering lights, Iím not planning on a retrofit. If I were, I would definitely consider all the concerns raised here before even thinking about starting anything. So, Iím hoping this means I can discuss this as a concept, and not as a request for guidance. Itís also because Iím curious about this topic having read a fair amount about it, and since the sticky post doesnít answer all my questions on the problems with retrofitting headlights.
      • Given photometric simulations of a projector (for example the M LED 2.0, which is the only one I have relatively complete data on), and assuming a 15% cover lens absorption, what other factors can make the resulting output non-compliant?
      • By the way, I followed the launch of the M LED 2.0 pretty closely and Iím curious what peopleís thoughts are on it. Thereís instructions to make it pass the .86D, 3.5L maximum as well as to provide more light above the cutoff. While I donít agree with the choices, nor the color temperature and cutoff sharpness, those non-compliant test points were designed on purpose to appeal to peopleís subjective impressions. Besides those (fixable) test points, and given the comparative breadth of information available about it compared to pretty much any other OEM or aftermarket projectors, I donít see what would make it an unsafe and ineffective lighting solution.
      • What about OEM projectors, such as the great Koito Bi-LED (both anecdotally, in a test for which the numbers are not available to me, and in the IIHSís tests). They perform well even with cover lenses, and the lenses on the Spyder are not a very complex shape. Beyond some chromatic aberration, wouldnít the refraction enter and exit the lens at the same angle? Even if it didnít, as long as the shift from refraction was consistent through the beam pattern, couldnít the shift be adjusted by reaiming?
      • I understand the issue with the mounting method most people use - cutting out parts of the reflector and epoxying the projector into it is not a good solution for something that has to be so stable. Based on some images of an opened headlight that Iíve seen, the Spyderís projector is part of a bracket to mounts properly. Given this, wouldnít removing the projector parts and attaching a new projector to the remaining brackets be as secure as the original, and it could maintain the aim and vertical/horizontal location?
      • I know why you blanket ban retrofits, although I personally think discussion and information on the topic would be more persuasive than just having every post questioning it deleted. Itís not my forum, but I do find I appreciate when ďthere are no stupid questionsĒ, because we all had to start somewhere. Without much available information, it took a long time and a lot of research to get to the point of understanding I have now, which apparently is just enough to understand that upgrading the stock lights safely is the best I can reasonably do.
      • Iíve seen how most retrofits are performed, but is there no way to perform one well without industrial tools and manufacturing? If mounted securely and with respect to center of mass, sealed properly, using an OEM projector that complies with photometric regulations, the end result aimed properly, and then the ~20 test points verified with a full spectrum lux-meter at 25í (particularly the glare points), would this still be unsafe?

    • This (among other things) might get my post deleted, but Iím curious why certain halogen upgrades are allowed, since any discussion of illegal or non-compliant upgrades seems to be against the rules. Iím pretty sure HIR upgrades, Rallye bulbs, and overwattage lights arenít exactly road legal...



    This turned out incredibly long. Sorry about that. I could break it up if needed, or pare it down if needed.

    Thanks. Hope I get to learn something and make good decisions once I get my hands on some upgrades.
    Last edited by Alaric Darconville; 07-09-2020 at 07:30 AM. Reason: Removed COLOR/FONT tagging

  2. #2

    Default Re: A few(many) headlight engineering questions. Also help upgrading two carsí lights

    Welcome to the board. Wow! You came close to 5000 words, not including your introduction. That might be a record. Some of your questions are practically answerable on the forum; others are more appropriate to ask a vehicle lighting engineer or consultant on a one-on-one basis.

    I will try to answer as many of your questions as I can; others may speak up with answers to other questions or other answers to these same ones:

    There is a section on how to measure headlamp circuit voltage loss on Daniel Stern's relay page here. Adding relays to a late-model car is often not as simple or consequence-free as on past models, because of factors that didn't used to exist (DRLs with modified headlamp operation, PWM operation of headlamps, self-diagnostic capabilities with circuit shutdown in the event of a detected fault, etc).

    Headlamp "restoration", even with a hard coat or sealer, at its best is a temporary way of bringing the headlamps back from being completely unsafe, for awhile while you save up for new headlamps. It does not restore the lenses to like-new condition, and it does not address reflector deterioration (which is especially an issue in projectors). Reflectors can be refurbished. That site's in German, but spend some time clicking around in the galleries -- they do really nice work. Of course, it's often more cost-effective to just buy a new headlamp, if one is available.

    The H4 is an archaic bulb from the late 60s. The best current versions of it are definitely better than the originals, but the inherent technical limitations of this very old bulb still remain. Chiefly, the inherent inefficiency on low beam. Because H4 has a shield below the low beam filament, at least 45% of the total reflector area is not available to magnify the filament's light. Basically you are cutting the effective size of the headlamp in half on low beam. There are also internal reflections that cause stray light which has to be dealt with optically, which can take away from beam performance. This doesn't mean an H4 headlamp is necessarily bad, and in a reflector system with a 2-filament bulb providing both beams there is some advantage to reserving a portion of the reflector exclusively for high beam, but the fact remains it is hard to get really good low beam performance from an H4 headlamp unless it is truly enormous (like, final-design Volvo 240, or some of the huge Toyota truck lamps).

    On your MR2 the H7 projector/HB3 reflector lamp assemblies are going to give vastly superior performance to the H4s, even if you Compare a high-perf H4 bulb versus standard H7 and HB3 bulbs, and the H7/HB3 lamps are going to be much more effectively upgradable. Guesses and wishes to the contrary by some guy on a truck forum are good for a laugh, but he's welcome to keep dreaming on if it will make him feel better! (that answer applies if you are comparing real (OEM/genuine) headlamps to real headlamps...off-brand aftermarket junk doesn't rank, and if the comparison is genuine H4 headlamps vs. aftermarket H7/HB3, that gets to be a harder answer, probably in favor of the OEM H4.)

    Put your money and sweat into the best possible headlamps before even starting to think of auxiliaries. Yes, a Hella 90mm is much too heavy and aim-critical to mount on a flexy bumper cover; it needs a truly rigid support. And yes, they will overlight the foreground. Also VOR headlamps are not supposed to be aimed up above horizontal. And driving lights (properly, auxiliary high beams) are counterproductive and pointless mounted down low.

    Discussion of certain bulb upgrades are allowed here, even while others aren't, because the "allowed" upgrades work safely in a big enough number of applications that it wouldn't be accurate to say "No, that's unsafe". At the same time, it also wouldn't be accurate to say "Yes, that's perfectly safe". The "not allowed" upgrades are UNsafe in all (or at least almost all) cases.

    The 65w H7 bulb is head-and-shoulders-and-bellybutton above any of the 55w high-output H7s: much greater flux (lumens) with equally high luminance (not "luminosity"). The 65w H7 is an H9 with an H7 base, and H9 is, by design, a high-luminance bulb design. You might be interested to read this thread.

    I saw that comparison test of the various 9011 bulbs on HIDP, too. I don't have much to gripe about with respect to the methodology, except that same old bugaboo that makes really meaningful tests tedious and expensive: too small of a sample size. n=1 means you're testing this individual bulb versus that individual bulb, not this kind of bulb versus that kind of bulb. I'm holding judgment on the Korean 9011 bulbs. The ones I scrutinized and measured did not match up to the performance benchmark set by the Toshibas, largely because of filament positioning issues, but it's a fairly good guess that when I look again at another batch of them in six months or so they will have improved a lot -- that is a pattern: some very good bulbs are made in Korea, but it often takes awhile for the production quality to ramp up. For now the Toshiba bulbs are best-in-class. Expensive to buy through the Toyota parts system (see here) but Dan Stern has some quantity of them for less than half that price, or at least he did awhile ago.

    Speaking of testing, be careful what you fall for. Photos of fancy equipment, and colorful graphs, and nicely-designed charts, and technical terms can represent bad data just as well as they can represent good data. The kid behind those ALR "tests" (I think he is also the keeper of the "Bulb Facts" website) is certainly an eager beaver, and he does know quite a bit, and he appears to be gradually learning more, but there are still major, major holes in his knowledge and understanding. Some of the holes are empty (and big enough to drive a VW into), and some of the holes he has filled with nonsense. All of it, he wraps up and presents as if it was factual scientific data. That makes it difficult to pick out the wheat from the chaff. He also has some imaginative but ungrounded pet theories and ideas that he really, really wants to be true, and they tend to get baked into his "tests".

    Your idea to build/cobble a sort of semiautomatic curve light system sounds good, in theory. The 25mph limit on cornering light function is in ECE Regulations, not US/Canada regs, but you still have to bear in mind where the light is going and whether there are going to be other drivers' eyes in that area. On the other hand, if you intend to use this system with high beams, then there's not really a reason to have it be steering-responsive; you could just leave the curve lights on. Effectively they'd be wide-angle auxiliary high beams.


    Projector retrofits are covered (including the factors that can make the result noncompliant) here. As for the M LED 2.0: as you acknowledge, it is a noncompliant product designed to appeal to nincompoops who think their headlamps are fashion toys rather than life-safety equipment. That, together with the consistent track record of TRS/Morimoto, pretty much spoon-feeds the conclusion even if that conclusion is more along the lines of what you need rather than what you hope/wish/want. There are some very good OEM projectors, and as long as you get a real one (the market is awash in counterfeits put out by the likes of Morimoto-and-worse to squeeze money from the nincompoops I was just mentioning) and it can be mounted securely in place of a different projector, and you can do it without breaking the headlamp's original seal, and there are no new stray reflections or other issues created by mounting the new projector somewhere other than its intended home, and adequate airflow is provided to keep an LED projector cool, then you may be able to arrive at a good result. Most often, though, the claimed "good results" are more a result of the claimer not knowing/understanding what the faults are, or simply declaring that they don't exist or don't matter.

    Front position ("parking") lights cannot function as DRLs. The Stern DRL solution uses the front turn signals.

    There is no single answer to your questions about whether lights from 20 years ago are comparable to modern halogens, LEDs, etc. There have always been good, average, and poor headlamps. The range between the worst and best is larger now than it has ever been, because the worst have gotten worse and the best have gotten better.

    There is also no single answer to your question of what is the best beam pattern for driving. Too many variables to give a pat answer to that one. But the article you mention (can you link it?) describing an ideal pattern as increasing candela values as we move from the foreground toward the horizon is theoretically correct, and broadly in accordance with how headlight beam patterns are specified.

    Filament pitch, fill gas composition and pressure, and the other factors that influence halogen bulb performance are mostly proprietary. There is nothing stopping a maker from employing modern technology to improve the efficacy of bulbs. That is what has resulted in all of the improved versions of existing bulb types (+30, +50, +80...+120, +130, etc). There is very little demand for high-wattage bulbs, which aren't legal anywhere, so not much incentive for makers to spend any money developing them. Note that high-watt bulbs are not usually the upgrade people like to think they are. Look at the poor showing of the name-brand 100/90w bulb in this test compared to newer, more technological approaches to squeezing better performance out of an old bulb type. And plus, we are no longer in the age of headlamps with glass lenses and metal reflectors. Most of today's lamps designed for a 55w or 65w bulb will not tolerate an 80w, 90w, 100w bulb for long.

    Headlamp design factors (what optical tools were used, focal lengths, etc) are also proprietary and not of much value once the lamp has been designed and produced. Headlamp photometry is proprietary; if a person doesn't happen to have access to it via their work, the only way to get it is to buy a lamp and obtain the data either by paying for the test or by getting access to the necessary equipment to do the test.

    Glare and seeing in night driving is a very complex topic with many complex answers, some of which are not intuitive. See here for one thread that illustrates.

    As far as how to gain a body of knowledge, there are some good textbooks on the subject, such as this and this. There used to be a really good SAE compendium of papers, bound up in book form, that was of tremendous value in bulking up on knowledge of driver seeing, headlamp and bulb construction and performance, signal lights, etc. It went out of print some years ago. You might see if Stern still has any extra copies.

    (You got me beat...I only managed to reach a little over 1800 words, not including these!)
    Last edited by -Virgil-; 07-06-2020 at 08:51 PM.

  3. #3

    Default Re: A few(many) headlight engineering questions. Also help upgrading two carsí lights

    Wow, thanks, I really appreciate the thorough response and the that you took most of my questions and ideas seriously. Sorry about the length - I just compiled all my notes and questions into one post so I wouldnít be the main contributor to this sub forum for the next week. I also think I may have missed some editing errors.


    Most of this confirms what I thought already, although Iím disappointed that so much of the engineering behind headlamps is off limits to most people. Unfortunately Iím just a guy that likes bright lights and driving, so I donít think Iíll have access to a personal automotive engineer or a bunch of industry photometric reports. Iíll check with Daniel Stern about that SAE collection - thanks for the suggestion. I was planning on picking up a few things from his catalogue, and sending a similarly wordy (less so now) email of questions, so might as well.


    Iíll try to keep things organized and go in order through your response. I do have some new/additional questions though, unfortunately for you.


    About the voltage drop:

    • Iíll be aware of the complexity of modern cars, and see if I can find a wiring diagram to avoid breaking any functionality. This is something Iíll likely work on with my friend who is much more experienced in electrical systems than I am. I suppose Daniel Stern could also point me in the right direction for relay harness parts and wiring since he builds premade ones.
    • Was the MR2 question about mid engine wiring harnesses one of the questions youíre leaving up to the rest of the forum? I canít find a single thing on the topic, and Iíve even started searching Porsche forums for ideas



    Headlight restoration:

    • Iím definitely aware Iíll never recreate the lens and reflector performance of new lamp assemblies, but in the case of the Impreza, weíre not planning on keeping for that much longer, so restoring it to new is not a priority. Additionally, I caught the UV damage relatively early, so Iím not sure the reflector surfaces are too badly damaged. Itís just unfortunately I restored them but didnít know enough to protect them, which is why theyíre outside getting yellow and hazy again.
    • For the MR2, Iíll very likely buy new lights unless the lens is in excellent condition.
    • Based on this answer, Iím leaning towards something like the Opti-Lens. That way I can somewhat restore the Impreza lights and protect them for a year or two, and the use the coating as extra protection on the new MR2 headlight lenses. Did I understand your response correctly, and is this a decent idea?
    • Also, Iím curious how projectors are more susceptible to UV damage. I would have thought that the glass/plastic aspheric lens would protect the inside of the projector by absorbing whatever UV made it though the cover lens.



    For the H7 vs H4 response:

    • Thanks for the explanation, that makes sense and confirms what I thought about the H4 headlamp. Glad to know thereís a good option available for the Spyder. Iíll definitely be picking up new OEM facelift headlamps if the old ones have any damage.
    • It does look so happy (https://i.imgur.com/JTVTag8_d.jpg?ma...idelity=medium)with the round lights though
    • I guess what I was seeing from Hella (https://www.hella.com/techworld/us/T...eadlights-219/) was more accurate for a single source reflector lamp, such as the HB3 high beam. Am I understanding that correctly? Based on the FF reflector illustration in that link, I mistakenly thought a dual filament reflector lamp could still use the entire reflector surface, just with a compromised beam pattern. I must have been thinking of a different type of lamp.
    • By the way, thereís no magically better EUDM version of this headlamp that also has a glass cover lens, is there?
    • Also, the guy I was talking about (https://www.tacomaworld.com/threads/...or-hid.398066/) did take *a* measurement per bulb, so it wasnít completely subjective, but I was disappointed in his methodology. That said, he does have one of those ďhuge Toyota truck lampsĒ you mentioned in the next paragraph.
      • If heís actually a vehicle design engineer as his profile says, then thatís a pretty embarrassing oversight...

    • This is regarding a further down explanation of overwattage bulbs in the link you posted, but isnít testing the overly large filament 100/90W H4 bulb not the greatest illustration of overwattage bulbs? I know you said that test wasnít complete, but I would have been curious to see some of the ďmid-rangeĒ power bulbs, which appear to maintain a smaller filament size unlike the really high power one. Based on the ďtest resultsĒ in that forum, Iíd be curious to see your measurements of the stated top performance bulbs such as the Osram 85/80W versions.
    • Since I seem to have combined this section of the response with the other bulb section, I have another question about that. Is there a story about why Osram ever built the H7 Rallye? It seem like a unique production by the way you describe it.
    • Thanks for the recommendations on the bulbs. Iíll be sure to get the H7 Rallye and ask D. Stern about the Toshiba 9011s. By the way, how much would the 10$ Wagner 9011s perform with a stock wiring harness by comparison (in case I want to try them in the Impreza as soon as this week)?



    The Hella 90mm projectors I was interested in:

    • Iíll definitely start with other upgrades.
    • I figured rigidity might be a problem. Is there no aiming strategy that could avoid glare? Or would reaiming increase the foreground over-illumination even further?
    • Would a more rigid mount, perhaps attaching to the body or subframe resolve this? I suppose that could mess with crash structures, but it canít be worse than tow hitches on unibody cars...
    • Before I completely give this idea up, how badly would the projector over-light the foreground? I believe the fog mounts are around 15-16Ē off the ground. Does this projector tend to have a bright foreground when mounted at a legal low beam height (24Ē)?
    • Also, my question about aiming the 90mm projectors was mistaken. I didnít actually know what aiming type those projectors are, and mixed up VOR aim, assuming that the right cutoff would have to be .4 degrees down.
    • In addition to the above, I found a response by you in an old thread that suggested (but not approved, I believe) that two-kink beam profile could theoretically be aimed VOL or VOR depending on the height of the ďstepĒ in order to increase seeing distance. I think this is what I misinterpreted in my original post. Would this sort of aiming help? From what Iíve seen, the SAE bi-halogen has a pretty significant step.
    • Also, out of curiosity, what kind of beam profile does that projector have? Itís unclear based on what Iíve seen except for reviews that that say it has good distance intensity.



    My question about the non-compliant bulbs on the forum:

    • I see what you mean about the average safety or success-rate of high output halogen bulbs compared to retrofitting projects. I didnít know that was the driving factor behind that rule.
    • Iíve also spent some more time going through the oldest threads in this forum today, and it seems there is a bit more flexibility in discussing that kind of thing provided people have an open mind. Iíve gotten a different impression in past visits to the forum, especially when looking up specific questions.





    About your warning on test results:

    • Then what can I trust? Thatís the mildly disappointing aspect of this forum - while the existing tests here are high quality and acknowledge their limitations, there just isnít many of them, so often times it seems your and Alaricís suggestions are just based on hidden data and information, despite the explanation. Not that I have a solution to this problem of course.
    • Iím curious what you think the problems with ALR/EVO88ís testing is. If itís the bulbfacts guy, heís definitely stepped up the setup from the single point reading in 2 different headlamp housings. And I swear Iíve seen EVO88 ****-talking bulbfacts....
    • What sources can I generally trust? At this point Iím down to IIHS test data and the few photometric reports Iíve found scattered around the Internet.



    Iím interested to hear more feedback on my static curve lighting concept.

    • Based on what you said about the Hella 90mm lights being too heavy for a bumper mount, I guess Iíd have to look for a different mounting system or different light.
    • To clear it up, Iím most interested in making it function as a curve supplementary low beam system, although I wrote out all the possible ideas I had to make a cornering light.
    • Iíll prioritize more important lighting upgrades before this, of course. Iím mostly just conceptualizing since I still havenít found a clean example of a Spyder I want to buy. COVID unfortunately seems to have raised used car prices, not lowered them.
    • Ideally I would have a stably mounted pair of the bi-halogen projectors pointed outward around 15-30 degrees based on existing AFS systems and a few studies I found on the usefulness of cornering lights (like this one: https://deepblue.lib.umich.edu/bitstream/handle/2027.42/85359/102757.pdf). Let me know if this is a hotlink - I donít feel super comfortable rehosting an .edu report.
    • Since they use a solenoid activated shield, I could use the as the wide auxilary high beams you mentioned if they came on with the high beam stalk. Or would they have to be activated separately in that situation? If I had to choose, Iíd rather have the extra light on low beam though.
    • Given the aiming and stability problems of the Hella projector in the fog light openings, I suppose thereís no aiming strategy that could avoid glare? Would a more rigid mount make this viable or would I have to look into an externally mounted cornering lamp or a lightweight lamp meant for fog housings?
    • Iím curious, especially in a right turn/curve, isnít the higher right cutoff of a regular low beam already crossing the glare points for oncoming drivers? And with AFS systems, doesnít the ďinsideĒ lamp turn towards oncoming cars? I suppose in standard low beam systems and true AFS, left curves arenít as much of a problem, but perhaps I could have the left ďcurveĒ lamp aimed lower, to the point that the right side cutoff is at the same level as the right lampís left side cutoff? Similar to how some staggered aimed headlamps were in the past (I think, I believe Iíve read of European 911s having their lights set up like this)
    • Would you be more likely to approve of this if I were to use something like a Hella Dynaview or Bosch fog light you recommend as an auxiliary low beam supplement?
    • What other considerations are there for glare in a corner adaptive lamp?



    About the projector retrofits:

    • I did happen to read through that sticky post, and the info you filled in helps me understand the additional factors I would have had to consider. I also found a post you wrote on a headlight retrofitting outfit (clearcorners) you actually respected, and reading their process was helpful. For example the commonly used (admittedly better than silicone) butulyl rubber sealant turns out to have issues as well.
    • One thing I wanted to ask about that ClearCorners mention on their page, was their insistence that crimped connectors were inferior to soldering and shrink wrap. I thought soldering was too fragile/rigid/inflexible for the vibrating car environment, and a good crimp was as good as you could get for an automotive wiring harness - is that wrong?
    • Either way, a retrofit project is off the table for me given the compromises and difficulty involved. Even as I was reading what the more ďexperiencedĒ retrofitters had to say, it kept sounding more complex and compromised. I do also enjoy the warm incandescent glow over the cool white LEDs.
    • I also remember the disappointment of finding out that all the TL-R, S2000-R, etc. ďOEMĒ projectors were actually replicas. Once I found the photometric reports (that were proudly posted by one of the owners), I think I started reconsidering what I had spent time researching.
    • I donít want to tell you what to do, but speaking as someone who fell for the marketing, I honestly think a side by side test report of the Morimoto mini H1 next to a sealed beam with a short explanation of what the test points mean would be a bigger deterrent to most would-be retrofitters than any wall of text. I can see if I can find that test report if youíre interested - although Iím not sure Iím permitted to share it.



    About comparing lights:

    • I realize itís difficult to compare lights, especially across so much time, and because thereís no definition of ďbetterĒ
    • That said, perhaps you know how the beam profile, width, and/or peak intensity of the MR2 Spyder compares to, say an NB2 (2001-2005) MX-5, which I happen to have owned and driven at night extensively.
    • How about an H7 projector from 2003 vs one from 2020? If there are any left. Has anything significantly improved, assuming the bulb and optic type are the same?



    The article about beam distribution:

    • https://betterautomotivelighting.com...-distribution/
    • I did omit the site it was posted on, and the fact that it was written by the chief engineer at Morimoto. That said, I donít see anything wrong with the content, although I take it with a grain of salt given the source
    • Side note, Iíve heard suspicions that the HID projector being compared in that article is their own MD2S, so Iím not surprised itís not named.



    Iíll see if anyone else has any more info about bulb technology and headlamp design.

    • I did have a question that I feel was unanswered. I mentioned in my post that I read a couple responses by you in this thread: https://www.candlepowerforums.com/vb...adlamp-upgrade
    • Iím curious how you made the judgements on what lamp would deliver better performance. Is this all just based on the pictures and bulbs used? I didnít know if you were referencing some kind of data that only you had access to, or if you were making educated guesses based on estimated reflector size, blacked out internals, and bulb types. In this example, Iím still not sure why the H7 lamp would be preferred over the 9006 USDM version, given the upgrades available to each. Iím interested in how youíre figuring this out I guess.
    • Similarly, while I understood your reasoning for recommending the H7 headlamp for the spyder over the H4, it still seems out of my reach to make such assumptions based on not much information. For example, how do you know the H7 projector will perform better than even the optically limited H4? Would the suggestion change if they were both single filament bulbs? What about if the H7 was lowered to 1000 lumens to match the H4? Sorry for the quizzing, Iím trying to learn how to figure this out.
    • Iíve seen this kind of response numerous times and itís always confounding how you make the call so definitively. If itís a trade secret, no problem



    As for the glare section:

    • Iím in agreement that glare is the unfortunate side effect of improved vision, and the improvements outweigh the glare, although ADB couldnít come soon enough.
    • Obviously, aim enforcement would be most helpful, but at least we have the IIHS trying to improve factory aim.
    • I was posting based off a short paragraph by Daniel stern that seemed to go against what he and everyone here says about using foglamps for foreground lighting. Iím referring to the ďFoglamps in clear weatherĒ section on pages 34-35: http://dsl.torque.net/images/DSL_8885.pdf (let me know if this is a bad hotlink, although I found this via google search so I wouldnít know where to link from properly...)
    • My uneducated thought was that perhaps increase foreground isnít as harmful as itís said to be, given how the main problem of it (pupil dilation), occurs when driving on busy roads, particularly in a low car. Nonetheless, I do think that even given this, distance lighting that is proportionally stronger than foreground is still important.



    Thanks again for the responses and hopefully I donít take you away from the rest of your moderating. Letís see how many words I wrote this time.
    Last edited by Alaric Darconville; 07-09-2020 at 09:29 AM. Reason: Removed COLOR/FONT tagging

  4. #4
    Flashaholic
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    Default Re: A few(many) headlight engineering questions. Also help upgrading two carsí lights

    It looks like Virgil did a great job answering your questions. I'm assuming you've already reached out to Daniel for a consult. If not, please do so.

    I just recently found out that he has the Toshiba 9011 bulbs for less than half of what I paid for Toyota packaged bulbs. I use them in my GMC Denali OEM projector low beams and will have them in the high beams in both my GMC & Chevy trucks.

    I'd imagine his 65w H7 bulbs would work great in your projector low beams. I'm able to use them in the high beams of my wife's Porsche Cayenne Turbo, and they are great.



    Sidebar:
    Speaking of "spirited drives," I'm eager to see this MR2 of yours. I have an '88 911 that we've driven out to SoCal twice, Texas Hill Country, the Smokies twice (incl Tail of the Dragon both times,) recently Colorado and planning on heading back out to NC this fall for another Rallye.

    pics for fun can be found here: https://www.instagram.com/patrickossenkop/

  5. #5

    Default Re: A few(many) headlight engineering questions. Also help upgrading two carsí lights

    Quote Originally Posted by Mr. Merk View Post
    It looks like Virgil did a great job answering your questions. I'm assuming you've already reached out to Daniel for a consult. If not, please do so.


    Yeah I was happy to get such a thorough response and have my questions taken seriously. I hope Iíll get enough of my questions answered here that I wonít have to send Stern pages of questions. Iíll be picking up a few things from him soon, so Iíll add it onto there.

    Quote Originally Posted by Mr. Merk View Post
    Sidebar:
    Quote Originally Posted by Mr. Merk View Post
    Speaking of "spirited drives," I'm eager to see this MR2 of yours. I have an '88 911 that we've driven out to SoCal twice, Texas Hill Country, the Smokies twice (incl Tail of the Dragon both times,) recently Colorado and planning on heading back out to NC this fall for another Rallye.
    I wish I could, but Iím still shopping for one. Recently expanded my search to the entire east coast, but I havenít found a later model in decent shape with a manual. All the cheap spyders are the floppy early models with the piston ring and pre-cat problems, and all the later spyders are either semi-auto (which Iím starting to consider converting to manual), or $15k. Perhaps once COVID is over, used prices will come down again.

    I do have pictures of my old miata at the tail of the dragon. That was my favorite road trip - all the way down the Blue Ridge Parkway from PA. https://imgur.com/gallery/gCa8oUP

  6. #6

    Default Re: A few(many) headlight engineering questions. Also help upgrading two carsí lights

    Iím disappointed that so much of the engineering behind headlamps is off limits to most people
    It's not unusual. That's how it works for pretty much every part of the car. The tires, the paint, the brakes, the engine and all of its parts, the emission control system...everything. Planes, too. And can openers, dishwashers, garage door openers, telephones...

    Iíll be aware of the complexity of modern cars, and see if I can find a wiring diagram to avoid breaking any functionality.
    A wiring diagram won't really tell you what you need to know.

    If you do install one, however, you will have to find an access point for + and -. You may have to run a cable in a sturdy raceway or jacket of some kind to the battery, or the starter, or the alternator.

    Based on this answer, Iím leaning towards something like the Opti-Lens. That way I can somewhat restore the Impreza lights and protect them for a year or two, and the use the coating as extra protection on the new MR2 headlight lenses
    It would not be wise to add random substances as "extra protection". They may very well not be compatible with the coating already on the new lenses, then you could really wind up with an expensive mess.

    Iím curious how projectors are more susceptible to UV damage. I would have thought that the glass/plastic aspheric lens would protect the inside of the projector by absorbing whatever UV made it though the cover lens.
    Projector reflectors are more susceptible to heat-induced deterioration because the reflector, being relatively small, is close to the bulb, and therefore gets/stays hotter.

    Don't get too caught up comparing theoretical efficiency advantages of various kinds of optics. Usually we don't get to make an all-other-factors-equal comparison (there are a few cases, like certain older BMWs and VWs, but it's not common).

    Some dual-filament reflector lamp systems can use the entire reflector surface. That is the case with the HB1 (9004), HB5 (9007), H13, H14, and some obscure Japan-only types. H4 (9003, HB2) and H19 cannot, because of the low beam filament shield.

    UN Regulations have permitted plastic headlamp lenses since late 1992, and virtually all vehicles have had plastic lenses for many years now. There is no "EUDM" headlamp for a Toyota, because there are no "EUDM" Toyotas. There are European-market or European-spec Toyotas, and most of them have plastic lenses. The beam patterns would potentially be different on the European-spec headlamp, and potentially but not necessarily better...or worse. In some cases European headlamps are a direct bolt-in swap for North American-spec units, and sometimes not.

    isnít testing the overly large filament 100/90W H4 bulb not the greatest illustration of overwattage bulbs? (...) Iíd be curious to see your measurements of the stated top performance bulbs such as the Osram 85/80W versions.
    The Osram 85/80w bulb was not in production for very long, was not a very practical bulb (very short life, tendency to blister the glass) and is no longer available, so not much point in spending money on testing a few dusty-box samples off the back of the shelf.

    Is there a story about why Osram ever built the H7 Rallye?
    Probably...!

    how much would the 10$ Wagner 9011s perform
    Inexpensive junk is still junk. See here.

    Hella 90mm projectors I was interested in: I figured rigidity might be a problem. Is there no aiming strategy that could avoid glare?
    You would have to aim them so far down that they would be completely useless.

    Would a more rigid mount, perhaps attaching to the body or subframe resolve this? I suppose that could mess with crash structures, but it canít be worse than tow hitches on unibody cars
    Talk about doing it the hard way! Steer your attention back to the vehicle's headlamps.

    Also, out of curiosity, what kind of beam profile does that projector have?
    What do you mean by "beam profile"?

    Iím curious what you think the problems with ALR/EVO88ís testing is.
    I'm not in a mood to spell it out chapter-and-verse; I think my previously posted general observations are probably enough.

    Then what can I trust?
    Unfortunately there is no Consumer Reports style resource specifically for the deep details of vehicle headlamps.

    often times it seems your and Alaricís suggestions are just based on hidden data and information, despite the explanation. Not that I have a solution to this problem of course.
    Well, yeah, you've kind of nailed it. The alternative to the way things are is "no information at all".

    What sources can I generally trust? At this point Iím down to IIHS test data
    The IIHS tests are really good, as long as you interpret them correctly.

    their insistence that crimped connectors were inferior to soldering and shrink wrap. I thought soldering was too fragile/rigid/inflexible for the vibrating car environment
    Again, theory/practice. We mostly do not live in a yes/no, black/white world. A good solder joint is better than a bad crimp and vice versa.

    How about an H7 projector from 2003 vs one from 2020? If there are any left
    There were many different H7 projectors made in 2003, and many different H7 projectors made in 2020.

    That beam distribution article you found contains a certain amount of technical theory, a certain amount of the writer's opinions, and a disappointing amount of squishy "based on customer feedback" stuff (which, it's made clear, is subjective preferences and asks...and given where the author is employed, we know the preferences and asks are not coming from knowledgeable people; they're coming from kids who treat their car's lights as toys).

    Iím curious how you made the judgements on what lamp would deliver better performance. Is this all just based on the pictures and bulbs used?
    It is usually not possible to make a better/worse comparison judgment by looking at pictures and noting what kind of bulb is used. In the particular case you're asking about, it's pretty close to a most-other-factors-equal comparison: same size, shape, and technology; same manufacturer using the same development and manufacturing processes, for the same automaker's internal standards and preferences. Optically speaking, H7 is inherently superior to HB4: it's a newer design with much better filament precision, a no-metal zone around the filament which reduces stray light and inherent glare, etc. And it produces about 40% more flux, plus greater luminance. Also, just as there are no "EUDM" Toyotas, there are no "USDM" ones, either.

    how do you know the H7 projector will perform better than even the optically limited H4?
    Much in the same reason why we know that a 2019 Toyota Camry will perform better in every way than a 1969 Toyota Corona.

    Would the suggestion change if they were both single filament bulbs?
    Too many variables to answer generically. Which single filament bulbs in how good of an example of what kind of optic?

    What about if the H7 was lowered to 1000 lumens to match the H4?
    The advantage would still go to the H7. Consider what happened when the 2000 Camry came with HB4/HB3 headlamps instead of the previous year's H4 units. The new lamps were fractionally taller than the old ones, but otherwise very similar size and shape, and the new lamp just beat the pants off the old lamp. And the '98-'00 Toyota RAV4 headlamp, HB4/HB3, beats the pants off the '94-'97 H4 unit of the same size and shape.

    My uneducated thought was that perhaps increase foreground isnít as harmful as itís said to be
    You're thinking along the right line. Excessive foreground light is one factor among many. It's usually not a do-or-die/make-or-break factor in whether an obstacle can be seen. That's on dry roads, mind you; let the road be wet and the reflected glare to oncoming and preceding drivers can be brutal.

    Letís see how many words I wrote this time.
    About 2700.
    Last edited by -Virgil-; 07-08-2020 at 08:28 PM.

  7. #7
    Moderator Alaric Darconville's Avatar
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    Default Re: A few(many) headlight engineering questions. Also help upgrading two carsí lights

    Vaan,

    I've removed the FONT and COLOR tagging from your posts; the reduction in the font size made a slight challenge to read, and the color stuff, since COLOR=#000000, didn't even do anything. You might wish to use a plain text editor like Notepad.exe or NotePad++, or if using Word make it a plain-text document.

    One thing I noticed was you are also looking at fog lamps; from a "completionist" perspective, it is nice where you have every switch and button possible and every feature you can, but front fog lamps have been all but obsolesced by modern headlighting systems.

    What you really want in terms of a fog lamp is a *rear* one; you're in greater danger of getting rear-ended in the fog or torrential rain by someone with front fog lamps (or no fog lamps at all) than you are of going off the road, or rear-ending someone else, because you didn't have front fog lamps. If the model year or generation MR2 you want was also sold in France or Belgium or Germany, or other UNECE signatories, those rear lamps probably have the rear fog lamp integrated into them, then you just need to wire them (or, better yet, just the one on the left side) up. (It's possible there's just a separate Toyota rear fog lamp assembly instead of it being integrated into the rear lamp assembly). A single rear fog lamp on the left side of the car disambiguates the signal; it is much less likely to look like a "stuck on" stop lamp, and being on the left side it's more visible to following drivers than when centered. (Note that the best practice wiring is more complicated than a single switch with full manual control, but that would make the rest of this post longer than I'm prepared to write. It involves telltales and latching relays and such.)

    As far as mounting other lamps where your front fog lamps would go, there's really not much in the way of practical distance lighting you can put so low on a car.
    Last edited by Alaric Darconville; 07-09-2020 at 12:12 PM.

  8. #8

    Default Re: A few(many) headlight engineering questions. Also help upgrading two carsí lights

    Alaric is right, and just to be clear, a rear fog lamp is not just a regular fog lamp mounted on the rear; it's a completely different thing. They're required by UN Regulations, which means they're present on all cars sold throughout Europe and the numerous other countries that apply the UN Regs. Whether to limit your search to countries with right-side traffic or include the UK depends on whether the automaker installed only a single rear fog on the driver's side, or provided a pair of them. The "stuck-on brake lights look" is an issue if the rear fog is located close to the brake light on each side and is of similar size, but that's often not the case, and a pair of rear fogs can make it easier for following drivers to gauge the distance from their car to yours (another example of how these things are complicated, with a variety of factors "competing" with each other).

    Also be careful if you find that your particular model, as sold in Europe/etc, had the rear fog built into the main taillight cluster and the car, as sold in the USA, has the side marker light and/or side reflector built into the main taillight cluster. If that's the case, installing the EU cluster would mean you'd have to add separate side marker lights and reflectors. If the EU version has the rear fog built in somewhere else, like an inner taillight on the deck lid, that avoids that problem but can create other problems (license plate mounting). If the EU version has the rear fog in the bumper, that might or might not make issues of its own (different bumper cover, etc).
    Last edited by -Virgil-; 07-09-2020 at 12:13 PM.

  9. #9
    Flashaholic* turbodog's Avatar
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    Default Re: A few(many) headlight engineering questions. Also help upgrading two carsí lights

    Agreed... that's the longest post I remember reading in my ~15 years here. And to be honest, I barely skimmed pieces of it and Virgil's first reply.

    That said, I will add this. Maybe it will help you, maybe not. It's not exactly easy, and I would first check if your existing system is damaged.

    If your lights are yellow and vary when the engine revs you could put a relay and DC to DC voltage booster & regulator. This would provide consistent voltage which will eliminate the up/down brightness. It will also (assuming you put a variable one) allow you to fine tune the bulb voltage which will let you get some more output (at the expense of bulb life). I strongly caution you about going 'too far' and blinding other drivers. I would let total consumed wattage be my benchmark to which I adhere.

    I'm pretty sure my honda truck uses something similar... they are feeding the headlights with a regulated voltage, not just straight off the battery.
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    Flashaholic* turbodog's Avatar
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    Default Re: A few(many) headlight engineering questions. Also help upgrading two carsí lights

    Did some googling. Honda uses a dual mode charge setting. Maybe your car does also and it's damaged, which is depressing your battery charge level/voltage.

    https://opensiuc.lib.siu.edu/cgi/vie...text=auto_pres
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  11. #11
    Flashaholic* turbodog's Avatar
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    Default Re: A few(many) headlight engineering questions. Also help upgrading two carsí lights

    Keep in mind your eyes response to light is logarithmic. It takes a LOT more light to be perceived as significant.

    This post gives some good tech breakdown of lumens and voltage drop. But I'm quite interested when he talks about foreground vs background illumination.

    Foreground = makes you feel good
    Background = illuminates stuff you will actually hit

    It's a good LONG read. Sure you will love it.

    https://www.thetruthaboutcars.com/20...-voltage-drop/


    Edit: apparently I stumbled across an article by someone that's a legit headlight expert. Might want to pin to the top somehow.

    "Daniel Stern has been a freelance vehicle lighting consultant for decades. Heís on several of the worldís technical standards development boards for vehicle lighting, and is Chief Editor of DrivingVisionNews, the global vehicle lighting and driver assistance industryís journal of record"
    Last edited by turbodog; 07-09-2020 at 12:09 PM.
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  12. #12
    Moderator Alaric Darconville's Avatar
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    Default Re: A few(many) headlight engineering questions. Also help upgrading two carsí lights

    Quote Originally Posted by turbodog View Post
    Edit: apparently I stumbled across an article by someone that's a legit headlight expert. Might want to pin to the top somehow.
    Daniel Stern's work has been referenced in the Automotive forum so often, they're practically a sticky already. If this is the first time you've seen his work, you might not be in this forum that much

    I stumble across posts by a legit headlamp expert all the time in the form of Virgil's posts. I'm used to it by now.

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