Xenon HID retrofits: an optical engineer's view

lucky b'stard! i keep meaning to get the kit from my MR2 Turbo converted to the BMW, needs diffrent bulbs when i have the cash i'll get them swapped with my mate and fitted! makes such a difference! miss having them!

So basically what you're saying is run 100W bulbs and don't bother pissing about unless you want to lay down serious cash?

Unfortunately I'm not the lucky bastard at all who gets the benefit. I got the E36, a '99 323i Sport auto touring, as a replacement for my old e34 touring, hoping to save some cash on fuel. I made the big mistake of letting the SO have a go as she'd never driven an auto and *hated* the e34. Needless to say, I haven't seen it since. Apparently it's a "girlie car in a girlie colour" (M3 Techno Violet)! If I need 4 wheels now when I'm not using the bike or trike, I'm relgated to her VW Caravelle LWB TDi! (but which seems to now have a 'tuning module' suddenly appear in the ECU wiring loom! Can't think how that got there......

JB

Unfortubnately no. 100W lamps will kill the reflector coating in very short order. The easiest way to improve the e32/e34/e36 low beam ellipsoidals is to use Osram Silverstar lamps. Same wattage although less lamp life, but lots more luverly lumens. Not cheap, but well worth the outlay. The HID conversion was for me at least, an interesting (and fairly cheap) project. I got the £270 ballasts as 'evaluation samples' from the manufacturer and the Philips D2S lamps from Ebay, for £25 a pair brand new. The biggest pain was reworking the lampholders/mountings and the the new s/s masks.

JB

That's a 170bhp straight chip jobbie, is it?

Don't I wish. This is the ACV 5cyl 102bhp TDi lump with analogue injector pump control from the ECU. You're thinking of the newer common rail engine. still managed to get +25% on power and +30% on torque though, and even got as good as or better than standard economy. Hope you are keeping well Pete.

JB

Is it? Oh. Didn't know they did one with 102bhp - thought the minimum was

Not sure about commonrail - the 140bhp A6 engine wasn't commonrail, and I'm sure that's a straight chip upgrade to 170bhp. I did spot somewhere that VW use a 170bhp 5-pot 2.5TDI in the Touran - wonder if that's a commonrail version, or basically the same engine as the A6?

Cool - what sort of economy does one get from an old bus like that?

Cheers - well things are marginally better than completely s**te (I can see things slowly improving in a bit), but I'm not one to moan :-)

Same as the A6 115bhp lump but a different tune I suppose.

I think the lump in the touran is half of the loony V10 toureg engine. Although I could be talking s**te. I'm only now starting to learn these diesels

I get about 450-480 miles per £60 fill up. I do *not* hang about.

State normal I see then?

JB

Yup.

Thanks for the heads up on non Phillips D2S lamps. All the half decent product adverts say if you want more light use 5000K or 6000K, if you want a violet/blue appearance [1] and not a lot of light get 8000K+. They only claim about 3x output for the 5000K lamps.

-- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets!

Not true. I've had 100's in my E34 for nearly 2 years. Reflectors are still fine. Mike.

They may look fine, but if you do a side by side comparison with new ones you'd see the difference immediately. The extra infra red from the 100W lamps often causes the steel cutoff mask to distort like a piece of tinfoil too, causing wierd beam patterns. I think you may have been lucky though. Which headlamp assemblies have you got? ZVS or Bosch? This may make a difference.

JB

Even the old fashioned Hellas on my Golf? Seem to be chrome plated steel reflectors (MK2 Golf, round lamps)

You'll be ok with a chrome plating and high wattage lamps, but chrome hasn't been used for years. The plating process uses some nasty chemicals and the waste is classed as toxic. Modern reflectors, even steel ones use vacuum deposited aluminium reflector coating. This is quite soft, and susceptible to 'heat blooming' (oxidation). Aluminium is a much better reflector material optically than chrome too.

JB

I think I would have noticed any significant deterioration in light output or beam pattern. I'm still happy with the lighting, which is more than I can say was the case with the original 55w bulbs.

AFAIK they are Bosch, but I'll check today and let you know. Other owners might be interested. Mike.

It would be a gradual process over many 10s of burning hours. I doubt if you'd notice unless you compared sis by side with a new one.

Agreed. with standard H1 lamps the output is truly crap. superb beam shape but you can see sweet f*ck all. This is more a function of the ellipsoidal reflector and aspheric lens system found in these so-called 'projector' optics.

The Bosch units seem to last a bit better with higher wattage lamps than the ZVS.

JB

How modern's modern? 15 year old car...

If they are Bosch/hella/Cibie optics they will almost certainly be vac-aluminised steel. Simple symmetric reflectors are still cheaper to produce in steel. All of the newer fancy 'freeform' multi lamp, multi function optics are vac-aluminised polymer. I still say you'd be better off with Osram Silverstars, auxilliary relays and good thick wiring back to the battery. Volt drop in standard wiring harnesses and connectors can be *really* bad news, especially at the 8.33A needed per 100W lamp.

JB

It's a known fact that VW golf lamp wiring is naff. 100W bulbs are cheaper than silverstars / vision plus though :).