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MG MGB Technical - Brighter Headligh Bulbs

I was looking in Halfords at the weekend for some brighter headlight bulbs. I noticed that some of the lights claim to be 20%, 30% & 50% brighter, but are still the same Wattage (55W). I assume that as the light level is logarithmic, then even 50% brighter is not that much?
Anyway, in amongst the £16 bright blue boy-racer lights there is some ‘off-road’ (90W & 100W) obviously outside on the Construction & Use Regulations, for £6, much more like my price range and obviously a good deal brighter.
The exam question is; does anyone have experience of using these in a F/TF, my concern is that the increased current consumption may overheat the wire or switch contacts. Rover being optimal on most things, I again assume that the wire is only just good enough for the standard 55W lamps. Prolonged experience is the only real answer to this…
I live out in the country and drive for many miles on ‘B’ roads, with no street lighting, bloody pheasants all over the place, cats, foxes and stupid locals with no lights on their bikes riding home from the pub! I NEED some bright lights!

I put the 100W bulbs in my Cibie lenses but used the Victoria British high power relay system. They draw considerably more current so I felt the wiring upgrade was necessary. The Cibie headlights have a very sharp horizontal cutoff and a gentle rise to the right(here in the USA) for better viewing on the side of the road. I found that the light near the car, down and to the sides is very good for driving on those slower dark roads. It shouldn't bother oncoming drivers too much unless you crest a hill or hit a good bump.
CD Dewey

Yesterday I purchased 2 Round Diamond headlight Capsules and to Sylvania Silver Stare Halogen lights. I could only test them with a battery beacuse I am re-wiring my car right now but they seem a lot brighter than the standard MGB light. I also purchased 2 new sockets. Everything ran me about $100.
bsf Fowler

Hi all.

It is very easy to make a light bulb brighter for the same input power IF you accept that the life of the bulb will be significantly lower than a 'standard' one.

A hefty wiring upgrade would not only avoid any risk of the wiring overheating, it would also reduce the wiring voltage drops and hence get more power to the bulbs.
An upgrade should include relays to take the high current load off the light switch and dip switch.
Don't forget the earth return wires will also be carrying a higher current.

If I was doing this modification I would put a pair of relays close to the front of the car and feed these from a thick wire from the 'brown' circuit.
The original feeds to the lights would be used to operate the relays. The subject of fusing lighting circuits was recently discussed in another thread.

The headlamps assemblies would get significantly hotter, there is some risk that the connectors would deteriorate.

Ball park current figures are 1A for each 12W of power.

Don't forget that dipped beam AND main beam can be on simultaneously if the flasher is operated.

An alternator upgrade would be well worth considering.


It isn't the bulbs that make for better lights but the design of the lens and the entire headlamp. I've seen (and bought) a few headlights that were quite poorly designed and when I switched to a Hella E code headlight the difference was quite amazing and that was using the same wattage bulb.
Michael MaGee

To summarise: better lights are a combination of lens quality/design with the 'temperature', wattage and design (xenon versus regular halogen etc.) bulbs you have and whether those bulbs are able to operate at their rated voltage thanks to adequate and well-maintained wiring. 60W bulbs of enhanced halogen bulbs in theory draw the same current, hence produce a similar amount of heat as regular 60W halogens. IMHO, 100W bulbs really aren't necessary and in many jurisdictions are in fact illegal.

I'm running Narva +50% (xenon) 60/55W through Cibie 7" lenses, powered directly from the alternator via a heavy duty dual-fused headlamp relay. Very nice light :)
Curtis Walker

Rosie - the Hella bowls are available over here for about £30 each and provide a very noticeable improvement as michael suggested earlier.

The original wiring will just about survive the extra current for the 100w bulbs if it is in good order but the stalk indicator may well melt and cease to function. The improvement with 100w is less noticeable than from the Hella change.

If your headlamp looms have been renewed with the Club product - they would definitely melt if you use 100w bulbs.

Hope that helps


I would expect the Cibie lights to produce comparable results.

I got my lights from Daniel Stern in the US..he's very helpful, prompt and knowledgable, and his website is a pretty useful resource for getting' edumacated. Unfortunately his FAQ is down at the moment.

Basically (feel free to add more here, guys) automotive light levels may be objectively demonstrated on an 'isocandela' diagram, similar to the one here:

On the basis of that, I went with the Cibies over the Hellas and have been very pleased.

[not affiliated to DS Lighting in any way, just a happy customer]
Curtis Walker

Ooops...forgot the link:
Curtis Walker

I think this one was meant for the MGF board.....
Steve Postins

Steve's right, Rosie has an MGF...
Mike Howlett

Thanks for the input all! My original post was indeed intended for my TF (2004), but I also have a ’72 BGT. I do need brighter lights on both, although the B rarely goes out in winter. The TF rarely goes out when it is wet, and I use a Fiesta for general running-a-round. The Fiesta lights are great and they are only 55W so I guess it’s all down to both the reflectors and the status of the wiring etc as advised. I regularly keep a watching eye on both the B and modern TF board.

This thread was discussed between 24/01/2006 and 26/01/2006

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.