Q: I was wondering if anyone know if and how one can uprate the coupe series 1 headlight power / beam? I was doing a navigation rally recently and realised that they were pretty poor. I thought that rather than getting some spots it might be easier to up rate the bulb. Any thoughts??

A: The original headlights of the S1 Fulvia have what I call "duplo" bulbs. These are the old fashioned bulbs that had been used for decades before the arrival of halogen bulb. The first halogen bulbs were made around 1960 for use in landing lights of aircraft. Cars started to use them around 1970. The S2 Fulvia has halogen lights. The bulbs are so called H1 bulbs with only one filament. A light unit with H1 bulbs is either for low beam or for high beam. The H1 bulb uses 55 watts of power. This translates into 4,5 Amps in a 12 volt system.

The duplo bulb has two filaments. If the reflector and lenses of the light unit are properly designed, one can use the same light unit for high beam and low beam by switching beteen the two filaments. The filament for the high beam uses 45 watt or (3,5 amps from 12 volt). The filament for the low beam uses 40 watt (3,3 amps from 12 volt).

Some years after the H1 bulb appeared, the H4 halogen bulb was introduced. The H4 bulb has two filaments. 60 watts (5 Amp) for the main beam filament and 55 watts (4,5 amps) for the low beam filament. Once again it was possible to make one light unit for low beam and main beam.

There is also a halogen version of the duplo bulb. The base of the duplo bulb is different from the base of an H4 bulb. Also the filaments are not in the same place. Some manufactures make H4 bulbs with a duplo base and offer it as a duplo replacement. This is no good as the filaments are in the wrong places. The Philips bulbs are excellent. The filaments are exactly in the right places and the power consumption is 45/40 Watt exactly as the duplo bulbs themselves.

Before I go on, some simplified basics about filaments, light and life time. If one raises the voltage just a bit, the light output goes up dramatically. The life time however goes down even more dramatically. For every 20% increase of voltage light output doubles. However, the life expectancy of a bulb is halved when the voltage goes up 5%. Vice versa, if the voltage drops 20% the light output is reduced by 50% but the life expectancy is doubled for every 5% of reduction in voltage. It is some years ago, that I was involved in the light business. I am not sure, the precentages I gave are exact. The principle is certainly correct. It means every light bulb is optimised for its nominal voltage weighing light output versus life time. I sometimes hear people say that light bulb manufacturers make bulbs that fail on purpose to sell more bulbs. This is a fairy tale. The only bulb that lasts for ever is a bulb that is switched off. What is true is that the compromise between light output and life time has been pushed towards more light at the same life time such as the Philps Vision Plus bulbs. Philips also offers long life halogen bulbs. Here the compromise is in the other direction.

The cause of failure of a light bulb is usually a broken filament because the metal has vaporized as a result of the very high temperature. The advantage of halogen is, that the gas in the bulb causes the vaporized metals to deposit themselves back onto the filament. They can thus be run at much higher temperatures which results in a small bulb giving a lot of light.

It is important that every light bulb is operated at its correct voltage. The bulbs for our Fulvia's are labelled 12V bulbs. This is more a name than a specification of the voltage. Our cars have a 12 volt battery but if the engine is running the dynamo or alternator generates a higher voltage, usually 14,0V. In reality the bulbs are optimised for 13,2V. This means we have to aim for a loss of 0,8V in the wiring and contacts.

If you want to optimize your lights, you can play a bit with the voltage. A bit less than 13, 2V (let's say 13,0V or 12,8V) to increase the life time at the expense of light output, if you normally drive with your lights on during daytime. Or 13,5V if you want more light during night rallies at the expense of a much shorter life time. You can however make it a part of the preparation for a rally to change the bulbs. The voltages are of course measured at the bulb. Remember that you can loose voltage over the ground wire and ground connection as well as the life wire, its connectors, the switches and fuses.

It is a very good idea to accurately measure the voltage from the voltage regulator. The ideal voltage is 14,00 volt. If it is lower the battery will not be fully charged and it becomes difficult to get 13,2V at the headlights. If it is higher the dynamo or alternator has to work harder and becomes hotter. The enemy of a dynamo or alternator is temperature. Also the risk of a boiling battery increases. At 14,5V you are definetely in the danger zone. You don't want the battery to boil and spill acid on the fuel lines running below it. If you have the capability to adjust the voltage of the regulator, you can adjust it to 14,1V to have the best possible light ouput if you are doing night rallies. If you have a series 1 Fulvia with a dynamo, run the engine at 3000 rpm when measuring the voltage. The alternator of a series 2 delivers full power at a lower rpm than the dynamo. When you are at it, also check the thick red and black wires going from dynamo to voltage regulator and the thick red one going to the fuse box. I often put second ones in parallel.

If the reflectors and lenses of the light units are ok, consider to keep them and just replace the duplo bulbs with their halogen equivalents. Also make sure the voltages at the bulbs are ok. On the S2 the voltages are usually ok as the currents do not go through the switches but are switched on and off by relays. On the S1 it looks like there is also a relay for the headlights. Well, there is but only the current for the low beams comes directly from the +12V, unfortunately through a fuse, and is switched by the relay only. After the relay the left and right low beam lights each have their own fuse. The current thus has to pass through a fuse twice. On most cars this is not a problem, but if the contacts are not in 100% condition you may loose too much voltage there.

The circuit for main beams on the S1 is a disaster. The current for the 4 (FOUR) main beams goes through the switch on the dashboard AND through the relay. I would fire an electrical engineer who designs a circuit like that. I hardly ever measure more than 11 volts at the filaments for the main beams. At 11 volts they produce hardly more light than a candle. On S1 cars it is absolutely necessary to insert a relay for the main beams. On coupes, you can put it in the tray under the glove compartment where the fuses are. In berlina's it can be put on the panel under the bonnet where the relay and the voltage regulator is.

The original outer light units have small hoods in front of the light bulbs. This is to prevent light being radiated straight forward which is not allowed in the low beam position. This is true for the S1 units with the duplo bulbs as well as for the S2 units with H1 bulbs. The S2 low beam unit is for low beam only. The S1 low beam unit is also for main beam. The main beam from this unit suffers from the hood in front of the bulb and is relatively wide and short. On both the S1 and S2 the inner head lights are optimised for a longer and thus narrower beam. The S1 inner head lights do have duplo bulbs. This is not because the units were originally low beam / high beam units which were turned into high beam only units by simply not connecting the filament for the low beam. The hood is not there and the reflector and lens are optimised for high beam. The duplo bulbs are used simply because there were no high power bulbs with only one filament available at the time. There is no way these units can be used for legal low beam.

One of my S1 coupes still has the original Carello head lights for the duplo bulbs. I have inserted a relay and replaced the duplo bulbs with their halogen equivalents of 45/40 watts. We have done night rallies with it without problems.

If the head lights of an S1 Fulvia have to be replaced, I use H1 main beam units for the inner ones and H4 units with city light for the outer ones. Normally I have Cibie units in stock. They are of excellent quality, have curved lenses and produce an effective pattern to better spot pot holes and movements on the side of the roads. They also light the overhead signs well. The same Cibie units can be used to replace the H1 units of the S2 Fulvia. The inner ones are a direct replacement. On the outer ones I only connect the filament for the low beam of the H4 Cibie unit on S2 cars. On S1 cars one uses both the low beam and the high beam.

The low beam from an H4 unit is better than from an H1 unit. On the H1 units the light that is radiated down from the bulb is wasted and also the hood takes away light. On H4 bulbs there is a small mirror under the low beam filament and the top of the bulb is black which is a smaller obstacle to the light beam than the hood in front of the bulb.

Light units are precision optical systems. The filament has to be in the focus position to produce the most effective pattern. Using 100 Watt bulbs is often counterproductive. The filaments are much bigger and most of the filament is not in the focal point. They may throw a lot of light forward but the efficiency of the pattern is lost. Also the current that 100 Watt bulbs draw is twice as high compared to 55 Watt bulbs. Voltage drops in the wiring are thus also twice as high. I have seen cases were 100 Watt bulbs actually produced less light than 55 Watt bulbs because the voltage was more than 20% lower as a result of the very high currents.

100 watt bulbs are also too much for the dynamo / alternator. At best you will only suffer from a flat battery, but chances are that you will ruin the voltage regulator and dynamo / alternator. I have seen people putting 90 Amp dynamo's in. This is no good. The wiring was calculated for the 30 Amp (or there abouts) units. Sooner or later the 90 Amp unit is going to deliver 90 Amps and the wiring will burn. And remember the electrical power does come from the fuel tank in the end. I am sure the engine can handle an extra kilowatt, but the V belt cannot. The single V belt as used on the Fulvia's is good for 45 Amps max. If you like your car to be reliable, best limit it to 40 Amps.

Let's make some simple calcuations. Just for fun. I am talking now like my old math teacher of a hundred years ago, but here is the first.

Low beams have to angle down by law. This is called inclination and given as a percentage. If the inclination is 2% it means, that at a distance of 1 meter the top of the beam has dropped 2 cm or 20 cm at 10 meters. Since the head lights of a Fulvia coupe are positioned very low, I put the inclination at the legal minium of 1%. This means that if the headlights are 50cm off the ground the beams intersect with the ground 50 meters in front of the car. This is not much. Light intensity decrease with the square of the distance. Since the distance of the low beams is low, there is no need for high intensity bulbs for the low beams. The standard or long life versions of either H4 or H1 bulbs are the obvious choice. Certainly if one drives with the headlights on during the day.

The second calculation is revealing. Here it is. The Data Tecnici gives a braking distance of just under 60 meters at a speed of 100km/h for some of the models. Braking distance is proportional to the square of the speed V. Let's round the braking distance of a Fulvia off to d_brake =  V²/160. Let's now calculate our maximum speed for safe driving with low beams that shine 50 meters in front of the car. We allow 2 seconds reaction time. The distance in meters covered in two seconds is d_reaction = V/1,8 with V in km/h.
The total stopping distance is d_total = d_brake + d_reaction = V²/160 + V/1,8. At a speed of 55 km/h the total stopping distance is 50 meters. Thus the safe maximum speed of any car with low beams mounted at a height of 50 cm from the ground is 55km/h when driving with low beams and the inclination of the low beams set at the legal limit.

The third calculations is the length of the main beam we need when driving 150km/h. We use the same formula d_total = V²/160 + V/1,8. When substituting 150 for V we get 225 meters. We need main beams with a beam of at least 225 meters. A good H1 unit should be able to do that easily.

Huib, huib@viva-lancia.com