1. turbofiat124

    turbofiat124 Premium Member Forum Donor

    I've never seen a Trabant with this sort of modification done to it. Either someone has tried it and there is a reason behind it, or nobody has thought of it which I find hard to believe.

    Years ago I threw a V-belt on my Fiat 124 Spider. The weirdest thing. The belt had stretched (probably from removing it more than a few times), flipped itself inside out yet was still wrapped around all three pulleys! But it was stretched to the point there was too much slack to tighten it. Luckily I was not far from an autoparts store. Ever since then I keep a spare V-belt with me in most of the old cars.

    The first thing I noticed was a sudden increase in power. Then I noticed the battery indicator light was on and the temperature gauge was starting to rise. My guess is because due to the lack of drag on the alternator and water pump explained the increase in power.

    This always made me wonder if it were possible to install an electro-magnetic clutch either on the crankshaft pulley or water pump or alternator that would disengage whenever the turbo kicked in to reduce engine drag. Since the turbo is only spinning in a few second bursts, I could possibly get away without over heating or discharging the battery. I could even add an over ride switch if I wanted to.

    Well I never got around to it on the Fiat but about a year ago, about the same thing happened again but with my Trabant. I did not get the "tit" on the fan housing aligned with the hole in the engine cradle and eventually I threw a belt. If you ever throw a V-belt on a Trabant, you will definitely know it. The engine RPMs will dramatically increase. Kind of like if the throttle return spring breaks. Which has also happened to me.

    I don't know how much drag the mechanical fan or alternator creates on a Trabant so I don't know if this would be a worthwhile experiment. Mounting the fan could be easy with some custom brackets but the question is the mechanical fan spins in proportion to the engine speed. Anyone ever notice that when pulling away from a redlight after sitting for about a minute, there is this sudden burst of heat from the heater?

    Unless some sort of speed controller was used to regulate the fan, it would spin the same no matter what the engine was turning. I don't know what effect this would have.

    The other concern is engine temperature. It may run either too hot or too cold.

    The engine temperature would need to be monitored with the mechanical fan then compared using the electric fan to make sure the temperature stays within range.

    If the electric fan could not adequately cool the engine at full throttle, I guess a shroud and duct could be installed to channel air through the front grill.

  2. trondd

    trondd Loyal Comrade

    You're always thinking of something...

    No free lunch. The energy to turn the electric fan has to come from somewhere. The motor via the alternator. A mechanical fan takes the rotation of the motor and turn it into....rotation of the fan.

    An electric fan takes the rotation of the motor, spins the alternator to generate electricity, which gets turned into the rotation of the fan. You lose some any time you convert energy from one form to another.

    On the other hand, a fan spinning based on engine speed isn't necessarily operating most efficiently. Engine speed does not equal engine load. A mechanical fan might not provide enough cooling during low rpm, high load conditions and may be over cooling during high rpm, low load conditions. An electric fan, able to operate based on temperature, and possibly shut off completely when not needed, may be a net improvement in efficiency.
  3. turbofiat124

    turbofiat124 Premium Member Forum Donor

    You know after I posted that, I got to thinking that the alternator does create quite a bit of load on the engine. Those fans pull about 4 amps so the demand in electrical power from the alternator would probably equal out.

    I installed a 60 amp GM alternator in place of the 30 amp generator on mine and it took care of the issue I had with my upgraded lights but caused the engine speed to drop about 200 RPMs at idle. I ended up having to install a 6 to 12 volt step up converter between the headlight switch and hi/low toggle switch. this dropped the amperage draw from a total of 28 amps down to 4 amps and seemed to solve that issue.
  4. Andrewwoey

    Andrewwoey Loyal Comrade

    I'm sure there is some equation that can work out the power draw of the belt fan. Otherwise its a case of, try it and see. You would possibly need a thermo sensor on the cylinder furthest from the fan. This could switch on the fan at a set temperature or different speeds at different temperatures.

  5. Austinpowers

    Austinpowers Loyal Comrade

    A belt driven fan normally uses 2-3 hp, which on something that has 26hp to start with is quite a bit.
    I have thought about trying this ever since I bought my Trabi. I have a spare fan shroud that I could adapt.
    Maybe it’s time to have a look on eBay for a cheap fan to experiment with.
  6. 'bant

    'bant Loyal Comrade

    This has been done with 2cvs, usually 4wd ones where you don't want the fan spraying water over the engine while going through deep water.

    If I understand correctly then you fit a temperature sensor on your cylinders/heads somewhere and work out what is a safe operating temperature and use that to control the fan. As it was a while ago I haven't kept up with developments and don't know if people have developed the idea further with automatic fan control systems.

    I would assume that any automated fan control would default to ON if the control system failed.
  7. 'bant

    'bant Loyal Comrade

    My Dyane has a "blower" system fitted as standard where the air cleaner inlet is connected to the cooling fan shroud. That forces air into the engine and IIRC is good for a couple of hp at higher revs. That is what I thought you were going to suggest when I read the thread title ;) You can buy aftermarket kits for 2cvs that do the same thing.
  8. 'bant

    'bant Loyal Comrade

    Re your alternator 60A x 12v = 720W which is about 1 hp.

    Fit a 30 amp generator and you gain 1/2 hp straight away. :D

    Re-fit the old Trabant generator and you gain even more...
  9. 'bant

    'bant Loyal Comrade

    The same idea is used by people who try to improve the fuel consumption of older water cooled cars. They use electric motors to drive the water pump so that the water flow through the engine is just enough to keep it cool. This saves energy, compared to a belt driven water pump and it must be a big enough saving to make it worthwhile.

    The main problem with such alterations you have to carry a spare electric motor round with you instead of just a spare fanbelt.
  10. mbeamish

    mbeamish Loyal Comrade

    i don't think fitting a different generator will change anything , yes a 60 amp will draw 1hp when charging at max but when the battery is fully charged it will 'idle' and only draw enough to run the ignition
  11. Ian

    Ian Loyal Comrade

    Hi,...When you said about stepping-up with a converter,...presumably your Trabi is a 6 volt model?

    I have a rally Trabant, which I am just completing a total rebuild of and have upgraded to a Lucas 12 v alternator, on my 12v system, as I have 6 x 60watt headlamps on the front.
    I wander if there is anything similar that I can do/fit, to help reduce the drop in revs of the engine at night, when at idle,...other than adjusting the Mikuni Carburettors' idel, to compensate?

    Any suggestions??....

    Much obliged.


  12. 'bant

    'bant Loyal Comrade

    I have a seasonal version of this problem with my Dyane. When running in winter with a much higher load on the alternator I just raise the idle a smidge. I only have to change the idle twice a year so that solution works for me. However, the choke on the Solex carb in Dyane pulls on a cam to raise the idle speed when the engine is cold. Maybe you could do something like that on the Mikuni? Run a separate cable to a cam that allows you to adjust the effective position of the throttle stop on the carb from the driver's seat.
  13. 'bant

    'bant Loyal Comrade

    It was meant as a bit of a joke but then again, try adding up the extra power draw of a few "normal" accessories that you might fit to a Trabant. ICE, uprated headlamp bulbs, driving lights, fan in the heating system/standheizung fan... The difference as well is that an alternator produces much more power at idle than the old style dynamos originally fitted to a Trabant. Thus an alternator will need more power from the engine to drive it at idle than a dynamo. Which probably explains why Turbofiat124 has had to raise the idle speed - higher power from accessories + the change from a dynamo to an alternator.

    I am happy to be corrected if I am talking tosh :)
  14. turbofiat124

    turbofiat124 Premium Member Forum Donor

    The alternator I am using is a standard 60 amp GM AC/Delco 10SI alternator but has an internal 6 volt voltage regulator.

    I upgraded to 6 volt 50/55 watt H4s and 6 volt H3 bulbs for my auxiliary lights which turn on whenever the high/main beams are on. I had to buy not only the bulbs but also the headlamp buckets from the UK! And the auxiliary lights I got from Halfords when I was in the UK back in the late 90s.

    With the 220 watt generator, the battery indicator would sometimes glow when taking off from a dead stop in 1st gear. So I knew my lights were pulling more than the charging system could handle.

    Like in your case, the alternator would detect this current draw and reduce the idle speed by around 200 RPMs.

    Back in the winter, I swapped out all of the H4s for LEDs. I mounted one of those 6 to 12 volt converters where the original external voltage regulator was located. The post on the headlight switch which runs to the dimmer switch, I placed this converter between it. So the 6V input wire from the step up converter connects to the "headlight" pin on the headlight switch. Then the 12V output wire from the converter goes to the dimmer switch. That way I didn't have to change any other bulbs.

    I didn't measure the initial current draw but I'm assuming it was around 28 amps (just using a amp/current calculator) but I did measure the current draw afterwards and the system is pulling 4 amps. This seemed to take care of the idle speed drop with the lights on.

    Here's a thread with some photos:

  15. 'bant

    'bant Loyal Comrade

    IIRC to set the idle speed on a stock Trabant you turn on the headlights, then adjust the idle until the charging light just starts glowing.

Share This Page