Quote: Originally Posted by none
Wrong.
The alternator will be harder to turn when it is under more load (cranking out more amps.) The difference should be negligible, but a really crappy car with a high draw system (P4 running through inverter with raid and crt monitor, for example) might see a hit.
That is correct (mostly). Current is drawn NOT CREATED! That is the first thing you must understand in electronics. The car does NOT create full power all the time. If you have a 100 amp altenator, that means that it is CAPABLE of creating 100 amp without doing damage to itself. An altenator creates electricity by intersecting a magnetic field with a wire. The current is then created in the wire. The problem with that is that any wire carrying current, creates it's own magnetic field. Right Hand Rule will show that these two magnetic fields (the one used to create the current, and the one created BY the current) oppose one another, thus making a "load". The more current that is drawn, the larger the magnetic field that is created by the current, the harder it is to intersect the wire with the original field, thus further loading.
Where NONE is slightly incorrect, is that even a small system will put a heavy load on the altenator. Lets say that you're using a 150 Watt system (DC-DC, DC-AC, doesn't really matter, it's the wattage we're concerned with) to create 150W the altenator must produce 12.5 Amps of current (in a perfect world with no losses). Considering that most cars come with around a 100 Amp altenator (probably smaller on that 1.6L engine), that is 12.5% of the available current capacity. I vaguely remember something from fields that the force is the square of the increase, so if the car before computer were using say 50 Amps of power, increasing the current draw by an additional 1/4 would increase the load 56%, thus affecting gas milage, and performance.
But alas, your real problem is a 1.6L engine.