Thanks for the story Nautilus. Lots of good points. I do want to debate you on the fact that these parts are useless for mpg. Their impact may be almost negligible on the dyno but over 100k of gas/brake gas/brake, the cumulative affect of: simple weight reduction, rotating inertia reduction, reduced pumping load would add up. Drag racers have a saying "Start saving ounces and you will save pounds."
As far as underdriving the alternator, avoid it: The shaft load is proportional to the electrical load. As Nautilus found, spinning them slower (at same load) will cause the bearings or electrical parts to die. Thanks for the knowledge.
Quote:
Originally Posted by Nautilus
There was a slight (almost too slight to feel) increase in engine responsiveness and nothing more. But after 1 year and half, accessories on the serpentine belt began to make grinding noises at idle rpm and alternator voltage went down. There was no noise or vibration above 1500 rpm.
Removed the serpentine belt and checked: alternator slight grinding (bearings worn away), belt tensioner also slight grinding. Replaced both. Also went back to OEM clutched pulley.
In racing, where the engine runs for short time and mostly above 6000 rpm, the slightly better engine responsiveness may help.
In city driving, it will, sooner or later, wear down accessories (alternator, A/C compressor, power steering pump) because solid metal pulley does not allow any compensation for any fault - the smallest wobble in a bearing is amplified by belt tension until it gnaws away at the bearing or the tensioner. Or both.
|