Warthog Posted August 11, 2006 Share Posted August 11, 2006 Is there any electrickery theory, referance to required "Pulley" diameters and alternator types (amperage rating) and RPM I have two 120 amp alternators on a D90 300TDI But have been running one with a smaller pulley. This would mean that its RPM would be higher than the other. I am thinking that the Alternator with the small pulley will not last as long? Are there Max and Min RPM rating for Alternators? Reason, for the small pulley is that the Aircon drive belt wont fit over the the standard size pulley, when the 2nd alt is mounted in the aircon spot (Using the aircon belt, as drive belt for it) Will eventually get a longer belt, but curious... Cheers Quote Link to comment Share on other sites More sharing options...
western Posted August 11, 2006 Share Posted August 11, 2006 (edited) There's 2 polyvee belt pulleys for Defender 300Tdi alts. diameters & part numbers ------ a 49mm From VIN TA969103------Pt No STC3202 & a 61mm To VIN MA969102----------Pt No STC1796 Reckon you have one of each, hth there's also a STC3691 on Disco 300Tdi's but doesn't tell me diameter or VIN details, the 2 above for Defender are also used on RRC with 300Tdi engine fitted. Edited August 11, 2006 by western Quote Link to comment Share on other sites More sharing options...
simonb Posted August 12, 2006 Share Posted August 12, 2006 Limiting factor is usually the bearings, too fast and the grease will be thrown out from the rollers. 100A alts have fully sealed ball bearings top and bottom, where as 65A types have ball bearing at the top and a cup roller type at the bottom. Can't remember off the top of my head what the max recommended bearing speed is but its at least 15000 rpm, so with a Tdi you should be quite safe even allowing for the gearing up ratio between crank and alternator pulley sizes... Quote Link to comment Share on other sites More sharing options...
Warthog Posted August 12, 2006 Author Share Posted August 12, 2006 Well between the two of ya, i believe some light has been shed on the matter Cheers Quote Link to comment Share on other sites More sharing options...
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