Couldn’t find this info consolidated anywhere and none of the Nissan 240SX KA24DE Quest Alternator upgrade articles talk about belt sizes so here it is! I’ve included belt sizes (tested by yours truly!) for use of the Quest alternator with the stock crank pulley as well as the Unorthodox underdrive crank pulley. I’ve tried in both cases to use the old alternator belts but struggled with it for hours before getting the next size up. It’s still a VERY tight fit but it will go on! All belt sizes listed use Gates part numbers:
Stock crank pulley:
Air conditioning K040355
Stock alternator K040305
Quest alternator K040310
Power steering K030395
Unorthodox underdrive crank pulley:
Air conditioning K040340
Stock alternator K040285
Quest alternator K040292
Power steering K030385
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FYI, here are my voltage readings with the Unorthodox underdrive crank pulley at idle with low beam headlights off and on:
Stock alternator:
Low beam off 13.4V
Low beam on 12.15V
Q45 alternator:
Low beam off 14.4V
Low beam on 14.2V
