Car is killing alternators

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Jan 2, 2004
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AFAIK, racers use smaller alternators to provide just enough power to keep the battery charged and provide for lighting/ignition. And in your case, your engine is spinning more than usual road car. I don't know much about underdrive pulleys but my brain is saying wiring problem or simply bad alternators. Genuine Mitsu alts are known to be fairly durable, internally regulated. How are the alts dying - mechanical failure from high RPM operation or electrical failure like the regulator getting fried?
 
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Jan 24, 2018
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i didnt have time to read all the posts. but it looks like you need to check ALL your grounds. I.E. wires
 

Spetz

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Thanks guys, I was hoping to get advice on what I should be testing? As far as the alternator spinning fast, the engine is standard as is the alternator, so it is not doing something outside of factory duties. I know of course it is on a race track, but even at 65mph the engine revs around 3,500rpm standard, so it was always been a high revving engine. The ECU tells the alternator when it needs to "work". I have replaced ECUs and this issue persisted (i.e., an alternator failed after that too). The alternator does not have a clutch
 
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Kah-nah-dah
Unless you are wildly over revving the engine, an under drive kit could cause you more problems. How is the alt dying? Front bearing problems? Check the tensioner first, then check the quality of bearings. Those chinese 6203 or 6303 bearings can be pretty craptastic. Is the regulator dying? Do you have something that's applying sudden massive load? Yes or no... Add a dedicated ground strap from a mounting bolt for the alternator to the frame. Also check the positive cable leading from the alternator output to the fuse box then to the battery. RSX that loved to kill alternators, was cured with extra ground. GM cars that ate their alts because of cheap 12Ga positive cable from alternator, causing the regulators to cook. Many 'new' and remanufactured alts using cheapest bearings available. I've spun some mitsu alts hard, engine redline at 7500rpm, stock pulleys, and I haven't popped one. Faster an alternator spins the more actual power you can pull from it easier. That's why at idle an engine will grunt when you turn everything on, because the alternator is struggling to keep pace. Then when you spin up the engine, the lights brighten, the blower motor speeds up, because the system is actually discharging or barely able to maintain charge level. For doing it properly... What is the diameter of the crank pulley? What is the diameter of the alternator pulley? What's the redline of the engine?
 
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