{"product_id":"175a-powermaster-851574-1-alt-denso-black-6-grv-hpr-1-wire","title":"175A Powermaster 851574-1 Alt Denso Black 6 Grv HPR 1-Wire","description":"\u003cp\u003eMost people are familiar with the alternator rating as the amperage rating.\u003c\/p\u003e\u003cp\u003eAlternators are referred to as a 65 amp or 100 amp alternator.\u003c\/p\u003e\u003cp\u003eWhen replacing the alternator on the family car, this information is likely all that is necessary.\u003c\/p\u003e\u003cp\u003eHowever, when building a custom car from the ground up, a deeper understanding of the power curve of an alternator is required.\u003c\/p\u003e\u003cp\u003eA custom pulley or so-called 'power pulley' set is usually used with a performance alternator.\u003c\/p\u003e\u003cp\u003eA mismatched pulley ratio and alternator can cause issues, especially at idle speeds where alternator performance is critical.\u003c\/p\u003e\u003cp\u003eUnderstanding the alternator's capability at slow speeds is important to avoid this.\u003c\/p\u003e\u003cp\u003eAn alternator's output depends on speed, but this can be misleading because the output is not linear.\u003c\/p\u003e\u003cp\u003eInstead, it follows a curve.\u003c\/p\u003e\u003cp\u003eEach alternator has a unique curve, and at idle, small changes in the alternator's speed can significantly affect its output capacity.\u003c\/p\u003e\u003cp\u003eBecause of this, pulley ratios are very important, especially when using high amperage alternators.\u003c\/p\u003e\u003cp\u003eThe pulleys supplied with the alternator are matched to the winding and power curve.\u003c\/p\u003e\u003cp\u003eIt is crucial that any dress-up pulley sets do not deviate from this ratio.\u003c\/p\u003e\u003cp\u003eTypically, a street-driven car should have a pulley ratio of at least 3:1.\u003c\/p\u003e\u003cp\u003eIf the vehicle has an automatic transmission with a low idle and spends a lot of time cruising, then a higher pulley ratio - perhaps 3.5:1 - should be used.\u003c\/p\u003e\u003cp\u003eAlternators can handle high speeds up to 20,000 RPMs for short periods, so overdriving the unit is not an issue.\u003c\/p\u003e\u003cp\u003eThe output of high amp alternators can drop off significantly under 2400 rotor RPMs.\u003c\/p\u003e\u003cp\u003eTherefore, Powermaster does not recommend power pulleys with high amp alternators.\u003c\/p\u003e\u003cp\u003ePowermaster employs a state-of-the-art computer alternator dyno to measure the performance of each alternator manufactured.\u003c\/p\u003e\u003cp\u003eOutput curves, engine idle speeds, and alternator pulley ratios are carefully considered to ensure good drivability at idle and slow cruising speeds.\u003c\/p\u003e","brand":"Powermaster","offers":[{"title":"Default Title","offer_id":51739779006746,"sku":"PRM851574-1","price":380.69,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0975\/8942\/8506\/files\/51WPGljLugL.jpg?v=1771872667","url":"https:\/\/trybeepbeep.com\/products\/175a-powermaster-851574-1-alt-denso-black-6-grv-hpr-1-wire","provider":"TryBeepbeep","version":"1.0","type":"link"}