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Those with Alternators making a LOT of power will lose horsepower. The power has to come from somewhere.

That's why hardcore performance guys put under drive pulleys on their alternators. It reduces the power that the alt steals from the motor. If you have a big V8 or Diesel then you probably won't notice the drop in HP but those with a smaller engine might.

Yea what I was thinking. I have an pully like that. Mechman guy I talked to told me about it. But, he called it something else I believe. Now, putting in a bigger alt I can see. But, they said with all stock electrical. Weight is the only cause to me on stock. And not really loosing horsepower as it is more/to much weight ya car has to try to move. Like I said I have a 122cid 4cyl sohc and Since day 1 I have had my system in it. SO, now I am curious what it will do if I took everything out.

No no, what you have is an OVER-drive pulley. Its smaller than the stock one (so it spins faster) so that when your engine is at idle the alt may be spinning at 1500rpm still. An UNDER-drive pulley is BIGGER than the stock one so it barely spins and hardly sucks any juice from the engine turning.

The alternators take the turning of the engine and turn that motion into electricity so naturally the more alternators you have the more power (horsepower) they take to turn. Remember, NOTHING is free on a car. You add something to the belt system, it's gonna take power to turn it.

EDIT: to the reply above, is that standing weight or rotating weight? Rotating weight is what you want to get rid of first.

Idle rpms are 1000. But, it is bigger then the stock one. Im good when it comes to working on stock. But when it comes to all these add ons, I am still learning these things. I am not afraid to admit I am still a noob on a lot of the big system builds. I got a lot of help from here. Great group of people here. And mechman 220 amp focus svt alt with the bigger pully under it. Sorry I dont know to much about that. Im trained in a lot of areas on vehicles. Just now learning what needs to be done for the big systems.

Oh my bad then. I've never seen an aftermarket alt come with a bigger pulley.

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in drag racing the theory is every 100lbs you can get rid of is the same as adding 10hp. It works the other way too. Do the math. It doesn't actually take away hp, Just that the HP is wasted moving the extra weight.

Well I know in drag racing the more hp ya add usually the more weight ya add. So ya have to find out how to lower the weight to help with the added hp. Aluminium engine parts a lot of the guys cars I work on at the drag track use. Say it helps a lil with weight and keep added horse power. Well should say friends cars.

Current system (still building) 2 kicker 12" dcvr in factory kicker ported box, Rockford Fosgate 1200.1 Amp, Kenwood ddx-470 ddin radio, Rockford Fosgate 0 Gauge wiring, Rockford Fosgate punch 6X8 2 way speakers.

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