How much power does an alternator produce

you'll need to contact the manufacturer... every one has a different spec for the question you're asking. The alternator I just got had a "dyno sheet" inside.

 

If this thread is related to your "battery" thread, you have less options for alternators in an S60 engine.
The best I have found (so far) is a Delco 36SI. It's 170AMP.
(High output at idle -100 Amps at 2000 alternator RPM presuming around 750 engine RPM with the correct pully)

 

http://www.delcoremy.com/Alternator-Models/22SI-HP-Heavy-Duty-Alternator.aspx
Here is a link for a common 22SI. You'll see it is rated for 150 amps, but it reaches 150 amps at about 4500 rpm. No truck engine will ever turn that fast, but the belt an pulleys size ratios do make the alternator turn much faster than the engine. Your question is too vague. The truck model really doesn't tell anything about the model of alternator, could by anything. Like BullDoggin said, you are going to have to find out what model of alternator it is, and then find your alternator drive ratio vs engine rpm to calculate what speed your alternator is turning at 900 engine rpm and then consult the manufacturer rating chart.

 

An amp meter won't tell you anything, unless you can load the charging system to its full capacity... an alternator only produces what the system is using.

 

In theory, no, it will not change MPG if you do not use any more power. I'm sure there will be a difference in unloaded power use due to heavier wingdings, magnets, etc., but that will most likely be so small that it wont be measurable. That is assuming that both alternators are comparable in efficiency.

An alternator does not produce anything, it converts, think of it more as a transformer. It transforms mechanical energy into electrical energy. How efficient it does this will determine if it takes more power from the crank or not. It is very possible to replace a 150 amp alternator with a less efficient (cheap) 135 amp alternator and have it draw more power from the engine. The point is that when you compare alternators, make sure you compare apples to apples. Quality alternators will publish efficiency in some way. Off brand cheap ones will usually boast about amps, but wont tell you efficiency. If an alternator come with a dyno sheet, it's a good indication that they put some time into making it more efficient.

 

I've got a 35 SI rated at 135 amps. When I turn on EVERYTHING on the truck I can find to turn on, lights, fans, AC, etc. I am pulling 65 amps with all incandescent lights on the truck when I put my ammeter on the alternator power wire.


That includes putting a vacuum, computer running a test pattern and 20v lithium battery charger on the 1500W power inverter.

 

I just had my alternator replace on Thursday night. It just quit charging, I called the broker's shop and they had one in stock. So they replaced it within an hour and lost no downtime. Anyways, I found out they replace it with a BOSCH AL9960LH. It puts out 160 amps and 80 at idle with a 2 yr warranty. I have read the reviews on this alternator and all seem good. Also I kept my Leece Neville core and plan to have it rebuilt at an electrical shop for a back up. Does anyone have any feedback on the BOSCH 9960 ?