I want to run a 1000 watt load off an inverter at a job site. I have one of those inverters that comes with jumper cables to run right off the battery but now I'm wondering if the alternator will be able to keep up. How much will the alternator put out at idle (or will the vehicle rev up if need be?) By my math a 1000 watt load is going to be ~80 amps.

I may be running it for a few hours so it would be a problem if I was slowly draining the 4Runner's battery.

Ideally I would have a small generator for this but it's not going to happen on short notice.

I doubt that you will be using all the 1000 watt constantly on a construction site, that is if you are using power tools (drills, saws, etc), they are used for a few minutes then the are off for a while. Thus, there will be no problem. Also, I doubt you will be using all the 1000 watts. Most power tools are far less than than that.

The car will not automatically rev up if the alternator cannot keep up with the load; you would have to do that manually which I doubt you want to do.

You might want to get a voltmeter and check the voltage from time to time. You can get some that plug into the cigarette lighter socket. If the voltage is constantly below 12 volts, the alternator is not keeping up.

Following. I'm also interested in a good tire compressor if anyone wants to chime in.

I like this tire compressor:

STEEL Vs. ALLOY WHEELS Which One Is Stronger? Hydraulic Press Test! - YouTube

I omitted the boring details but yes it is a 1000 watt load (8 amps @ 120v) and yes it will be running constantly. Not a power hand tool. So I do need to know at least the ballpark of what output I can expect from the 4Runner's alternator.

I do have a multimeter so that's a good idea of checking on it periodically so at least I don't end up with a dead battery.

Have you looked through this thread?: Getting more current from your stock alternator at idle

i have the high flow compressor which i really like. i used the small cheap ones before and man, i was pumping my tire for 40 minutes after i went to the beach. lol. if you need to buy one, get the high flow one, just like what i have here. Smittybilt Tire Pump and Fridge mods using a powerpole connector instead of the cigarette outlet - YouTube

I did see that thread, but if you're going to go to al the trouble to get the accessory belt off and get a custom pulley for the alternator I would rather just get a HO alternate and not worry about running a stock one at 150% of its expected RPMs.

I'm really just asking what is the usable amps I can get from the stock alternator at idle, after the vehicle has taken what it needs to run the ECU etc.