WOT will have the compressor turn off, so I cannot imagine you could measure the difference. I would say ~1% for AC. It's such a small difference there is no MPG improvement free with it on or off.

 

a/c on = massive torque lost. which i dont like =(

 

Having the a/c compressor turn off at WOT is best but a lot of older Hondas didn't do that. I'm not sure if the S2000 did this or not.

 

I'm pretty sure the compressor stays on at WOT. My Mazda 3 even cut it off at WOT, why the s2k doesn't idk.

 

Oh it certainly cuts out. Go for a [legal] high speed cruise one night and at about 95-105 Mph the revs are 5-6k, and you will start to get very, very hot inside that car. The A/C clutch disengages to prevent rapid wear. Any vehicle that has a rev range like the s2000 would be wise to incorporate this feature.

 

Hmm guess it's just not as obvious. Guess I'll stop hitting ac button when I drive to redline

 

This is why in a near future I wanna have an electric motor running my belt so the engine don't lose any power..

 

^ nothing for free

 

I think we have a high RPM cutoff, like 7K or thereabouts, but no WOT cutoff. I don't have a source to cite though.

 

I don't believe that will work, sadly. Let's assume it takes the aforementioned 5HP to turn the compressor. Google says 5HP is 3728 watts, or 310 amps at 12 volts! And that's not even accounting for startup amps...

Plus, like starchland said, there's no free power. Even if you could do it with an electric motor, it would just transfer the load to your alternator.