If your 911 has a carb without an engine management computer system I would agree with you. But that's not case in modern vehicles. Your seat of the pants drive experience might feel like it runs better but it's really running as it should. Now tire temperature and rating would have an impact on your how your 911 feels in colder or hotter temps at some speeds...

I'm not trying to argue with anyone but this isn't just my opinion.

Cheers...happy motoring!

 

So do mine. Its normal.

 

That being the case, and let's assume for the sake of this discussion that it isn't a seat of the pants issue, what other mechanical issue might cause a decrease in performance in hot humid weather vs. cooler, less humid weather.

 

As a follow up note, yesterday remained very hot, but significantly less humid and the car was running very well. My hunch is that the humidity is the culprit and that, whatever the effect on combustion, the ECU cannot compensate for this.

 

Funny how everyone's butt dyno feels different...
I personally think my cars' performance increases on rainy (humid) days

Or it could be that Im still driving at my normal speeds and everyone else has slowed down .

But seriously, Im always baffled by why my cars (not just the 911) seem to be more torque-y on rainy days as compared to others.