Power loss when the AC is on
08-30-2012, 04:22 PM
#21
Senior Member
Join Date: 04-04-2012
Location: Sarasota, FL
Posts: 1,307
Don't know if this is 100% true or not, but I've heard that when at WOT with the A/C ON, the A/C clutch will disengage until you are no longer at WOT. Had a buddy try it at the drag strip. Turned the air on and pulled the knob off so he couldn't turn it on...ran identical et.
Again, don't know if its true or not or if it was just a fluke on his part.
Again, don't know if its true or not or if it was just a fluke on his part.
08-30-2012, 04:40 PM
#22
Senior Member
Join Date: 08-03-2009
Location: D.C., Md., Va. area
Posts: 837
Don't know if this is 100% true or not, but I've heard that when at WOT with the A/C ON, the A/C clutch will disengage until you are no longer at WOT. Had a buddy try it at the drag strip. Turned the air on and pulled the knob off so he couldn't turn it on...ran identical et.
Again, don't know if its true or not or if it was just a fluke on his part.
Again, don't know if its true or not or if it was just a fluke on his part.
I have the RPD set to show fuel pressure and just popping the rear of the sunroof will raise it 50 psi or so at highway speeds.
08-30-2012, 08:25 PM
#24
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Join Date: 04-04-2012
Location: Sarasota, FL
Posts: 1,307
08-31-2012, 07:33 AM
#25
Senior Member
Join Date: 07-05-2008
Location: Akron Ohio
Posts: 5,464
Well think about it. It takes more HP to run an AC unit and more HP = more air and more fuel.
If fuel and more power were not added you would feel more of a drop.
This is nothing new as I could always see a similar change in power and MPG in even the V8 engines. In the past it was even worse when all you had was a selinoid to bump up the throttle on the carb in the pre Fuel Injection days.
Alts, Water Pump, Converters/drivelines, Power Steering, AWD, etc all take power away from the car to run. This is why we have electric power steering that was orignally developed for the Fiero. Once it was canceled they found it to be useful in gaining more MPG.
In the old days 1970 and before they used to rate engine HP as Gross HP with engines stripped of everything on the dyno. 71 and later they went to Net HP and it is an engine fitted with the accesories. That is why some of the engines from the 60 had so much power and only ran 14/15 seconds. It was not only the tires that limited them. Todays engines in Gross HP would have some wild numbers under the old system.
If fuel and more power were not added you would feel more of a drop.
This is nothing new as I could always see a similar change in power and MPG in even the V8 engines. In the past it was even worse when all you had was a selinoid to bump up the throttle on the carb in the pre Fuel Injection days.
Alts, Water Pump, Converters/drivelines, Power Steering, AWD, etc all take power away from the car to run. This is why we have electric power steering that was orignally developed for the Fiero. Once it was canceled they found it to be useful in gaining more MPG.
In the old days 1970 and before they used to rate engine HP as Gross HP with engines stripped of everything on the dyno. 71 and later they went to Net HP and it is an engine fitted with the accesories. That is why some of the engines from the 60 had so much power and only ran 14/15 seconds. It was not only the tires that limited them. Todays engines in Gross HP would have some wild numbers under the old system.
09-03-2012, 05:02 PM
#26
Senior Member
Join Date: 08-06-2008
Location: Grand Haven, MI
Posts: 1,761
I can feel it in my V6 and V8 too.
But on the other hand my Fiero V6 is faster by a couple tenths in the quarter mile with the AC on.
Most cars compensate for this with added fuel but there is still a little feel in all of them even the V8. Drag on the engine is drag no matter the cylinders or HP.
But on the other hand my Fiero V6 is faster by a couple tenths in the quarter mile with the AC on.
Most cars compensate for this with added fuel but there is still a little feel in all of them even the V8. Drag on the engine is drag no matter the cylinders or HP.
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