Effect of AC on engine output?
Discussion
Took the old girl for a blast this evening and forgot I had the air con blasting away on level 3. When I finally realised, I turned the AC off completely, hit the loud pedal and the increase in power was astonishing. Does anyone know roughly how much power the AC robs when you're giving it beans?
Interesting.
The U.S. Nobles come with an AC bypass switch that disengages the AC compressor during any major acceleration "events". So you never feel the AC drag on power when you need it.
These bypass switches are pretty simple devices that are available for most cars aftermarket.
The U.S. Nobles come with an AC bypass switch that disengages the AC compressor during any major acceleration "events". So you never feel the AC drag on power when you need it.
These bypass switches are pretty simple devices that are available for most cars aftermarket.
Edited by JLSELAN on Sunday 18th July 22:13
JLSELAN said:
Interesting.
The U.S. Nobles come with an AC bypass switch that disengages the AC compressor during any major acceleration "events". So you never feel the AC drag on power when you need it.
These bypass switches are pretty simple devices that are available for most cars aftermarket.
Is that not the same as turning it off?The U.S. Nobles come with an AC bypass switch that disengages the AC compressor during any major acceleration "events". So you never feel the AC drag on power when you need it.
These bypass switches are pretty simple devices that are available for most cars aftermarket.
Edited by JLSELAN on Sunday 18th July 22:13
sundance02 said:
jamie g said:
I can't say I notice any difference in performance, the revs drop a little at idle though.
I'm sure it only takes a few bhp, 15% power loss doesn't seem right unless you are in an 850 mini or something.
If you have the a/c on full a 10% loss is easily achieved, it will also depend on the type of system fitted. On a diesel it is not so noticeable. I'm sure it only takes a few bhp, 15% power loss doesn't seem right unless you are in an 850 mini or something.
SimonJW said:
Is it not more to do with the drain on the battery?
No. Purely the extra force needed to spin the compressor.Stating how much power it takes as a percentage of engine output is daft. Clearly aircon will use roughly the same power sat at idle as when flat out.
I suspect the widely quoted 10-15% figure is from people running around in small Fiats on holiday in Spain. If they output 50bhp in heat you're lucky!
sundance02 said:
M400DPC said:
Took the old girl for a blast this evening and forgot I had the air con blasting away on level 3. When I finally realised, I turned the AC off completely, hit the loud pedal and the increase in power was astonishing. Does anyone know roughly how much power the AC robs when you're giving it beans?
Makes a huge dif on any car, will drain 10%-15% of your power, and if you open the window that kills the air flow round the car in a Nob, so if you wanna go fast you just have to sweat. 
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