really how much does having your AC on mess with HP?

**greatwhiteZ28** · 08-30-2007, 04:20 PM

just want to know the loss,

and heard that you can mess up your AC compressor or something if you race with AC on . or by turning it on or off while gunning it???

**mnypitZ** · 08-30-2007, 04:33 PM

The a/c shuts off at WOT. It shouldnt matter.

**greatwhiteZ28** · 08-30-2007, 05:18 PM

could be a fluke but the first SES light that turned on my car was after i raced this guy and PROCESS WAS.... turned off AC before race, but when got done with that race and was coasting around 130 turned backed on and instantley SES light came on. like said casuld be a fluke, but

still would like to see the #'s that AC takes off total HP #'s

***Ed Blown Vert*** · 08-30-2007, 05:22 PM

Originally Posted by mnypitZ

The a/c shuts off at WOT. It shouldnt matter.

Thats correct.

Disable RPM = 4294
Enable RPM = 3950

Disable TPS = 100%
Enable TPS = 0%

**greatwhiteZ28** · 08-30-2007, 05:25 PM

thanks "ed blown vert" does that mean that if the AC is on when ytour gunning it it will trn off at 3950 rpms ?

**Rikki_SeVeN** · 08-30-2007, 05:28 PM

I broke my A/C compresor... stepping on it... while it was on... and I only did it twice... it shots off... but not nearly quick enough... sometimes the power of the engine just overwelms it... especially if it burns out and the RPMS clim real quick

anyways on a V8 like that it doesn't take away much at all... and it does eventually shut off... so it doesn't mater in the top end of the Rev Range

My sudgestion...is just turn it off... before racing... saves you having to go to the Mechanic...to have your compresor changed... (BIG MONEY)

**JonB** · 09-04-2007, 07:17 PM

Originally Posted by Ed Blown Vert

Thats correct.

Disable RPM = 4294
Enable RPM = 3950

Disable TPS = 100%
Enable TPS = 0%

What about at lower rpms like from 1,500-4,294 when it shuts off. Not that I race with my a/c on but just curious what the lose is with the a/c on. I would think on a dyno if you were to run with the a/c on once you hit 4,294 and kept the TPS under 100% you would have some kind of spike in the hp/tq curve. I really don't notice too much of a difference in power with a/c on vs off unlike some 4cyl were it feels like you lost half the hp of the motor. Just curious.

**Firebirdjones** · 09-07-2007, 10:06 AM

Ed is correct, I see the same specs in my Hptuner software. Although I am not sure if both of these setting have to be met or not for this to happen?

I don't have HP numbers for you but I can tell you I have ran my chevelle with and without the air on just for giggles.
Without the air it runs 11.40's at 118 mph,,,,with the air on the car slowed to an 11.69 at 115 mph,,,,big difference in that car,,,but is uses the older style compressor that is not as efficient and takes quite a bit of HP to turn, plus this style (in 72) does not use a pressure switch, so the compressor does not cycle on and off throughout the run,,,,it's on all the time.

I guess I could do the same test with the 02 SS by changing the setting in HPtuner to keep the air on all the time,,,but I just haven't messed with these settings. What I may do is lower these settings on mine to make the air turn off sooner. Thought of setting TPS to around 80% and lower the RPM to around 3,000 to 3,500 rpms just to experiment with it. Larry.