Even though i've noticed it before today, today it got me thinkin. I was in third gettin on the freeway. It was about upper 80's and i was right on the coast, so alititude isnt a factor. AC takes a lot of power outa that 2.0 Anyone have numbers or an idea of how much hp or torque is lost, if thats even possible. No big deal, im just curious.

 

I kind of doubt someone would pay the cash to get a dyno run of thier car with the ac on and with it off. Unless they have alot of cash to burn. haha.. Just realize that the ac works the car harder robbing a small amount of power. Thus the reason you feel the lag.

 

i would imagine it's like 1-2hp.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Kal &raquo;</TD></TR><TR><TD CLASS="quote">i would imagine it's like 1-2hp.</TD></TR></TABLE>
Yea it's not alot

 

IIRC, a few years ago someone tried this with a Prelude and it was 6-8hp @ the wheels with the 2.3l vtec motor.

 

The AC works when not needing full power. The computer has a cut-out for the AC at full throttle.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SilentBob-RSX &raquo;</TD></TR><TR><TD CLASS="quote">The AC works when not needing full power. The computer has a cut-out for the AC at full throttle.</TD></TR></TABLE>

wow, thats very interesting
i have noticed that when i got my ac on and i floor it the air isnt as cold.

 

That is badass. I never knew that. I don't use ac anyway. Its uses gas and that stuff is not cheap.

 

ive seen a 00 si loose 14 hp on the rollers with the ac on

 

I was just poking around some threads in the dyno forum over at k-series.com and stubled accross this post.

Since you have to register to view threads there, I will quote it here.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fsugatorbait from k-series.com &raquo;</TD></TR><TR><TD CLASS="quote">
May 2, 2004 - 73.9 degrees, 29.63 barometric pressure.

Mods:
AEM CAI
Comptech Header
Megan Test Pipe
Greddy Evo
Hondata flash

Got 4 pulls, unfortunately only got printouts so I cant post graphs, here's the results...

1st pull 3rd gear: 156 hp 132 tq A/C on 3:26 pm
2nd pull 3rd gear: 158 hp 132 tq 3:28 pm
3rd pull 4th gear: 152 hp 132 tq 3:31 pm
4th pull 3rd gear: 157 hp 131 tq 3:32 pm


Very pleased with the #'s and had my tail sniffed too to check how well hondata did with the A/F ratio. Found I was running pretty lean; at 4250 rpms I was at 15.4 and at 5750 rpms it spiked up to 14.7, but after 7k rpms it dropped down into the low 13's to mid 12's. Also found out that my rev limiter is 7900 rpms, instead of what they claim at 7700.

Ill be going back with the DC Race header and Fujitsubo RM-01A exhaust within the next week or so to see how it compares.</TD></TR></TABLE>

Note that he had the AC on durring his first pull, and it seemed to have very little effect (if any) on his numbers. This was on an EP3 BTW.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Gabe_ &raquo;</TD></TR><TR><TD CLASS="quote">

Note that he had the AC on durring his first pull, and it seemed to have very little effect (if any) on his numbers. This was on an EP3 BTW.</TD></TR></TABLE>


I don't agree. The ECU would have shut off the signal to the A/C compressor clutch on a full throttle dyno pull. There would have been no parasitic loss at that time because the compressor was not operating.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jim Truett &raquo;</TD></TR><TR><TD CLASS="quote">


I don't agree. The ECU would have shut off the signal to the A/C compressor clutch on a full throttle dyno pull. There would have been no parasitic loss at that time because the compressor was not operating.</TD></TR></TABLE>

The ECU shurts of the AC compressor under WOT? If this is the case, shouldn't the answer to the original poster's question be ZERO? And then what are all of these other people talking about who are saying they witnessed large losses? Does the ECU only do this on K-Powered rides?

 

With A/C at full power, 10-15% POWER LOSS IN MOST CARS

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Gabe_ &raquo;</TD></TR><TR><TD CLASS="quote">

The ECU shurts of the AC compressor under WOT? If this is the case, shouldn't the answer to the original poster's question be ZERO? And then what are all of these other people talking about who are saying they witnessed large losses? Does the ECU only do this on K-Powered rides?</TD></TR></TABLE>

You would need to be at least 75% of throttle position for it to disable the AC. Most vehicles with EFI systems have some kind of TPS or load based AC control.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jim Truett &raquo;</TD></TR><TR><TD CLASS="quote">

You would need to be at least 75% of throttle position for it to disable the AC. Most vehicles with EFI systems have some kind of TPS or load based AC control.</TD></TR></TABLE>

I was unaware. Good to know

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Slo2 &raquo;</TD></TR><TR><TD CLASS="quote">ive seen a 00 si loose 14 hp on the rollers with the ac on</TD></TR></TABLE>

I have seen a 2000 GSR lose 15hp and a 1999 Si lose 13HP with the A/C on

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Kal &raquo;</TD></TR><TR><TD CLASS="quote">i would imagine it's like 1-2hp.</TD></TR></TABLE>bingo

 

I think the cut off is at 5000 RPM.

 

What a worthless thread. So far we have a bunch of different people throwing out a bunch of different answers with no proof.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Gabe_ &raquo;</TD></TR><TR><TD CLASS="quote">What a worthless thread. So far we have a bunch of different people throwing out a bunch of different answers with no proof.</TD></TR></TABLE>

It's not a simple test. Someone would need to intentionally enable the compressor at WOT to test power loss on a dyno.

 

At work, we call it "reverse engineering"

 

Ive heard that in the general automotive world,about 10% of your power is lost due to the A/C running.