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The S10 4 cylinder began using the Delphi V7 compressor around 2000, maybe earlier. That compressor was manufactured in Dayton Ohio, our C5 compressor was manufactured in Korea. The actual pump assembly is interchangeable. The front and rear castings, pulley, clutch, and control valve are vehicle specific. With the appropriate compressor service tools and knowledge, you could conceivably rebuild a C5 compressor with an S10 and vice versa. Looking at the time and effort it takes to replace a C5 compressor, I would spend the $200+ and buy a new one. Going the other way around, I would definitely rebuild an S10 myself.
Wow ....people are now confusing a/c draw with lack of O2 in the air ....Your car runs sluggish in 115 heat because there’s no usable air to breath ...at night when it becomes much more dense and cool more efficient more effective...not because your a/c is ripping power sure the a/c needs to draw more electrical current to run meaning the car needs to produce a stronger idle to make stronger electrical impulses ...so your alternator is geniusly providing this surge of power the a/c motor is a x hp motor output ....at its spindle to even generate 5hp in a pulley& bearings didn’t require much to compress your cold air ....maybe at best due to the higher ignition a retard your burning more fuel during low loads say town cruising and highways cruising...getting down exceeding a say 2k bench mark ranges should be equal again...so unless your traveling about 93-95 on the highway x eats more gas not power . Just because the pcm makes up for when the a/c is actuated or adjusted ..in its OS ..so while there may a initial intro of say 1- 1.5 hp loss it’s quickly made up for ...vise versa when u turn it off the car may adjust or flutter a RPM go from say 780 rpms to a quick 880 and settle out.
However of the a/c was a fully mechanical operator and the wind speed changed as you accelerate for sure you would be losing power and have one of a cool ride lol .....hahaha !
Last edited by Speedy007; Aug 23, 2020 at 02:21 PM.
Well, better than late than never. Finally got around to doing a little logging on the car. Did a wide open 3rd gear pull with AC off, followed by AC on. On the same stretch of road, same incline, same coolant, intake air temps etc etc.
Surprise, surprise, little to no difference in power. The AC compressor shuts off at 4900rpm per the tune, and you can see slight hp/tq loss in the lower RPM. Max hp delta is less than 10hp. Virtual dyno isn't perfect, but when you keep all the variables the same, it's very reliable and consistent for comparison sake. Very negligible difference in power due to AC running...high rpm definitely within margin of error.
Ignition advance/timing is identical for both pulls.
Tried telling ya ... but u just had to go make some runs lol it was never really about the power loss just about the get and go time lol....excuses I tell ya haha...
If anything the car made more hp with the ac on then off @ 388 ..so it would be a gain the extra ignition and timing adds power of course it does and eats more fuel in return lol .....good job though ...
Last edited by Speedy007; Aug 30, 2020 at 08:32 PM.
I've been needing to do a little logging to fine tune MAF a bit. Already had to log a few WOT pulls so I figured might as well get one with AC on as well. I put on a C6 air intake and used stock C6 MAF table and my trims were within 5 percent basically and wide open AFR was very close too... was surprised it was that close but I'm not complaining.
I did forget to take out the dragy with me, but this was enough data.
Yeah, the compressor shuts off when the system hits full pressure... 400, 450 psi? Something like that. But before then, the car is going slower. What's the difference in 0-60 time?
I think I still standby for you to provide any sort of data/facts vs continuing to talk out of your ***. So much for 50hp loss What about that power loss from timing pull?
I think I still standby for you to provide any sort of data/facts vs continuing to talk out of your ***. So much for 50hp loss What about that power loss from timing pull?
Never ran the car on the dyno. What we saw was cars running around 8 tenths slower ET if they forgot to turn their AC off. I may have been off on my horsepower estimate, but your data actually backs up the OP's feeling and my experience at the track that the car was noticeably slower with the AC on. Peak horsepower isn't everything.
Last edited by sstonebreaker; Aug 31, 2020 at 11:07 AM.
No one argued that AC didn't lose power..... but your 50hp is an order of magnitude off.
I still believe what happens to most guys when they're blasting the AC in the hot summer is heat soak power loss. I watch IATs all the time on my daily driver, and IATs are significantly higher when I run AC, especially when parked or low speed stuff. At highway speed it's about 10* higher with AC, but probably only because on this setup the AC condenser is in front of the intercooler. So it makes perfect sense to me in that drag racing scenario that you'd see a lot of performance loss because of all the prior heatsoaking. Thing would be an absolute dog until you gained some speed and got some cool air into the intake. You're losing way more than 10hp from high IATs (air density loss, any timing pull from high IAT) vs whatever it takes to spin an AC compressor.
Also that's a different car/engine, maybe it was different in it's logic for AC/timing etc.
No one argued that AC didn't lose power..... but your 50hp is an order of magnitude off.
I still believe what happens to most guys when they're blasting the AC in the hot summer is heat soak power loss. I watch IATs all the time on my daily driver, and IATs are significantly higher when I run AC, especially when parked or low speed stuff. At highway speed it's about 10* higher with AC, but probably only because on this setup the AC condenser is in front of the intercooler. So it makes perfect sense to me in that drag racing scenario that you'd see a lot of performance loss because of all the prior heatsoaking. Thing would be an absolute dog until you gained some speed and got some cool air into the intake. You're losing way more than 10hp from high IATs (air density loss, any timing pull from high IAT) vs whatever it takes to spin an AC compressor.
Also that's a different car/engine, maybe it was different in it's logic for AC/timing etc.
Dude, that's what I've been saying all along - the majority of the horsepower loss came from the ECM pulling timing. I NEVER said the majority of the horsepower loss came from spinning the compressor.
As far as the heat soak thing, I agree, that does play a big part. But the fact remains, if you ran your AC all the way to the burnout box and then turned it off, the cars would run several tenths quicker than if the driver left the AC on. That's not speculation, that's just observing what actually happened. So my experience backs up what the OP was saying about his car feeling slower with the AC on. Your power curves back up what I was saying - I see what looks like about 20 ft/lbs of torque loss below 3500 rpm.
I think I still standby for you to provide any sort of data/facts vs continuing to talk out of your ***. So much for 50hp loss What about that power loss from timing pull?
I cannot tell from the vehicle "feel" if the compressor is running or not. Older vehicles with earlier (piston/crank type) compressor technology, you could definitely feel the difference. Modern design rotary compressors are much more efficient. I haven't "felt" the A/C coming on in years.
p.s. of course, if the compressor is on the verge of seizing, you will feel a difference.
Last edited by jackthelad; Aug 31, 2020 at 12:18 PM.
So what’s the final results from this discussion - my car is a ‘98 w/ 38,000 miles -
What mods do you have? Auto or manual? The 94-96 impalas that I'm basing my experience on were all autos.
I'd like to see what a C5 runs at the drag strip with the AC on vs. it off. I'd be willing to bet that a bone stock auto is at least half a second slower with the AC on than off.
So what’s the final results from this discussion - my car is a ‘98 w/ 38,000 miles -
- Less than 10hp lost from running AC directly. timing, fueling identical. AC turns off above ~4850 rpm automatically.
- Majority of power loss is from heat soak/high IAT. Running A/C at low speeds makes this even worse due to the heat created by AC system.
- Old Impalas are slow and even slower when running AC
Ok, can we put to rest that the a/c does not draw 30 to 50 hp? It is much less.
The dyno pull is interesting but does not reflect the maximum a/c horsepower unless you were running the a/c at high blower, outside air, and an ambient representative of worst case where there are Corvettes. I think we have a forum member in Saudi Arabia so let’s say about 120 degrees F by 50% humidity. Let’s also remember that high side pressure typically reduces with road speed up to a point. In that Saudi Arabia ambient and bumper to bumper city traffic, your high side will be quite high. Well into the 300’s psi, possibly higher close to the 400 something high pressure cut out setting. If you were to run your dyno pull under those conditions, you would see a horsepower draw.
Now I’m not suggesting you do this, but if you wanted to see a closer representation of maximum hp difference, repeat your test but block off the condenser with a piece of cardboard (to drive the high side pressure up and keep it up as your vehicle speed increases) and then do your run. Of course you are likely to see your coolant temperature skyrocket too so not a good idea.
What mods do you have? Auto or manual? The 94-96 impalas that I'm basing my experience on were all autos.
I'd like to see what a C5 runs at the drag strip with the AC on vs. it off. I'd be willing to bet that a bone stock auto is at least half a second slower with the AC on than off.
What about that power loss from timing pull?
