A/C - in a crapcan race car

It is, as best I can tell, universally practiced to remove the entire A/C system on EVERY road race car build. Then we go to races where it's 100F+ ambient and drive around with our adrenaline at full tilt wearing a double layered snowsuit, requiring our sharpest concentration for 2 hours straight while our pit crew eats ice cream. A lot of teams address the heat issue with ventilation systems, cool shirts, ice packs in their pockets etc, all of which are not insignificant weight, and, more importantly IMO are another thing for the driver to have to hook up and mess with when doing a driver change. It seems to me that, on my next Chumpcar build, I'm going to leave the functioning climate control in place, and simply duct all the air up the back of the drivers seat and have it blow out through the seat directly into the driver's torso, and add a port for the helmet brain sucker. That seems simpler to me. No ice to refill. No shirt to hook up to an aquarium pump. There's a clutch that cuts out the AC at WOT anyway, so in practical terms, there's no real loss of HP even.

So why does EVERYONE immediately remove the A/C?

sporqster wrote: So why does EVERYONE immediately remove the A/C?

"Add lightness."

Easy 80-100# gone in a few short minutes.

add lightness + MOAR POWAH!

In reply to Ranger50: really? 80-100#? I would have guessed it to be more like 20-30# - putting it in the same range as the ice cooler.

I removed it from my first Miata track car. I also put gauges in two of the HVAC vents.

Learned my lesson and left it in the second car.

Ranger50 wrote:

sporqster wrote: So why does EVERYONE immediately remove the A/C?

"Add lightness." Easy 80-100# gone in a few short minutes.

There is no way the AC system can be #100.

My question is, can you remove the heater core and leave the AC stuff so that it still works?

I have the whole system intact in my track car, but if I could remove even #25 by removing the heater core and related stuff, I would do it.

Weight, and because the compressors don't last. Over revving is one of the number one causes of compressor death. I've killed a number of them. That said, if you underdrive it, it should last longer.

I have already decided to reinstall the A/C system when I do the engine swap on the RX-7. No A/C means I don't drive it all summer.

sporqster wrote: In reply to Ranger50: really? 80-100#? I would have guessed it to be more like 20-30# - putting it in the same range as the ice cooler.

You have the whole heater/ac box gone, hoses gone, compressor gone, condenser gone.... That evaporator in the heater box weighs a TON, even though it is aluminum. Compressors aren't light either.

Toyman01 wrote: Weight, and because the compressors don't last. Over revving is one of the number one causes of compressor death. I've killed a number of them. That said, if you underdrive it, it should last longer. I have already decided to reinstall the A/C system when I do the engine swap on the RX-7. No A/C means I don't drive it all summer.

Is that easily done? Underdriving it.

I would imagine finding a bigger diameter pulley to accomplish that would be difficult.

You're describing exactly what the ALMS Corvette racing team did. They used a Chevy Volt AC compressor because it was light and efficient.

A/C has been done "Lemons style" by a number of teams in the past :D

As far as practical use of original equipment AC, I imagine the compressor wasn't designed to be wound up to redline over and over again for extended periods of time. Would be bad news for the thing to seize up and throw a belt mid-race if you were in contention.

In reply to Slippery:

Easier to find a smaller pulley for the crank. A lot of vehicles they make underdrive kits for.

Toyman01 wrote: In reply to Slippery: Easier to find a smaller pulley for the crank. A lot of vehicles they make underdrive kits for.

I'd go about it this way as well. Put it on a seperate serp belt than other systems in case of failure/seizure/belt chucking.

For enduro purposes, mental composure and coolness likely outweight the 10/10ths performance benefit of added lightness/power robbing (assuming decent HP to begin with). Go slow to go fast.

There is also the philosophy that it takes some of the available engine power to run the compressor. Removing it frees up that lost power for use.

But in saying that, sometimes comfort takes preference over that power.

wlkelley3 wrote: There is also the philosophy that it takes some of the available engine power to run the compressor. Removing it frees up that lost power for use. But in saying that, sometimes comfort takes preference over that power.

Aside from the weight though, if it's really a dog fight, you could always turn the A/C clutch off and free the HP up.

I'm not saying it's a terrible idea, but this car is noticeably slower with the AC on. I'm recharging the AC today, so we'll see what it's like with the 5 speed, but with the auto is was a total dog with the AC on.

So work hard somewhere else on the car to lose the extra weight... I like this idea.

GameboyRMH wrote: You're describing exactly what the ALMS Corvette racing team did. They used a Chevy Volt AC compressor because it was light and efficient.

You have any supporting info? I used the google and couldn't find anything. I have my doubts because the Volt AC compressor is a high voltage component, and I doubt they would have added high voltage to the ALMS car just for the air conditioning pump. I could totally understand other parts of an AC system (evaporators/chillers, condensors, etc.) but the actual high voltage pump itself would be surprising. If you have other info, you'd be doing me a favor to share some links. Thanks!

Bryce

I read somewhere it takes 15-25hp to drive a A/C compressor. That's pretty noticeable, not to mention the hit in economy. Not a big deal in a sprint race, but in an enduro it could cost you a stop or two. Still worth it to me. I'm getting to old (and fat) to deal with 120+ temps in any car.

I'm thinking it's because the AC systems are typically busted on the crap cans people are turning into crap can racers.

I LOOOOOVE the idea of A/C in a LeChump car. The "Punisher" Crown Vic guys did it the first year we were there. Car was fast as berkeley. Being hot is absolutely my least favorite part of racing. I get all claustrophobic and dizzy.

The a/c system will cut out at WOT anyway. Is it really going to work? probably not.

The biggest reason (I think) is that there is more heat that the CAR needs to shed this way. That big condensor needs to go somewhere. Also, the engine will produce more heat due to the increased load. Fuel mileage will suffer a good bit too I would think.

Notice I never said anything about weight. I don't think it is about weight. At least for my team it is not.

If you want to cool the driver and not worry about driver change complexity, make a cool seat. Basically it is the same thing as a cool suit / shirt except it is sewn into / attached to the seat. You still need to refill the cooler every now and then, but it is not as difficult this way.

Rob R.

In reply to wvumtnbkr:

Great idea on the cool seat

wvumtnbkr wrote: The a/c system will cut out at WOT anyway. Is it really going to work? probably not.

You sure about that? Sure, on most modern cars it does, but I don't recall the compressor ever kicking off at WOT on my E30. Any time I need to get around someone quickly, I'd temporarily turn the AC off, because it's noticeably slower with it on. Sure, it would be easy enough to make a WOT switch that opened the AC clutch circuit, but I really don't think the E30 compressor kicks off in stock form.

Well I take it out of drag cars because, weight of course and then you can't run it on the track anyway without it dripping water everywhere.