A/C - in a crapcan race car

Toyman01 wrote: 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.

Ding! Not racing related, but I've been researching ways to install A/C in my Mini and GT6, especially now that we've entered the "cars stay in the garage from late June thru Aug season."

That said, A/C is definitely a load felt on low HP cars like my TDI with its meager 90 bhp. There's a mpg hit as well.

Besides the mentioned heat load, I'd also want the reduced complexity in a race car - more crap in the engine bay to work around.

I found this article from R&T: Chevrolet Corvette ZR1 vs C6R.

Towards the end there was this blurb about the A/C in the C6R:

"There's no passenger seat, and that side of the car is filled with air conditioning, drink bottle and electronics. Interestingly, the rules require air conditioning. The C6.R uses a compressor from a Cadillac SRX that's driven off the propshaft. The cold air is routed directly into a custom-made seat to more effectively cool the driver."

The article is from 2012.

I've seen similar descriptions of driveshaft-driven ac compressors in endurance racing cars. I think there may be a FIA rule about cockpit temperatures.

Most cars cut the a/c clutch off at WOT over a certain rpm. SOME cars don't.

I live in Texas and AC is worth about as much as every other car attribute combined. There are summers where i literally dont bother to get a car running because i'd still have to fix the AC after getting it running or it would just sit there and not get used anyway.

Ac systems do NOT weigh 100 lbs. Or anything even close. I think 50 is about tops.

If i were running ac on a race car (which is a great idea), the problem i see right now is that i'd be tempted to change almost everything about the stock system. The a/c compressor, most of the lines, and the evaporator COULD stay stock, but id be sorely tempted to relocate the condenser somewhere that didnt share airflow with the radiator because a hot condenser DOES diminish the ability of a radiator to shed heat into that airflow. Moving the condenser means changing the lines AND adding its own separate fan (unless you dont expect it to work in the pits). The evaporator could stay in the stock location but i'd almost certainly be hacking up the stock HVAC 'box' to remove the heater core and most of the flaps and doors and adapting the output to some DIY ducting. And, id definitely use an underdrive crank pulley to slow down the compressor, and i'd have to re-wire the a/c clutch circuit so that the ECU wouldnt try to turn it off at high rpm, but id still incorporate low and high pressure cutoff switches in the circuit. If a condenser fan existed id probably just relay it off the clutch coil circuit so it ran whenever the clutch was engaged.

So yeah, good idea, but it would be a lot of work to do some of the mods id want to do for it. If you left a totally stock system on there you'd just have to modify the clutch coil circuit so the computer doesnt turn it off, and put an underdrive crank pulley on, and hope the added heat doesn't push your cooling system over the edge.

Try rolling all of your windows down and see how well the A/C works.

Is it dry enough for one of these?

I like the idea of A/C in a racecar. The ones I've driven lacked it, or a cool suit. After 10 laps I've gone from amped up and excited to dizzy, nauseous and just wanting the berkley out of the car.

Older cars have heavier, less efficient (more power sapping) systems than newer cars. A powerful car with a good system wouldn't be a big penalty. A comfortable, alert driver is well worth it.

Some creativity could really down size the system. If your just blowing air into a seat or suit system, I seems you could get away with a smaller compressor/condensor/evap

...or just stash some dry ice in your firesuit

xflowgolf wrote: 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.

This car was built as an endurance racer. It still had the AC, full heating system, wipers and even the heated mirrors. And their presence was directly responsible for it winning a 3 hour race at Watkins Glen when the rain and fog made it hard to even see the corner stations.

Gearheadotaku wrote: I like the idea of A/C in a racecar. The ones I've driven lacked it, or a cool suit. After 10 laps I've gone from amped up and excited to dizzy, nauseous and just wanting the berkley out of the car.

This is my problem. My last Lemons stint I kinked one of the cool suit hoses when I strapped in. What should have been a 2.5 hour stint, I cut short, to a little over an hour. By that time I was wiped out to the point of making stupid mistakes on track. The heat just sucks all the energy and fries the brain.

A/C or a cool suit is a must for me.

Some of the major race organizations require AC in a closed car.

Run an underdrive pulley on the crank will slow things down.

ya wussies!

We drove 2.5 hour stints at Summit last month and had no problems. We don't have A/C or a cool suit.

Rob R.

wvumtnbkr wrote: ya wussies! We drove 2.5 hour stints at Summit last month and had no problems. We don't have A/C or a cool suit. Rob R.

Try and drive those same stints at Sebring (basically an airport) in August/September ... It sucks

Nashville last year in the heat wave was brutal (no ac/no cool suit). Sitting in the car when it died on the track between corner stations for 10 laps or so before someone noticed me was even worse.

As someone has spent the last 30 years in Vegas I get wanting AC in the race car. I do remember a couple of showroom stock guys running the AC during club race and I know of 3 Cakifornia Rally Series guys who kept the AC in their rally cars. Why not simple "run the AC" and see what happens. Take it to a track to test it simple as that.

        Tom

What would it take to have an electric driven compressor, capable of running on 12volts?

Plenty of race cars do rear radiator setup, I'd think a rear condenser would be easy enough, if they compressor could be a 12 volt electric drive.

I'd love to have A/c in my hillclimb car. The runs are short, but the staging can be very hot. I'd turn it off for the run if I had too. I don't do well with heat.

No idea how well this works, but it's simple enough. Use frozen bottles instead of loose ice. Bolt it down and go. http://www.kooleraire.com/

Also wonder if you could use an isolated heater core on a closed loop. Thinking water pump pushing coolant through a heater core submerged in an cooler ice bath, pushing to another heater core outside the cooler with the fan pushing air through it to cool you.

This was on day 4 of the Babe Rally in 2012. AC was broken so I removed the vents and filled the evaporator with ice then turned the blower on. When the ice melted the water went out through the evaporator drain. It wasn't the most efficient system but it was better then having the windows open. Downside was the passenger had to shovel ice into the dash like an old coal steam engine.

Aren't there some 12V AC systems for semi trucks, so they don't have to let their engine idle to keep the cabin cool? No idea on the price though.

I'm in the same boat as Toyman, I don't do hot real well. I run a cool shirt for hot events, that thing was fantastic at LeMons. I have also used it at hot AX events, people laughed at first but man it was nice to feel the ol' brain staying on line when it was +100 deg in the car.

My grumble about an A/C system which runs off the engine is when the engine stalls no A/C. So as one poster mentioned you sit in a hot car simmering in your own juices waiting for a tow. With a cool shirt if you have 12V you have cool. Also A/C needs an enclosed cabin to be truly effective, when you are stripping everything out of a car to make it light it doesn't make much sense to leave ~50 pounds of A/C stuff and then another ~50 pounds of glass. The cooler etc for a cool shirt is maybe 35 pounds when full of ice.

sachilles wrote: What would it take to have an electric driven compressor, capable of running on 12volts?

The compressor - even modern high efficiency versions - just needs too much HP. It would still end up being a load on the engine, except it would get pulled through some gigantic alternator. A 12V motor large enough to power an A/C compressor would drain the battery in short order.

Keep in mind, while car A/C systems generally don't have to cool a large space compared to say a house, they do have too cool at a much wider Delta-T than a typical house system that is recirculating already cooled air. This is actually a case where the aftermarket versions may be better for a race car since those are almost always 100% re-circulating systems (no fresh air option). Also keep in mind a car has much worse thermal insulation than a house and the cabin has a lot of non-insulating glass... Ever notice how quickly your car interior will heat up (or cool down in the Winter) once the engine driven HVAC system turns off?

I'm not 100% sure, but I believe OTR truck A/C systems work off either a dedicated diesel powered compressor (refrigerated trailers are like this) or a simple diesel generator and 120V similar to RV roof units.