Cal Club Autocross Forums

Marshall, have you tried the CO2 in practice? It seems like there is so little mass of CO2 that it would come to ambient temperature quickly.

Also, because the critical point of CO2 is 88 degrees F, under most conditions we deal with in autocross there's almost no heat of vaporization to chill the CO2 as it evaporates. Almost all the cooling comes from gaseous expansion according to PV=nRT, the same as you would get with nitrogen stored at the same pressure.

I'd expect you could fill the tires to just below the target pressure, then walk around a second time and adjust to exactly where you want it.

I went years just filling my air tank at gas stations and buddy houses every couple months.

A Viair is one of the two compressors I actually believe in.

Jay W

Bobby Beyer wrote: The airtank route gives me an excuse to buy an air compressor for my house, but as I am already the @sshole car guy, that may not be the wisest decision.

The Viair pumps look decent but I'm still not quite sold on them since it seems most of them have a duty cycle in the 33% range which seems like I would overheat it if I had lots of air to pump on all 4.

Jayson Woodruff wrote:I went years just filling my air tank at gas stations and buddy houses every couple months.

A Viair is one of the two compressors I actually believe in.

Jay W

Bobby Beyer wrote: The airtank route gives me an excuse to buy an air compressor for my house, but as I am already the @sshole car guy, that may not be the wisest decision.

The Viair pumps look decent but I'm still not quite sold on them since it seems most of them have a duty cycle in the 33% range which seems like I would overheat it if I had lots of air to pump on all 4.

Best place to fill the tires on the run? Costco. It's nitrogen and its a free service. Just pull up at the tire bay and tell them the pressure you want. Membership not needed.

John Stimson wrote:Marshall, have you tried the CO2 in practice? It seems like there is so little mass of CO2 that it would come to ambient temperature quickly.

Also, because the critical point of CO2 is 88 degrees F, under most conditions we deal with in autocross there's almost no heat of vaporization to chill the CO2 as it evaporates. Almost all the cooling comes from gaseous expansion according to PV=nRT, the same as you would get with nitrogen stored at the same pressure.

I'd expect you could fill the tires to just below the target pressure, then walk around a second time and adjust to exactly where you want it.

not for filling tires, but for air shifters. we could get frost on the regulator if we tried shifting a lot. I suppose if you had a bottle heater (like the sun) it would work better.

CO2 was rumored to be at least one of the gasses F1 was using to fill their tires with. Although it could be interesting if there is any moisture inside the tire to mix with the CO2 and make carbonic acid.

for autox i'm sure any of the solutions proposed are acceptable.

Marshall Grice wrote: not for filling tires, but for air shifters. we could get frost on the regulator if we tried shifting a lot. I suppose if you had a bottle heater (like the sun) it would work better.

CO2 was rumored to be at least one of the gasses F1 was using to fill their tires with. Although it could be interesting if there is any moisture inside the tire to mix with the CO2 and make carbonic acid.

for autox i'm sure any of the solutions proposed are acceptable.

Yeah, I used to paintball and before I switched to HPA, the regulators would freeze up and stop working after a long burst, pretty annoying when you're pinned down. Funny enough though I have a N2O bottle heater but I have no idea how well that would work with CO2.

I'm going to pickup and airtank and use the compressor at my work for the time being, before I decide to either get a compressor for my place or go with a little tire compressor.

Several of us over in AZ use this high volume 12V compressor available at both Amazon and Pep Boys for under $60. I've had mine for ~ 6 years.. works excellent.

http://www.amazon.com/Industries-MV50-S ... compressor

http://www.pepboys.com/product/details/9357343/00659/

Jay Balducci wrote:Several of us over in AZ use this high volume 12V compressor available at both Amazon and Pep Boys for under $60. I've had mine for ~ 6 years.. works excellent.

http://www.amazon.com/Industries-MV50-S ... compressor

http://www.pepboys.com/product/details/9357343/00659/

I mostly use nitrogen now that I'm towing and have my truck at events. But before that, this compressor was my mainstay. Works great and is fast. Not as fast as an air tank however. But, unlike and air tank, it never runs out of air.

George Schilling wrote:...Just like me, it never runs out of hot air.

Fixed that for ya', George. Happy New Year.

Bill Schenker wrote:

George Schilling wrote:...Just like me, it never runs out of hot air.

Fixed that for ya', George. Happy New Year.

Thanks Bill!