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Author Topic:   Fill tires with air, Nitrogen or CO2 ?
BrianW
Dirt Freak

Total posts: 385
posted August 11, 2004 01:48 PM  
I'm having problems with controlling the tire pressures during the feature race, the car comes in about 2 laps into the feature, then about lap 5-6 it starts getting real loose on exit - checking tire pressure I've seen as much as 4 PSI increase on the RR tire and 2.5-3 PSI on the LR.

I've been told to fill the tires with Nitrogen and/or C02 as it won't expand as fast as 'regular air' from a compressor.... Is it worth the $200 to get a tank and regulator setup just to fill the tires???

mod70
unregistered Total posts: 385
posted August 11, 2004 02:19 PM           send a private message to BrianW   Edit/Delete Message   Reply w/QuoteBBBBBB
Get a pair of bleader valves for the rear tires. You can set them for any pressure between 5 - 50 psi and they will hold it. It's alot cheaper than extra bottles or driers for your compressor. I like the Longachre type, about $15 to $20 each, and you can take them off a bent rim and put them on a new one. They require a 1/8 NPT tap hole.

BrianW
Dirt Freak

Total posts: 385
posted August 11, 2004 03:48 PM  
I've heard the horror stories about the bleeder valves, leaking, don't close right, etc... That's what the others justified the recomendation to run a dry gas in the tires came from... Have you had any problems with running them?

racer17j
Dirt Forum Champ
Total posts: 5390
posted August 11, 2004 04:25 PM  
pure co2 vs pure nitrogen will expand the same, the reason a dry ice makes so mcuh co2 is that it is tryingto get up to room temp so to balance the equation it raises pressure. if you had co2 at room temp and heated it to 100deg c and did the same to nitrogen it will have the same pressure.
i would recomend nitrogen then get an air regulator and use the nitrogen for air at the track for tools.

mod70
unregistered Total posts: 1875
posted August 11, 2004 05:50 PM           send a private message to zeroracing   Edit/Delete Message   Reply w/QuoteBBBBBB
I have not had any problems with the bleeder vavles. The only reason I can think of people saying they leak (other than that's basicaly what they are designed to do!) is that as your tire cools off after a run, the tire pressure will drop below what you have them set at, but that's just due to the cooling air in the tire. If you're really concerned, just scillicone(sp?) them in.

racer17j
Dirt Forum Champ
Total posts: 5390
posted August 11, 2004 06:20 PM  
quote:
Originally posted by BrianW:
I'm having problems with controlling the tire pressures during the feature race, the car comes in about 2 laps into the feature, then about lap 5-6 it starts getting real loose on exit - checking tire pressure I've seen as much as 4 PSI increase on the RR tire and 2.5-3 PSI on the LR.

I've been told to fill the tires with Nitrogen and/or C02 as it won't expand as fast as 'regular air' from a compressor.... Is it worth the $200 to get a tank and regulator setup just to fill the tires???


Brian,
Go to your local commercial tire dealer and ask for a box of Tire Life. The box comes with 4 bags of a liquid they use in semi tires. Just poke a hole in the bag and drop it in. It eliminates up tp 40% of your tire heat and keeps the wheels clean.

zeroracing
Dirt Forum Champ
Total posts: 1875
posted August 11, 2004 08:03 PM  
i know dry ice is solid but it is turning to a gas, a gas takes up more space than a solid.
the dry ice bomb works because, the gas takes up more area and as it becomes a gas the gas heats up and to balance PV=nrt the p goes up to comepesate for the t going up. until it explodes then the v increases very quickly.
pv=nrt does not take into consideration the gas being used, so all gasses work the same as long as they dont have water vapor in them. the reason for the sharp increase in pressure with regular air is the water in it.
i have never seen the tire life stuff, and as far as bleeder what if a piece dust gets in thier and clogs it before it opens, or after, then it will not work or it will stay on and drainthe tire.

badasi1tob
Dirt Roller

Total posts: 21
posted August 12, 2004 09:09 PM  
Ive been told that the bleeders will only let off air while stopped or at slow speeds. At race speeds the centrifugal force is much greater that the little spring that is compressed to release the air when the pressure builds. Sounds logical anyone else hear this?

FearDaPierce 35
Dirt Roller

Total posts: 22
posted August 15, 2004 09:51 AM  
We have ran the bleeders for around 8 yrs and have had one failure and that was the bleeders we were running at the time didnt have a screen on them and a piece of dirt got in the bleeder and wouldnt let it close.Car comes off the track with the same pressure it had when it went out. We to run the longachre bleeders with the screen on them. Should have no problems

dirtywrench13
Dirt Freak

Total posts: 324
posted August 17, 2004 03:28 PM  
THROW THE MUD PLUG IN THE TRAILER FOR A NIGHT AND SEE WHAT YOU THINK.

FearDaPierce 35
Dirt Roller

Total posts: 22
posted August 17, 2004 05:40 PM  
WHY WOULD YA WANNA DO THAT?

dirtywrench13
Dirt Freak

Total posts: 324
posted August 18, 2004 01:12 PM  
HELPS PREVENT HEAT BUILDUP,TRY IT FOR THE HEAT RACE!

hamandeggerMage
Dirt Newbie

Total posts: 1
posted August 18, 2004 07:24 PM  
We've been running the bleeder valves for a long time and have had ZERO problems with them.

We tried nitrogen for awhile and must not have been doing it right because the tire pressures would always come in a lot higher than they went out. 5 pounds or so higher.

I think we are the only modified at our local track running the bleeders, but like I said, no problems at all. They do exactly what they are supposed to do.

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