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Using Nitrogen? Please step inside...

Old 11-08-2007, 02:24 PM
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95jersey
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Default Using Nitrogen? Please step inside...

OK, so a buddy of mine got Nitrogen at his shop and told me he would fill my tires at no cost. I know they use nitrogen in many race series and would be interested in trying it at the track next year.

Now the tricky part...R compounds like Hoosier or 710's have cold and hot recommended pressures. I usually start cold around 30-31 and they get up to about 35-38 and seem to work well in that zone.

The whole purpose of Nitrogen is that it doesn't expand or contract like regular air due to heat. So you fill them up a given temp and theoretically, it should stay at that temp, heat regardless. So if you were to fill your track tires with Nitrogen, would you fill them at the HOT temp from the start (35-38)? Or the cold temp (30-32)? I am told, at most they only go up or down a 1lb in the most extreme conditions.

Just looking to see what people experience in the real world.
Old 11-08-2007, 02:29 PM
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0Randy@DRM
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You should start them about 2 maybe 3 pounds under your hot pressure. Then double check them cold vs hot. We have seen a couple pound change cold vs hot.

Randy
Old 11-08-2007, 02:34 PM
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Mojave
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Originally Posted by 95jersey
The whole purpose of Nitrogen is that it doesn't expand or contract like regular air due to heat. So you fill them up a given temp and theoretically, it should stay at that temp, heat regardless. So if you were to fill your track tires with Nitrogen, would you fill them at the HOT temp from the start (35-38)? Or the cold temp (30-32)? I am told, at most they only go up or down a 1lb in the most extreme conditions.
That isn't quite right. All gases expand when hot. Every single one. Some just do it more than others.

PV=NRT
P=pressure
V=volume
N=amount of gas (in moles)
R=Constant
T=Temp

So, the pressure will still rise with temp (but without the water and other stuff that is in the air, not as much).
Old 11-08-2007, 02:38 PM
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AU N EGL
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N2 only expands 2-3 psi max. AIR can go 8-10 psi.
Old 11-08-2007, 03:08 PM
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95jersey
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Also, it great that I can get free Nitrogen, but when I need to add some air at the track, I won't be carrying extra Nitrogen, so would mixing with air be an issue?
Old 11-08-2007, 03:22 PM
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Z Fast
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Originally Posted by 95jersey
Also, it great that I can get free Nitrogen, but when I need to add some air at the track, I won't be carrying extra Nitrogen, so would mixing with air be an issue?
You would only be adding a small volume of air, and won't change things. Realize, even when you fill with Nitrogen, there is still a lot of air in the tire. In other words, they don't vacuum the tire before filling with nitrogen.
Old 11-08-2007, 03:26 PM
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Another issue is evacuating all of the normal air (water content) out of the tire. Unless you draw a vacuum on the mounted tire and maintain it until nitrogen is introduced, there will still be some normal air (water content) in the tire.

I'd expect the normal air mixed with the nitrogen would decrease the benefit of the nitrogen.
Old 11-08-2007, 03:45 PM
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AU N EGL
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Most ppl let all the air out of the tire, then fill with N2. Doing this three times each wheel should get most of the AIR out
Old 11-08-2007, 04:46 PM
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RossJackM
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Default Nitrogen in tires

Air is 79% Nitrogen! If there is any difference, it would be in moisture content. Try putting a dryer on the air you use for inflating. The other advantage is not having the 19-20 % Oxygen in the tire? I suppose that this will help with any oxidation inside the tire at high temperatures!
Old 11-08-2007, 05:10 PM
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Ben Diss
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Originally Posted by Falcon
Another issue is evacuating all of the normal air (water content) out of the tire. Unless you draw a vacuum on the mounted tire and maintain it until nitrogen is introduced, there will still be some normal air (water content) in the tire.

I'd expect the normal air mixed with the nitrogen would decrease the benefit of the nitrogen.
They should be evacuating the ambient air from the tire. This is how mine were done:

http://forums.corvetteforum.com/show....php?t=1849184
Old 11-08-2007, 05:13 PM
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I take my race car to tire discounters. Everything's included including allignment! Plus free nitrogen inflation! These guys really know their stuff!
Old 11-08-2007, 05:13 PM
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Originally Posted by AU N EGL
Most ppl let all the air out of the tire, then fill with N2. Doing this three times each wheel should get most of the AIR out
That was my job as a kid. Fill and release, fill and release, fill and release, then fill and gauge. It wasn't so bad besides the when we ran 6 cars, with at least three sets of tires for the weekend.

Randy
Old 11-08-2007, 05:15 PM
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Originally Posted by 95jersey
Also, it great that I can get free Nitrogen, but when I need to add some air at the track, I won't be carrying extra Nitrogen, so would mixing with air be an issue?
Fill a small tank with the Nitrogen and bring to the track.

Randy
Old 11-08-2007, 05:52 PM
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Originally Posted by Randy@DRM
Fill a small tank with the Nitrogen and bring to the track.

Randy
You can buy a pressure regulator and hose setup for your garage at home and fill your own tires with N2 at will. You can get the N2 from a gas supplier and as Randy has said, fill up your track air tank for adjustments.
Old 11-08-2007, 06:08 PM
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Originally Posted by Tintin
You can buy a pressure regulator and hose setup for your garage at home and fill your own tires with N2 at will. You can get the N2 from a gas supplier and as Randy has said, fill up your track air tank for adjustments.
Running a regulator setup on the fly is kinda a pain. D.O.T will not let you drive a car or truck or trailer with the regulator on, you must have the saftey cap on during transport.

I was thinking a small air tank that you can buy at the auto parts store.

Randy
Old 11-08-2007, 06:30 PM
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Originally Posted by Randy@DRM
That was my job as a kid. Fill and release, fill and release, fill and release, then fill and gauge. It wasn't so bad besides the when we ran 6 cars, with at least three sets of tires for the weekend.

Randy
You were so abused as a child!
I bet they wouldn't even let you huff it either!!!
Old 11-08-2007, 06:31 PM
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Originally Posted by Randy@DRM
That was my job as a kid. Fill and release, fill and release, fill and release, then fill and gauge. It wasn't so bad besides the when we ran 6 cars, with at least three sets of tires for the weekend.

Randy
One of my first jobs on the race cars too

The main advantage is to remove as much moisture content from inside the tires as you can. The change in water vapor can affect pressures on the cars, and if you are keeping track of your pressures at different tracks under different conditions this can better give you an idea of what to set the tires for given a certain air and track temp.

What you are looking for is consistency in your testing methods and measurements.

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To Using Nitrogen? Please step inside...

Old 11-08-2007, 06:57 PM
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I use it as much for convienence as much as the technical advantages. I had to buy a tank and regulator anyway for the Penske shocks, so I put it on a Wal-mart dolly and now I use it for everything. It is only about $20 to fill it and it lasts me about 6 months. It is easy to take to the track, and I find that even when my wife's Caddy or my tractor needs air in the tires, it is easier to take the tank to the car or tractor then dragging the long hose from the compresor.
Old 11-08-2007, 08:16 PM
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How much does it cost to put a dryer on your regular air compressor?
Old 11-08-2007, 09:42 PM
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Originally Posted by Randy@DRM
That was my job as a kid. Fill and release, fill and release, fill and release, then fill and gauge. It wasn't so bad besides the when we ran 6 cars, with at least three sets of tires for the weekend.

Randy
CPS is what they call it in NY, Child Protectives Services

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