Racing, moving to the next level Options

[Randal]

OK, all you big time racers out there, what is the correct procedure to purge air out of a tire before filling it with nitrogen?

The reason I ask is that any moisture mixed with nitrogen will create nitric acid, or some such vile stuff, if I remember correctly.

What about using air tools? Looks like a job for rubber gloves.

[SirAndy]

Your a smart guy Andy, but I just wonder if racing teams would really be going to all that trouble if it wasn't worthwhile.

don't underestimate "the power of suggestion" ! (IMG:style_emoticons/default/biggrin.gif)

but you're right. what do i know. (IMG:style_emoticons/default/confused24.gif)
i don't even have race tires, nor have i ever driven a real race car on the track. i'm sure those guys know what they're doing.

don't listen to me, i'm just babeling because it's sooo boring here at work,
Andy

[groot]

Carrol Smith recommends using a shop vac and some duct tape as a purging device. Remove the valve core and tape the hose to the valve stem and suck.....

[Randal]

Thanks groot.

Who is Carol Smith?

But I like the idea.

[thesey914]

why not use helium (or hydrogen!) because it would be lighter? (I'm not saying you should, just seeing what the response will be (IMG:style_emoticons/default/wink.gif) ).

Erm..... i reckon if you asked it would go down like the Hindenburg

[machina]

Unless I missed the boat, all you guys missed the boat....

The nitrogen tanks run the jacks in the cars. The jacks require something like 300 psi to operate so compressed air is not an option.

My buddy had a cup car with built in jacks and he had all the crap with nitrogen tanks, regulators, etc.

he used the nitrogen in the tires just because he had it around to work the jacks.

if you think having nitrogen in your tires is going to get you by your next toughest competitor keep dreaming. whatever makes you happy.

dr

[brant]

dr,

I'm willing to acknowledge that people have a right to their own opinions...

but there are a lot of racers that would disagree with you...

yes the tanks can and do run equiptment...
but try running a double stint or an enduro and dealing with the handling difference caused by tire pressures...

A track tire (non slick) will change as much as 10psi from the beginning of a session to the end...
thats a lot.. the car handles EXTREMELY different..

have you ever noticed that a race crew might make a 1lb change in tire pressure? They are not making a 10lb change, just a 1lb change.....

I really don't think its all bunk..
I don't think SCCA runnoffs competitors are uneducated, or using gimmicks in their cars...
ie: I haven't seen a lot of "turbo tornado" (registered trademark) installs on true race cars...

I'm not expressing myself very eloquently.. but this is what I do know... I have often run a 2driver car. Its not fun starting a race with your tires squirly and off by 10psi.. I'll try nitrogen (and I strongly believe what I've been told by credible racers who are friends) that there is some benefit to it..... and I actually do believe that I can pick up a couple of tenths per a lap by having my tire pressures dialed in by more than a 10psi window...


brant

[ChrisFoley]

Andy, the word is negligible (IMG:style_emoticons/default/biggrin.gif)
Except that the difference is not negligible. It is small, but noticeable. The pressure change will be smaller as the tire heats up, compared to moisture laden compressed air.
There is no point for most guys to use nitrogen in their tires. If you are planning to have it around anyway for running air tools etc, then you might as well use it in the tires too. An air compressor requires electricity, a tank of compressed gas does not.

Oh, the biggest reason for not using helium or hydrogen is the molecules are small enough to fit through the rubber. The stuff is too expensive to constantly refill the tires.

[brant]

Chris what do you run, and what do your competitors in the run offs use?

brant

[ChrisFoley]

So far I have not budgeted for nitrogen, even though I already rent 6 tanks of gas for my business. Most SCCA club racers, even at the runoffs level don't use N2.
My slicks gain about 5-7 psi from cold to hot, depending on which corner of the car is working hardest at a particular track. Most of the pressure change is within the first 3 laps. After that I can't feel any change in handling. Anyway, most of the handling change is due to the rubber softening as it warms up. I get very good, consistent tire wear because my cambers are dialed in to my driving style, ie. smooth and fast. Also I use a tire pyrometer to check for even temps, then adjust my cold pressures accordingly. I do my best to come in from a practice/qualifying session as fast as the traffic will allow to get accurate readings on the tires.
I don't need no stinking cool down lap. (IMG:style_emoticons/default/cool_shades.gif)

Oh, and I set my pressures with less than 1/4 psi increments sometimes.

[brant]

Oh gosh I'm an idiot.. I forgot you were on slicks..
b

[Randal]

if you think having nitrogen in your tires is going to get you by your next toughest competitor keep dreaming. whatever makes you happy.

I don't know about anyone else, but thinking about and doing stuff to your race car, trailer or tow vehicle is just plain fun... Also a learning experience.

Like most of us if I wasn't doing this then I'd be totally involved in something else.

BTW being competitive is important - and it makes me really happy when my car and more importantly I drive effectively at an event. But I do know the difference between using nitrogen in my tires and feeling uncomfortable using my new Renn shifter and hitting the rev limiter twice in a course. One might make a tenth of a second difference; the other seconds.

And by the way Brad, thanks for the advice (“finesse Randy!”) on using the shifter. Can’t wait until WCC.

[ChrisFoley]

Oh gosh I'm an idiot.. I forgot you were on slicks..
b

I wouldn't say that.

Slicks or DOT tires - it makes no big difference.

I used to race on DOT tires, and I don't think I ever saw 10 psi increases. The pressure settings were higher though.
I set pressures between 18 and 19 psi cold with the Hoosier slicks, and I used to start out with 28-30 cold using both Yoko or Hoosier DOT tires. The pressure increase was about the same.

The people who get such large pressure changes have cars with front engines, either fwd or rwd. The lack of balance of those cars causes the tires at one end of the car to work much harder. Anybody driving a 914 who sees a 10psi increase is probably abusing their tires IMO.

[brant]

Chris,
I was always told the DOT tires were a bit more dramatic in change.. Sounds like that was not your experience though....

I think I'm experiencing extreme temps due to abuse for 2 reasons really...

1) its a 2 driver car and the sessions are often back to back with no time for any cool down.. the car is literally pulled onto the grid and then back on the track as soon as the drive change can be completed..
2) its a locked diff car. So there is some pretty extreme rear wear going on, with a lot of tire sliding..

brant