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Discussion Starter · #1 ·
I am going to autocross for the first time this Sunday at Firebird Raceway in Phoenix. Anyone have a recommendation on tire pressure for the non LSS stock tires? Should the pressure be measured with the tires cold or hot? I expect the outside temperature to be 65 in the morning going to 80 by afternoon.

Thanks!
 

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Discussion Starter · #3 ·
No,
this will be the first time. I will give you a call about the school 12/4.
 

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There's been a number of threads on this subject, some folks are suggesting higher, a few lower. Just go with the Lotus recommended pressures. Set when cold, then check again just before you make your runs and bleed off (assuming it's warmer & the tire pressure is higher). This will be a good starting place.

Another tip - make sure you're warmed up. The ECU will not allow you to use the cam unless the engine is up to temp.

Kiyoshi

Edit: I've autoX'd on both tires. At Lotus recommended pressures there is no roll over. The factory guys run the cars all day at the recommended pressures on the track and gymkana/autoX type testing. You have to remind yourself that Lotus is a performance car company and they know how to set-up cars. I've found it best to start with their recommendations and then tune to your liking. With other cars I do the typical 2nd guess the factory, but not with a Lotus (to start). In the long run this will save you time & grief (just my MHO)...
 

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I prefer to set my tires cold to the temp I like and them progressively bleed air after each run as they warm up to keep them at my desired temp. I would start with 10 lbs higher than factory and then go up or down from there to suit your tastes.
 

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Stan and I had good luck with 26-30 or 27-31 cold on the AD07s. Having the backs 4 pounds higher seemed to really help with the oversteer.

Good luck and have fun.
 

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Kiyoshi-great comment on warming up your car. The last thing you want is to be bouncing off the rev limiter at 6200 halfway through your 1st straight. :rolleyes:

Stan dyno'd the car at different temperature levels, too, and found that if you can start your runs with your engine temperature lower, you get more HP. So between runs shut it down and/or open your trunk lid. Bringing your 2nd key really makes this easy.
 

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do not set tires hot

I agree with Stan, Kiyoshi and others when recommending tire pressures similar or only slighly higher than Lotus recommendations. This is especially true if you are just starting out with autocrossing.

I suggest you set your pressures cold. I have used both the recommended and two lbs less than recommended for autocross. I started with plus three pounds for track use and backed it off to recommended pressures for the afternoon session. I am getting roll over to the diamonds at the recommended pressures.

I do not recommend you set your tires to the recommended pressures when they are hot or to bleed down to the recommended pressures when hot. You can start at some pressure cold and try your car. Then bleed off a pound or two only, and try again. Watch the sidewall of your tire to see if you are rolling the tire over the the diamonds. If you go past, you have gone too far. If you do not reach them, you have to ask yourself if you are cornering at the limit and the tires are not rolling over or if you are still exploring the limits of the tires. If the latter, do not change the pressures but push harder.

My thoughts, your pressures may vary, practice, practice, practice...

Michael
 

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For autocrossing, I recommend setting the pressure before each run.

If you only set the pressure when the tire is "cold", then the pressure gain during each run is going to result in much different pressures on later runs compared to earlier runs. The result is that at least some of your runs are done with a poor setup. Additionally, you will not be able to experiment with the pressures, because once the tires have warmed up you lose your "cold" reference point.

By setting the pressure before each run, you know the pressure during that run to within 1-2psi. You can also adjust the pressure between runs, and be able to record the pressure and results and use the settings at later events.

Of course, if you're setting the pressure before each run, you're probably not going to use the manufacturer's recommended "cold" inflation pressure. The cold pressure plus 2-4 psi to compensate for normal heating might produce a good first guess, but you have to experiment and adjust from there.

The diamonds, or arrows, are not there to indicate the appropriate wear region. They simply indicate where to find the wear bars. Some people use them as a reference point for shoulder wear, but tires vary in how much shoulder wear they experience when inflated to achieve maximum grip/performance.

Michael is right that you shouldn't fixate on the tire pressures when you are first learning how to autocross. In fact, you should probably set them once and forget about them for the rest of the event like he said.

Michael and Kiyoshi, where have you autocrossed your cars? I haven't seen you at the SCCA or AAS events.
 

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John Stimson said:
Michael and Kiyoshi, where have you autocrossed your cars? I haven't seen you at the SCCA or AAS events.
Hi John,

It's been a bunch of years since I've competitively AutoX'd. I was pretty active 10-15 years ago with the NCSCC series (was the Prez NCSCC for a couple of years in the 80s). I competed in a Seven, but then got active in vintage and my autoX'ing time suffered.

I "Graduated" to a F/B car (sold the Seven) and then had a big shunt a few years ago. The car is still in restoration mode. In the meantime my autoX'ing never went away, just did a few events each year for fun.

Honestly, I'm a bit out of touch with the latest tires, shocks, etc, but I think the Elise will get me back out there. There's still a lot of names of folks I recognize from my previous time competeting and it would be good to re-kindle those friendships.

Kiyoshi
 

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AZRED where were you? You didn't let a little thing like a downpour dissuade you? It only rained until about 10am and the track dried quickly after that.

I was hoping to take some pictures of your red car in action. There were three Elises at the autocross. 2 ST and the Starlight Black demo from Scottsdale Lotus. Only the 2 ST cars competed.

Sign up for the autocross training day in December and I'll see you there.
 

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Discussion Starter · #12 ·
Rain Day

Yup,
Ready to leave at 6:30 am with the car packed and it was raining. I thought about the wet car, wet novice autocross and remembered why I don't golf in the rain since I moved here... Arizona always has a great day for the next try! I am confirmed for the driver’s school 12/4 and will see you there. Sorry I missed the largest gathering of Elises in Arizona, I had no idea that many had been delivered. Maybe we should start some weekend runs. I did drop by the British Car show at the Pavilions and the Porsche Car Club gathering in Carefree, I think the Elise drew more attention than anything on display from the crowds. By the way, I saw a ST Elise on Carefree Hwy Sat., hope I see him on my nightly run past Bartlet Lake up Seven Springs Rd.

AZRED
 
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