Got back from my first track day about an hour ago. Quite fun, eh?

It's a friendly group. I finished 3rd outta 4 cars in GS. My times were something like 44.1, 43 + 3 cones, 45, 42 + 2, 43 + 1, 44 + 1? Can't remember offhand, but I think that my first run turned out to be my fastest, and I only had two clean runs.

Took three fun runs afterwards, and I got a cone or two with each of them too, but I think they were quite a bit quicker. For comparison, there was a kart that ran 35 something, and then a lot of the established guys running 37-39.

So, what can I take away from this? Apparently I'm not afraid of cones. The stinkers jump right out at 'cha.

The first run was just my warm-up. First track day ever, I took it easy and clean. Thought I could improve on it, but apparently all that talk about smooth and clean driving is true. I kept buggering the tight curve in the middle of the course. First two laps were with DSC, the rest were without. My slowest run, the third, was the first w/o DSC, and I think I sorta just plowed through the course. Bringing me to the big question / complaint.

What PSI to put these silly OEM Dunlop runflats at?? I went with 38 up front, 34 in back, warm. And the thing was ploooowing. Figure I need to burn up these runflats before winter, and there are three more autox events with this club, so I need all the advice I can get.

What I'm thinking is.. Figure out my tire pressure. Remember all of the proper driving bits & pieces (my hands were all over the steering wheel, I wasn't looking ahead far enough a lot of the time, tighten the lines a bit), and get faster. I wasn't steadily going fast enough, I'm still not sure what the car's limits are, at 100% handling. My lines were PRETTY good, all things considered, IMHO. Just a few inches farther away from the cones (I only nailed one or two, the rest were sideswiped ).

Recommendations people? All the help I can get will be appreciated.

Oh, last thing regarding cooling. I was using AC, full on when idling, lower (or off) while running. Kept it running inbetween runs, let it idle a bit before and after. Better ways to keep it cool?

 

i was told to run the fronts heavier on pressure too... but it seems even mine with h-sport competition sway bar set at the middle im STILL plowing! what makes me even more confused is that people tell me to run higher in the BACK! which makes me wonder even more, which is the right way to work pressure so that you get maximum rotation?

 

kyriian,
What tires are you using? Have you had an alignment done on your car?

 

Recommendations people? All the help I can get will be appreciated.

Most beginners tend to overdrive the course and end up plowing thru the corners. "Slow in, fast out" will help you stay in control.
It takes lots of seat time to get this right, anyone can nail the gas pedal to the floor, but it really takes time to learn when to brake.

Hope that helps.

 

i run 2 different, i run v710s in 215/40-16 if im at the higher levels, at club level i use street Kumho ECSTA SPT 215/45-17, and today running 42f, 38r, and seems that i still need the front a bit lower..

as for my v710.... ive ran 38 all around before, but im trying to get rear biased.. as per some of the guys here who run same size...

 

with the 710's
asphalt 45f/55r
concrete 45f/60r
I haven't run those street tires so I don't have a clue. If the sidewalls flex a lot and you are getting roll over I would up the front pressures a bit more. On the rears I would up the pressures until the rear gets tail happy and then back it down a few psi.

 

Yeah. . . I'm not sure why you've been told to run less pressure in the rear on a FWD.

I run (both on V710s and my Hankook playtires) about a 5-8psi more in the rear.

More pressure in the back tires will help offset the tendency to understeer/plow. Of course, you go into a corner hot enough and you can make anything understeer.

Sounds like you just need seat time. You have the right ideas: look ahead, etc.

How many course walks did you do?

 

I know! That's what makes sense! But everywhere I look, places are saying to run more up front. Whether a bunch of people at the track (nobody flinched when they heard the front-bias I was doing), to things like the 'novice handbook' that's on tirerack ("...and fill your tires to approximately 45psi-Front/35psi-Rear for a front-wheel-drive car").

Anyways, will reverse next time. And ya, I just need moooore time. Someone was being lazy and wasn't announcing the times for the fun laps, so they weren't real useful this time. Three weeks till the next event with this group, and I might always start looking around at neighboring places for some additional time.

I walked the course three times, twice with friends and once with an instructor who was walking all the nubs.

 

You can reduce rear grip (induce more oversteer) by either raising or lowering rear tire pressures. It is a matter of preference.

For example, with my setup I run 37F, 33R with Avon Rs. This combination breaks away neutrally in steady state sweepers. If I increase the bias more towards the front (raise front pressure or reduce rear), I'll get more oversteer. I could also induce more oversteer by raising the rear pressure to something close to or greater than the front pressures. Raising them just a bit from my nominal settings will increase understeer. You just have to keep raising them to transition to oversteer. Different tires, or different car setups, will result in different tire pressure numbers but the basic behavior remains the same.

Take your pick.

Scott
90SM

 

I run my 225/50/16 Avon's @ 38f/33r. I ran Hoosier Rs04's @ 50f/40r on asphalt and 57f/45r on concrete. The end result is all the same, giving the car less grip in the rear to aid in rotation and decrease push.

 

But why does decreasing pressure in the rear create less grip? And what about the rears flexing then, going lower?

 

less PSI in the tire, creates a "larger foot print" for the tread to contact the road, this means more traction. (as the tire "sqwishes" outward on the sidewalls.) This is why alot of drag cars lower their PSI in the rear tires. (assuming its a rear wheel drive car) Ive seen guys at the drag strip drop the PSI as low as 15psi. This tactic is also used at the beach, when cars drive onto the sand. They let air out of the tires to help the rubber roll over the sand and not get stuck.

For a front wheel drive car that is "plowing" you want the rearend to be stiff so it doesnt grip, but it slides, helping you turn the corner faster. I would suggest putting MORE psi in the rear tires, to make them slide, to help with the understeer.

 

This is a very common question. The answer is to understand that every tire has a "window" of maximum grip. You want to find that window with the front tires first. Let's say it's between 35-37psi. Then you can choose to under or overshoot the rear tire pressure to reduce traction and get the car to stop plowing. Most people choose to run more pressure in the rear because this is easier on the sidewalls of the tires (The sidewalls are normally the high wear area. Lower pressure if causes the sidewalls to wear more quickly due to the tire rolling over more.)

The reason people are telling you (a Novice driver) to run more pressure in your front tire, is to keep it from rolling over on to the shoulder and wearing it out quickly. They probably didn't bother teling you about the rear tires because it was your first event.

 

That "window of grip" bit has made the most sense. Great, understand now. Appreciate all the help. Guess I'll just need to bring my little portable air pump next time and play with it.

 

As I am reading tho all these answers that people are giving you and no one has told you how to run on your runflats.

I know that this will sound really bad and i am sure people are going to tell me i am wrong but i had the best result with 30f/32r for psi.
(of course if the rear is not coming around then and more air in the rear)

Please no one tell me i am dumb cause i had great success with this last year, think about the sidewalls on the runflats are strong enough to drive on so when you put more air in the tire you are taking away the little bit of tire roll that the stiff sidewalls give you. Take away a little PSI and you are getting the "hockey pucks" that you are driving on to be a little softer and get just a little more grip.

"th3118

Most beginners tend to overdrive the course and end up plowing thru the corners. "Slow in, fast out" will help you stay in control.
It takes lots of seat time to get this right, anyone can nail the gas pedal to the floor, but it really takes time to learn when to brake.

Hope that helps."


This is something that is very true and you will learn if you keep doing events.


I would say you should find a set of rims and some tires just for AUTOCROSSING then your everyday tires dont take a beating, and to go with that pending if they have an opition where you run I would run in street tire index for a year then get "R"s. A lot of the drivers here in MN including PAT WASHBURN who ran a 06 cooper S at nationals, said to learn what you can with street tire then go to "R"s. If you learn on "R"s the you will burn though them faster.

I hope that some of this helped you out.


Nic

 

At the few events i was part of, my friend told me to put chalk on the edge of the tires between runs. that way you know where the tire is contacting the road. I just adjusted the pressure so that the tip of the tread a a little chalk on it in the back, and none in the front. and when i say tip of the tire, i mean the part where the tread meets the sidewall. hop this helps at all
marco

 

+1, what he said, you be suprised how much fixing you driving will cure you understeer, I went from have what I though was a neutral car (H-sport comp on the middle hole) to a car with a strong tendancy to oversteer on the same set up just by fixing my driving, and I was 2 seconds faster (thanks Evo School )

 

Well, yesterday's autocross was very satisfying because my times are definitely getting better, placed 6th outta 28 in the novice class, that was PAX though, not sure what the raw times were. My raw time was solidly middle pack of the entire event I believe, so...

As for the tire question. The two events before this one, I ran 30/40 front/back. Until I realized that I wasn't actually getting any grip. The car wasn't understeering, it was just loosing traction. I don't know, but after playing around on the street the past week, I went in with 40/30, front/back, and it felt niiiiiiiiiice. This creates a reasonable amount of throttle-lift oversteer. Just about right for the stock runflats me-thinks.

 

Maybe I'm misreading this but thought I'd weigh in to clarify. Running Air Conditioning adds drag to your engine and adds heat to the system. The only thing you cool with A/C is your cabin. Everything else pays the price. Also the difference between A/C Max and Min on most cars is just a blower fan speed. Usually A/C compressors are either on or off, no in between.

If your car is overheating you should see it in a water temp gauge. If you want to help cool an engine you can turn any car's heater on full blast (air cooled cars need not apply ). In this case there is no drag on your engine, and the heater is essentially acting as an additional radiator to your cooling system. If an autocross course is long and you actually get the chance to heat up your car, autocrossers sometimes raise their bonnets to let some of the trapped heat out of the engine bay after a run.

But then the A/C was probably only used because you wrote this in July when you were baking in your car.

 

I don't know about the Mini....yet.....but on our '99 Miata, when you turn on the AC, it turns on a second electric fan which helps cool down the engine even faster.

That said, I think the most important to keep cool is the intake air. That means the intercooler if you're talking about a Cooper S. I've seen some people putting ice on the intercooler between runs. Just don't put it in a plastic bag as the intercooler can melt the plastic making a big mess.

 

Reason I was running the A/C was because I was under the assumption it would lower engine temps. (as per mitchman's bit.)

.
Last autox I went to I froze my nads off..

 

I wasn't aware of that trick for fast cooling. Miata and BMWs are longitudinally mounted rear-wheel drive, thus the motor driven fan facing the front facing radiator and an auxillary electric fan for overengineered redundancy while idling. The new Mini's got a conventional radiator placement but transverse mounting, so I think that the electric fan's the sole fan. I'd guess the chances are the A/C trick won't be needed.

 

Now, let's think about this: Running the AC is going to place a load on the engine because of the compressor. The operation of the AC in itself, creates some heat, so what is your net gain? If you really want to cool your engine temp, you turn on the heater, which will have a direct effect on heat exchange. Yes, it's blowing the heat all over you, but it's taking it out of the cooling system.

 

I've heard of people doing that as well, but it's not very common. (I'd never do it on a hot day!)

But the most common way to cool down the car is by spraying water on the intake tubes and the intercooler. "Icing" the intercooler between runs is also very common.

I'm going to be really busy between runs on a hot day. With the Miata, spraying all four tires between runs took up all the time. Now, in addition I have to open the hood and ice the intercooler? I'm going to be busy!

 

I guess it comes down to your experience. I've saved my '72 BWM 2002 from 125 degree heat West of Las Vegas in a jam. Fried my friend in the back seat but we gave him the option to get out and walk . I pulled the motor driven fan from that car now to maximize engine power (2002's don't use a fan clutch), so I regularly use the heater to offset the electric radiator fan when the engine bay gets heatsoaked. I learned the technique from owning British roadsters which are notorious for not having sufficient cooling for the hotter temperatures of North America.