High altitude PAX

[100_Percent_Juice]

Or maybe he doesnt have his hands at 10 and 2?

[MikeK]

Originally Posted by SFVette

<snip>

Welcome to the wrong guy won pax club. We have donuts and coffee!

[Dean]

If that is the car I think it is, I would be surprised if it was correctable. If there was a way to get more front end grip on that car, they would have found it.

[MattR]

The engines don't care what altitude they are run at - it only cares what the air pressure, temperature and humidity is. Sea level at 30.15 inches baro is exactly the same as 4500 ft at 30.15inches, (Which is exactly where the Barometer sits for Reno and Oakland, Ca today!) as far as the engine is concerned. . To me, an altitude adjustment is just as necessary as a temperature and humidity adjustment

[AtomicLabMonkey]

Originally Posted by Dean

If that is the car I think it is, I would be surprised if it was correctable. If there was a way to get more front end grip on that car, they would have found it.

You'd be surprised... I've seen sponsored, factory supported race teams in a touring road race series doing some stupid shit before, and that's just an auto-x car.

[sperry]

Originally Posted by AtomicLabMonkey

You'd be surprised... I've seen sponsored, factory supported race teams in a touring road race series doing some stupid shit before, and that's just an auto-x car.

Actually, I think the autocross guys tend to get things right more often than the road race guys... in autocross every .001s counts and you can't make up anything by driving a defensive line. In road race you can get away with more issues than you can at a national level in autocross.

That car looks like it's at the top level of autocross... think of it as an F1 car. I'd expect to see more dumb-ass stuff at lower levels of road race than at the top level of autocross. Sure, it's just autocross, but those folks are the best in the world at it.

[AtomicLabMonkey]

Originally Posted by sperry

Actually, I think the autocross guys tend to get things right more often than the road race guys... in autocross every .001s counts and you can't make up anything by driving a defensive line. In road race you can get away with more issues than you can at a national level in autocross.

That car looks like it's at the top level of autocross... think of it as an F1 car. I'd expect to see more dumb-ass stuff at lower levels of road race than at the top level of autocross. Sure, it's just autocross, but those folks are the best in the world at it.

Whether or not that assesment is right, his suspension is definitely not working right. And I'm sure it is at the top of auto-x; from that small pic it looks like Vic Sias' car. I used to get spanked by him at AAX events in SM.

[sperry]

Originally Posted by AtomicLabMonkey

Whether or not that assesment is right, his suspension is definitely not working right. And I'm sure it is at the top of auto-x; from that small pic it looks like Vic Sias' car. I used to get spanked by him at AAX events in SM.

My bet is that with the range of adjustment his suspension gives him, he probably can't get the car to keep that tire down without going slower. At autocross speeds, sometimes lifting a tire doesn't hurt you since you're basically going around the corner in a controlled spin anyway... more tire isn't really going to help, in fact it could be construed as "drag". I know that's what the FWD guys think... they want to lift a rear tire 'cause it lets the car turn!

[Dean]

In a powerful car, keeping the driving wheels, and the outside front down are the key. if that means the inside front or rear lifts, so be it.

Not positive, but I would bet the weight transfer rates side to side in autocross are probably the highest of any automobile motorsport except maybe F1. Not many suspensions can handle that as well as being flexible enought to keep the tires in contact on the bumpy stuff.

And don't think that wing is bling. If it isn't functional at autocross speeds, I gurantee it wouldn't be there.

[dknv]

Originally Posted by AtomicLabMonkey

from that small pic it looks like Vic Sias' car. I used to get spanked by him at AAX events in SM.

The file has 'sias' in the filename, and Vic did run 199 SM at nationals. Lifting a wheel may have meant he didn't get the car dialed in for that surface (if the pic is from nationals, the slipperly slope course ).

[AtomicLabMonkey]

Originally Posted by Dean

In a powerful car, keeping the driving wheels, and the outside front down are the key. if that means the inside front or rear lifts, so be it.

That is completely flawed thinking, Dean. The outside front will always be planted in a turn, no matter what you do. The key to maximizing front-end grip is getting the most work out of *both* tires, not just the outside one. A pair of tires will produce their highest combined lateral force when they are near equally loaded. I have driven powerful RWD cars and believe me, they can understeer too. You can't just forget about making the front end work right cause "they gots mad p0wah!!".

[Dean]

Originally Posted by AtomicLabMonkey

That is completely flawed thinking, Dean. The outside front will always be planted in a turn, no matter what you do. The key to maximizing front-end grip is getting the most work out of *both* tires, not just the outside one. A pair of tires will produce their highest combined lateral force when they are near equally loaded. I have driven powerful RWD cars and believe me, they can understeer too. You can't just forget about making the front end work right cause "they gots mad p0wah!!".

I am not disagreeing with you, it would be nice to have all 4 wheels on the ground, but as I mentioned in the paragraph you didn't quote, the transitional forces in autocross are extreme, and having a suspension that will absorb those forces while still permitting the individual corners to conform to the contours of the course within the confines of the rules for that class is not always possible.

Even in SM, the class we are discussing, you can't change the basic geometry of the suspension. Anti-sway bars, shocks, springs and camber/caster adjustment of some form is all you get.

So the compromise in autocross is what setup gives the fastest raw times for the combination of the car and the driver's driving style, period. Unlike other motor sports where tire wear from countless sources, fuel mileage, and similar things just don't matter. Camber, caster and toe can and are set to angles that would destroy tires in most any other form of motor sports. very large anti-sway bars are employed to try and manage the lateral transitional forces that would again be overkill for other types of driving. A "perfectly" setup national level autocross car can be almost undriveable at the track due to lack of high speed stability, overly responsive handling, and tendency to rotate.

Of the cars from of people on this board, my WRX may have been the closest to this configuration and it was a handful at the track, ask Scott, but it wasn't even close to the level of insanity the nationally competitive cars are at. Oh, and it lifted the inside rear at autocross, but not at the track.

[AtomicLabMonkey]

Originally Posted by Dean

I am not disagreeing with you, it would be nice to have all 4 wheels on the ground, but as I mentioned in the paragraph you didn't quote, the transitional forces in autocross are extreme, and having a suspension that will absorb those forces while still permitting the individual corners to conform to the contours of the course within the confines of the rules for that class is not always possible.

Even in SM, the class we are discussing, you can't change the basic geometry of the suspension. Anti-sway bars, shocks, springs and camber/caster adjustment of some form is all you get.

And as I was saying, changing the geometry of the suspension is not necessary to keep the tires on the ground, especially in a car like the E36 that has decent geometry to begin with. Lifting a tire is usually a roll stiffness distribution and/or damper issue (either insufficient travel or too much valving stiffness). Both of which can be dealt with inside the confines of most autocross class rules (even in SP you can change springs, shocks & swaybars as I recall). It is a correctable problem.

I know autocross presents a different dynamic load picture than track events, and I also know chassis setup is frequently a hurried compromise during any given race weekend. The simple fact remains that lifting wheels means you just haven't figured out how to dynamically balance the car correctly, and you're leaving something on the table. 3 tires cannot produce as much grip as 4. "Autocross forces are too extreme" is not a good excuse in my opinion.

[SFVette]

Originally Posted by MikeK

Welcome to the wrong guy won pax club. We have donuts and coffee!

Do we still meet at the Horsepower cafe?

Cause power is all you need to win.

[MikeK]

Originally Posted by SFVette

Do we still meet at the Horsepower cafe?

Cause power is all you need to win.

Yes, and we only use cheater tyres!

[MattR]

So who's the favorite for "wrong guy to win PAX" for 07?

[SFVette]

Originally Posted by MattR

So who's the favorite for "wrong guy to win PAX" for 07?

Sorry MattR but it has to sperry with a car that needs more attention than a wife and three kids. Thats if he runs street tires.

[sperry]

Originally Posted by SFVette

Sorry MattR but it has to sperry with a car that needs more attention than a wife and three kids. Thats if he runs street tires.

I'll never win PAX. My car is only sorted about 1/3 the time... you can't win PAX when 2/3 of the events you're lucky to scrape into the top 10.

[Kevin M]

Originally Posted by SFVette

Sorry MattR but it has to sperry with a car that needs more attention than a wife and three kids. Thats if he runs street tires.

I'm thinking Dean would have made a strong run from BSP, especially if he goes nuts with his tire combo. But since he won't be a factor, my money is on Ken Garcia if he runs the full schedule.

[Dean]

Originally Posted by AtomicLabMonkey

And as I was saying, changing the geometry of the suspension is not necessary to keep the tires on the ground, especially in a car like the E36 that has decent geometry to begin with. Lifting a tire is usually a roll stiffness distribution and/or damper issue (either insufficient travel or too much valving stiffness). Both of which can be dealt with inside the confines of most autocross class rules (even in SP you can change springs, shocks & swaybars as I recall). It is a correctable problem.

I know autocross presents a different dynamic load picture than track events, and I also know chassis setup is frequently a hurried compromise during any given race weekend. The simple fact remains that lifting wheels means you just haven't figured out how to dynamically balance the car correctly, and you're leaving something on the table. 3 tires cannot produce as much grip as 4. "Autocross forces are too extreme" is not a good excuse in my opinion.

But do you agree that setup is about compromise? If so, I submit that lifting a tire is an acceptable compromise to minimize lap times. Keeping a tire on the ground in a specific turn type is not the objective. Best performance in the parts of the course that make the biggest difference is. Keeping all 4 tires planted in a fast slalom may be more important than doing so in a tight constant radius corner. Tuning for both may be impossible. So the compromise is sacrifice performance in the later to maximize performance in the former.

Also in autocross, the car has to be as consistent as possible. You only get 3 runs, and the car has to be predictable on run 1, not after 4 practice sessions and many sessions of tweaking on a given weekend.

I have even seen AM, now XM "cars" lift inside fronts in tight corners. These are the fastest autocross vehicles made. Do you honestly believe these people wouldn't eliminate that if it was beneficial? Doing so would likely require them to compromise something else that would cost them time over a greater portion of the course.

[AtomicLabMonkey]

I submit that I am done arguing about this. I have made my point as clearly as I know how. If you think it is the fast way around a course, go on lifting wheels with bliss. I salute you.

[Dean]

Originally Posted by AtomicLabMonkey

I submit that I am done arguing about this. I have made my point as clearly as I know how. If you think it is the fast way around a course, go on lifting wheels with bliss. I salute you.

OK. But I will pose one more question.

Do you honestly beleive that the same setup that gets you through the Andretti hairpin fastest will also be the best setup to get you through the corkscrew the fastest at Laguna Seca?

If so, I wish you luck, if not, then I have made my point.

[MattR]

Originally Posted by SFVette

Sorry MattR but it has to sperry with a car that needs more attention than a wife and three kids. Thats if he runs street tires.

Well, I know it won't be me, next year will be a learning year for me....I've gotta that that Ken Garcia has a great shot from DSP, and Mike K and Scott (with a running car) are always a good choice.

[MikeK]

Originally Posted by AtomicLabMonkey

If you think it is the fast way around a course, go on lifting wheels with bliss. I salute you.

If you can lift all 4 high enough then the cones are no longer a problem.

[AtomicLabMonkey]

I hate myself for even reading this thread anymore, but for the life of me I can't stop hitting the reply button.

Originally Posted by Dean

OK. But I will pose one more question.

Do you honestly beleive that the same setup that gets you through the Andretti hairpin fastest will also be the best setup to get you through the corkscrew the fastest at Laguna Seca?

If so, I wish you luck, if not, then I have made my point.

Gosh, I sure do love having words put in my mouth. What part of

Originally Posted by me

I also know chassis setup is frequently a hurried compromise during any given race weekend.

did you not understand? Let me run through it very explicitly:

If I was for some reason responsible for setting up that car I might come to the same setup conclusions they did during the weekend, and end up merrily carrying a tire around the course in order to minimize my overall times. During that weekend.

When it was over, I would set about fixing the problem of lifting a tire, by examining the available shock travel, considering a revalve, adjusting roll stiffness, etc. - in order to fix the problem. I wouldn't sit there and come up with fatalistic excuses like

A number of RWD cars do that in tight autocross turns. Just like AWD and FWD lift the inner rear.

OK, I know it is suspension geometry not which wheels drive, but those are the symptoms.

and

I have even seen AM, now XM "cars" lift inside fronts in tight corners. These are the fastest autocross vehicles made. Do you honestly believe these people wouldn't eliminate that if it was beneficial?

in order to convince myself that the problem didn't need to be fixed.