Data acquisition

[John Brown]

Wheelman_13,

I get throttle from the OBDII port on the car via Bluetooth. Brake would be nice, but that would require a professional data logging system at a much higher price point. I'm looking for seconds, not tenths or hundredths. At #12, I estimate I was about 4 seconds slower than the car capability.

hmmmm.. that puts your car at 11th place Pax.. and 6th place DAX. not real impressive for a car prepped better than JY's 197.

[dewittpayne]

Wheelman_13,

I get throttle from the OBDII port on the car via Bluetooth. Brake would be nice, but that would require a professional data logging system at a much higher price point. I'm looking for seconds, not tenths or hundredths. At #12, I estimate I was about 4 seconds slower than the car capability.

hmmmm.. that puts your car at 11th place Pax.. and 6th place DAX. not real impressive for a car prepped better than JY's 197.

Oh, puhleeze. Apples and oranges. That's capable of on that day on the street tires that were mounted on the car, not Hoosiers, on which the DAX and PAX indexes you're using are based. The DAX for F Street, if I read the graph correctly is something like 0.78 which would have put me in first by more than 1 second if I had been four seconds quicker. Even I think that's too low. An index of 0.80, however and a 4 second quicker time would have put me in second overall. That same PAX would have put Mark P in first, barely, in my car at event #9. I think that's quite reasonable. Really.

Hoosiers would be good for another second or two at the cost of a higher index.

[John Brown]

Wheelman_13,

I get throttle from the OBDII port on the car via Bluetooth. Brake would be nice, but that would require a professional data logging system at a much higher price point. I'm looking for seconds, not tenths or hundredths. At #12, I estimate I was about 4 seconds slower than the car capability.

hmmmm.. that puts your car at 11th place Pax.. and 6th place DAX. not real impressive for a car prepped better than JY's 197.

Oh, puhleeze. Apples and oranges. That's capable of on that day on the street tires that were mounted on the car, not Hoosiers, on which the DAX and PAX indexes you're using are based. The DAX for F Street, if I read the graph correctly is something like 0.78 which would have put me in first by more than 1 second if I had been four seconds quicker. Even I think that's too low. An index of 0.80, however and a 4 second quicker time would have put me in second overall. That same PAX would have put Mark P in first, barely, in my car at event #9. I think that's quite reasonable. Really.

Hoosiers would be good for another second or two at the cost of a higher index.

Lordy... how many versions of that I have heard!

but, now you know you just need to go 4 seconds faster.

[jcox07]

Hoosiers on heavier cars with the right width will do better for those cars than hoosiers on lighter cars. My car will get more time than say a honda or miata, I think and I would love to see what rife and JB could do with hoosiers and on the same course and then put on the toyos and see what time they would get with those. I would think it wouldn't be as much as my car or Richard's car. I have said it before we have a class for every car and if you want to run pro prep your car and earn it, otherwise just go to nascar and others that have cattered to the new crowd just to see that crowd leave after a couple years and your core racers are gone as well. I will be in pro next year for the first time and yes I want to win, but that is the key I want to win it not have it given to me. It is good to get new people in the sport, but it needs to be done in the way that core racers did and paved the way for us new racers. I can look back and say that my car is prepped as good as it can be for esp and I have gotten better, now it is time to see what I and my car can do at the local events as well as the tour events

[scottgib]

"Hoosiers on heavier cars with the right width will do better for those cars than Hoosiers on lighter cars."

Not so sure about that.

JY, you ran against a Mini S three times this year that had old worn Hoosiers, approximately 180 hp, and modified suspension. The Mini came out better all three times. Now your car has been improved since the last head to head run, and the results would likely be different now. New Hoosiers would help the Mini, but your driving looks to have improved.

Toyo's vs R's is a different story on any car that they fit.

[MARKP]

Toyos shouldn't enter into the equation. They are cheater tires that wear out faster than Hoosiers.

Sent from the Galaxy

[jcox07]

Yea my driving has gotten a lot better, but the car has been prepped down to esp and has made it better due to taking about 100 hp out of it.

[John Brown]

Toyos shouldn't enter into the equation. They are cheater tires , faster than Hoosiers.

Sent from the Galaxy

fixd that fer ya!

[MARKP]

Toyos shouldn't enter into the equation. They are cheater tires , faster than Hoosiers.

Sent from the Galaxy

fixd that fer ya!

Exactly! Street should get hammered on DAXPAXRRAX because of those tires!

Sent from the Galaxy

[integra55]

Toyos shouldn't enter into the equation. They are cheater tires that wear out faster than Hoosiers.

Sent from the Galaxy

wear faster than Ho-Ho's ? I put these on after the 24hr Labor Day '12 … there is still measurable tread on them … however many a-x's to finish up '12 and between 20 - 25 in '13 … plus 3 sessions on track at CMP (rain sessions)

I'm just waiting for the R2R to hit the market

[MARKP]

Toyos shouldn't enter into the equation. They are cheater tires that wear out faster than Hoosiers.

Sent from the Galaxy

wear faster than Ho-Ho's ? I put these on after the 24hr Labor Day '12 … there is still measurable tread on them … however many a-x's to finish up '12 and between 20 - 25 in '13 … plus 3 sessions on track at CMP (rain sessions)

I'm just waiting for the R2R to hit the market

You know, I heard on teh interwebz that was a problem with them Yotos. They figured out they was so sticky that the asphalt was coming off and stickin to teh tirez.

Sent from the Galaxy

[dewittpayne]

Data acquisition would be good for quantifying any difference between Hoosiers and street tires. I'd like to see things like peak lateral and average total acceleration over short course. Generally all we get in tests, when there are any, is a few times, and maybe a skid pad reading for one brand of car. I don't see why we can't get a lot more engineering data. It's not like they would be giving away secrets to other manufacturers, who probably already have the data on their competitors tires.

30meter radius circle, circumference 188.5m
0.9 g = 16.27 m/s = 11.58 s/lap
1.0 g = 17.16 m/s = 10.99 s
1.1 g = 17.99 m/s = 10.48 s

17.99 m/s = 63.6 kph = 39.5 mph

Obviously that's oversimplification. Peak transient lateral g is probably higher than steady state on a skid pad. It doesn't tell you anything about braking and acceleration, but it does show that a little bit of extra grip, or better cornering technique so you don't fall off the far side of the slip angle curve, can go a long way. Terminal understeer hurts in two ways, your lateral g is lower and you're traveling further.

30.3 meter radius circle, circumference 190.4m

0.9 g = 16.36 m/s = 11.64 s/lap

So too wide by a foot and a drop from 1.0 to 0.9 g costs 0.65 seconds.

And knowing this in your head is not the same as being able to do it under pressure.

I'm also not sure why the lower stock classes are supposed to benefit less from stickier tires unless their suspension geometry is truly atrocious or they can't get enough rubber under the fender. The rule of thumb is that the effective coefficient of friction of a tire decreases with load. A stickier tire has higher rolling resistance, but I don't see that being a problem at autocross speeds.

[John Brown]

Data acquisition would be good for quantifying any difference between Hoosiers and street tires. I'd like to see things like peak lateral and average total acceleration over short course. Generally all we get in tests, when there are any, is a few times, and maybe a skid pad reading for one brand of car. I don't see why we can't get a lot more engineering data. It's not like they would be giving away secrets to other manufacturers, who probably already have the data on their competitors tires.

30meter radius circle, circumference 188.5m
0.9 g = 16.27 m/s = 11.58 s/lap
1.0 g = 17.16 m/s = 10.99 s
1.1 g = 17.99 m/s = 10.48 s

17.99 m/s = 63.6 kph = 39.5 mph

Obviously that's oversimplification. Peak transient lateral g is probably higher than steady state on a skid pad. It doesn't tell you anything about braking and acceleration, but it does show that a little bit of extra grip, or better cornering technique so you don't fall off the far side of the slip angle curve, can go a long way. Terminal understeer hurts in two ways, your lateral g is lower and you're traveling further.

30.3 meter radius circle, circumference 190.4m

0.9 g = 16.36 m/s = 11.64 s/lap

So too wide by a foot and a drop from 1.0 to 0.9 g costs 0.65 seconds.

And knowing this in your head is not the same as being able to do it under pressure.

I'm also not sure why the lower stock classes are supposed to benefit less from stickier tires unless their suspension geometry is truly atrocious or they can't get enough rubber under the fender. The rule of thumb is that the effective coefficient of friction of a tire decreases with load. A stickier tire has higher rolling resistance, but I don't see that being a problem at autocross speeds.

Dewhitt... Im not sure whos thumb your under.. but if you had ever road raced.. the seat of your pants dyno-data machine would tell you that's not true. You use the grade of the course to your advantage by cornering harder and braking harder when the force is increased.. and it only takes one time to figure out..a falling pressure or pavement leaving the tire to witness decrease in grip.
all this bs numbers and competitive theory is meaningless. Unless you are an engineer for a F1 team and can really use atmosphere to your advantage.
When centrifugal over comes weight and gravity is when you lose grip........ simple.

[steverife]

I don't give a crap about Hoosiers versus streets or anyone's PAX.

I'm looking at date aq because I want to figure out how to go as fast as the top people in my class.

[thrdeye]

Rife...simple. You need to spin the car more

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