Comparing car lap times: Equal tires?

[DarkSunrise]

Originally Posted by fatoni

i got "different skidpads" from the fact that you are using data to support your claims that was collected on..."different skidpads"

I didn't want to get drawn into this debate, but felt the need to correct that statement. Edmunds' skidpad measurements (and actually all their testing) is quite regimented and is as consistent as you're going to get. They have a single test facility that they use, they've got a set policy for fuel and tires, they do repeated runs in multiple directions (CW and CCW on the skidpad), use asphalt that complies with the friction coefficient requirements of the FMVSS-135 brake-certification test, use timing lights instead of hand timers for the skidpad, etc. Also the weather conditions in southern california are about as temperate and consistent as you'll find in the world. To the extent you can compare cars' performance using objective testing, Edmunds has done it.

http://www.insideline.com/features/p...s-gallery.html

Now if you're arguing you can never compare objective numbers on cars because of the variables involved, that's a different story, but I know you don't believe that yourself as you've obviously quoted numbers before (also don't kid yourself, during development, even automobile OEMs will record objective performance data and benchmark against competitors).

Originally Posted by fatoni

i know we can analyze the term handling but i think objectively it might still be up for debate as to which is the best handling car. obviously the vette puts up tons of grip. its obviously the better high speed handler (thats what it was designed to do) but i wouldnt be surprised if figure 8s and slalom tests show the elise performs better in the low speed and transient handling areas

The slalom numbers are there in my post you quoted. That's the second number in the "triple slash". The ZR1 is faster.

1.06 g / 74.7 mph / 96 ft -- Corvette ZR1 (Michelin PS2)
1.03 g / 71.6 mph / 109 ft -- Elise (Yoko A048 LTS)

The Elise also loses in MT's figure-8:

23.7 seconds @ 0.87 g -- Corvette ZR1
24.8 seconds @ 0.75 g -- Elise

Also just as a general note, the problem with your concept about leaving tires stock and drawing conclusions about the chassis from that is that it can lead to some absurd conclusions. To take an extreme example, a 2013 Mustang comes from the factory with all-season tires. A 2013 STI comes with summer tires. If you tested both cars in the snow to see which one did better in it, the Mustang would destroy the STI. But no one would seriously argue the Mustang was a better car for the snow than an STI. Why? Because once you match tires on both (snow v. snow, etc.) you'll find the STI is a much better car through snow due to its lockable center differential and limited slip differentials in the front and rear. Tires have to be taken into consideration when comparing cars. That's why tires are equalized across the board in just about every competition event, even in the so-called "stock" classes of autocross.

[xwd]

Not sure why people try to reason with fatoni, who has been proven to ignore rational thought over and over again.

[carbonBLUE]

Originally Posted by fatoni

a peak of .98g doesnt count for much. those kind of singular instances are not really related to static sustainable lateral grip. that being said, you could probably set your sights a little higher than that. an na miata with decent coilovers and 225 rs3s will do 1.25-1.33g on the skidpad.

I recorded that on the street with 40psi in the srock tires, and I wasnt pushing all that hard

[gmookher]

she'll do 1.00g with stock suspension and star spec z1...

[fatoni]

Originally Posted by DarkSunrise

I didn't want to get drawn into this debate, but felt the need to correct that statement. Edmunds' skidpad measurements (and actually all their testing) is quite regimented and is as consistent as you're going to get. They have a single test facility that they use, they've got a set policy for fuel and tires, they do repeated runs in multiple directions (CW and CCW on the skidpad), use asphalt that complies with the friction coefficient requirements of the FMVSS-135 brake-certification test, use timing lights instead of hand timers for the skidpad, etc. Also the weather conditions in southern california are about as temperate and consistent as you'll find in the world. To the extent you can compare cars' performance using objective testing, Edmunds has done it.

http://www.insideline.com/features/p...s-gallery.html

Now if you're arguing you can never compare objective numbers on cars because of the variables involved, that's a different story, but I know you don't believe that yourself as you've obviously quoted numbers before (also don't kid yourself, during development, even automobile OEMs will record objective performance data and benchmark against competitors).



The slalom numbers are there in my post you quoted. That's the second number in the "triple slash". The ZR1 is faster.

1.06 g / 74.7 mph / 96 ft -- Corvette ZR1 (Michelin PS2)
1.03 g / 71.6 mph / 109 ft -- Elise (Yoko A048 LTS)

The Elise also loses in MT's figure-8:

23.7 seconds @ 0.87 g -- Corvette ZR1
24.8 seconds @ 0.75 g -- Elise

Also just as a general note, the problem with your concept about leaving tires stock and drawing conclusions about the chassis from that is that it can lead to some absurd conclusions. To take an extreme example, a 2013 Mustang comes from the factory with all-season tires. A 2013 STI comes with summer tires. If you tested both cars in the snow to see which one did better in it, the Mustang would destroy the STI. But no one would seriously argue the Mustang was a better car for the snow than an STI. Why? Because once you match tires on both (snow v. snow, etc.) you'll find the STI is a much better car through snow due to its lockable center differential and limited slip differentials in the front and rear. Tires have to be taken into consideration when comparing cars. That's why tires are equalized across the board in just about every competition event, even in the so-called "stock" classes of autocross.

i started talking about the different skidpad after you corrected his skidpad force of the zr1. he said he was using your data but saying that the zr1 pulled 1.02g on a skidpad. he came to the conclusion that the elise handled better than the zr1. not even you agree with that. either he is using more than one set of data, or the margin of error is too great for an objective test. either way, he came to a conclusion that is skewed.

im not coming to any conclusions about chassis or anything. the only point ive ever been making is that if you want to do a stock test, drive the car the way the manufacturer delivered it. if you want to change things to shed light on a cars performance potential, great. just realize that frs people are going to want to change the tires, 370z guys are going to want to change the brakes, ms3 guys are going to want to tune out the torque throttling in 1st and 2nd, v6 mustang guys are going to want to rid the car of the governor etc.

making the use of the stock class (or any class really) allowing for changing tires could be used in the same argument for allowing a change of shocks or sways or brake pads. the only time ive ever said that changing tires isnt fair is when comparing cars values to eachother. when you change the tires on the frs, it loses value

[Kunzite]

Are you talking about me? OK, let's cut the BS:

Originally Posted by Kunzite

What are the Edmunds numbers for the ZR1? 1.02g was all I found.

Obviously (but not to you, it seems) I was looking for numbers comparable with those posted by DarkSunrise; and I wasn't so sure about what I've found, so I asked. Thankfully DarkSunrise provided the correct figures.
I don't remember claiming the Elise handles better than the ZR1; I can't, since I've driven neither.

Unfortunately you're going way further than that; you're working hard on persuading people that comparing cars with the same tires is "unfair", and would generate some sort of tuning spree (oh, really?). You're completely rejecting all the arguments about why someone would want to compare cars with the same tires.
In other words, you're scared about putting good tires on the GT 86, it would be too good for your liking.

[fatoni]

Originally Posted by Kunzite

Are you talking about me? OK, let's cut the BS:

Obviously (but not to you, it seems) I was looking for numbers comparable with those posted by DarkSunrise; and I wasn't so sure about what I've found, so I asked. Thankfully DarkSunrise provided the correct figures.
I don't remember claiming the Elise handles better than the ZR1; I can't, since I've driven neither.

Unfortunately you're going way further than that; you're working hard on persuading people that comparing cars with the same tires is "unfair", and would generate some sort of tuning spree (oh, really?). You're completely rejecting all the arguments about why someone would want to compare cars with the same tires.
In other words, you're scared about putting good tires on the GT 86, it would be too good for your liking.

okay maybe you didnt say the elise outhandled the zr1. this has been going on for a while and im not going to reread all this jazz for that sake. sorry dude.

slow down. im not rejecting any thing. the only thing i ever said was unfair was changing tires in a stock comparison.

[Kunzite]

Did it ever crossed your mind that maybe, just maybe we're not interested in your kind of stock comparisons?

[fatoni]

Originally Posted by Kunzite

Did it ever crossed your mind that maybe, just maybe we're not interested in your kind of stock comparisons?

if by my kind of stock comparison you mean the industry standard for stock comparisons, yes. did you ever consider that being interested in something doesnt make it fair or rational?

[Kunzite]

Industry standard? Do you even know what an industry standard is?

Oh, now the clearly explained reasons why one would want a same tires comparison are "irrational". You're irrationally scared at the thought the GT 86, with proper tires, can also give some decent numbers.

Obvious troll is obvious. And, as dwx said, would ignore rational thought over and over again.

[DarkSunrise]

Originally Posted by fatoni

making the use of the stock class (or any class really) allowing for changing tires could be used in the same argument for allowing a change of shocks or sways or brake pads. the only time ive ever said that changing tires isnt fair is when comparing cars values to eachother. when you change the tires on the frs, it loses value

I actually agree you can make arguments to equalize brake pads, fluid, and tires. Tires will make the largest difference on most cars though -- I think that's why people are adamant about at least equalizing tires before comparing track performance.

Sways are technically allowed in stock class autocross, but IMO that's really a large compromise to get more people involved in the sport. At that point, you're clearly changing the car's suspension from my perspective.

[WolfpackS2k]

Upgrading dampers is also allowed in stock class autox, as long as they use the stock mounting points.

[fatoni]

Originally Posted by DarkSunrise

I actually agree you can make arguments to equalize brake pads, fluid, and tires. Tires will make the largest difference on most cars though -- I think that's why people are adamant about at least equalizing tires before comparing track performance.

Sways are technically allowed in stock class autocross, but IMO that's really a large compromise to get more people involved in the sport. At that point, you're clearly changing the car's suspension from my perspective.

yeah, im not actually crazy. its just that people hear a fraction of what im saying than then jump to conclusions. i understand if people want to try to equalize tires and that might move toward a more realistic performance comparison. ive just been saying that doing all that other stuff will to. then it really hits the fan for some reason.

i think that sways are part of the suspension too (so are tires imo but thats beside the point). im just bringing it up because one of the largest arguments people make is that you are allowed to change tires in stock classes.

[Bugbeat]

Originally Posted by DarkSunrise

On one of the spectrum, if you work for a car magazine whose audience is the general public, then you should compare cars as they come from the factory (stock tires). Then again, to the general public, track times should mean next to nothing anyway.

On the other end of the spectrum, if you're into autocross or tracking, then you should absolutely compare cars on equivalent tires. Why wouldn't you? Tires are probably one of the most commonly changed-out consummables on cars that see track time and can make a significant difference in handling and laptimes. For any kind of competition event, tires are largely equalized across the board anyway.

This here is why I don't read MT or C&D (or any of the big publications, really). Their size allows them access to certain resources smaller publications like Grassroots Motorsports can't, but they're just so... corrupted. In addition they have to almost cater to the public while maintaining a marginal gearhead fanbase - almost like Top Gear to an extent.