Why street racing is a crock to compare cars
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This is a discussion on Why street racing is a crock to compare cars within the Comparison: WRX vs World forums, part of the Community - Meet other Enthusiasts category; http://www.bimmerforums.com/forum/sh...threadid=36230 From bimmerforums, altimas.net, clubrsx and probably others. I tend to agree with the argument. I think it's why you ...

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    Why street racing is a crock to compare cars

    http://www.bimmerforums.com/forum/sh...threadid=36230

    From bimmerforums, altimas.net, clubrsx and probably others.

    I tend to agree with the argument. I think it's why you see some guys in supposedly slower cars always trying line up against faster cars... or similarly on the highway. Since they know they have some non-zero chance to "win" on reaction time alone, at least over very short distances.
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    Very interesting read and well articulated. A short street race is more about the driver's reaction time than whose car is faster.

    Apparently, the post was originally on ClubRSX.com. If you go to the link abovve, you have to go to two more links to read the original post, so here it is for your reading pleasure:

    Originally posted by Shawn on ClubRSX

    So I beat this guy at the stoplight, my car is so fast!
    or Why Street racing is a crock to compare cars
    How many times have you heard this? I have tried for years to explain to people just why a simple thing as leaving a 1/4 second later than the next guy can make a slower car beat a faster car. Or how on a rolling go, i.e. on the freeway, flooring it first can mean you will continue to pull away unless the other car is much faster. Someone finally posted to the BMW M Coupe board on bimmer.org exactly what happens. Kevin Willmorth explained it better than I have been able to and I asked his permission to post it. Below is his post (which he and I edited to create a more accurate and generic illustration):


    Anyone who drag races regularly knows that between two roughly equal cars, reaction time is king. Not top end speed, nor statistical B.S. datasheets. Reaction times are what will win a race, more often than equipment superiority, unless... the two drivers happen to get away at the same instant, which is highly unlikely in a street race.



    Here's how it works:
    You are at the light, and car "R" lines up on you. It's a dweebs toy, and you decide to go for it. Light turns green and you put the hammer down. But, man! he's off the blocks and pulling away already! You keep the hammer down, but just can't catch him. By the time you back off at 100mph, he's like 2 car lengths away. Must have been a more powerful car!


    Not necessarily.

    If at the launch they get 1/4 second on you, they are accelerating 1/4 second before you from that moment forth (you cannot get the 1/4 second back, it's gone forever). That's a whopping 22 feet at 60mph, assuming exactly equal cars and drivers. (BIG assumption, esp. in street racing).


    Let's look at this from the start: From the starting line... 1/4 second is a distance of 2.2 feet at 6mph (a door length), then 9 feet at 25mph (half a car length), then 16+ feet at 45mph (full car length), 22 feet at 60mph (he's pulling away!!!), then at 100mph, they got you by a total of 37 feet, or nearly 2 car lengths (you got whacked!) And that's with an exactly equal car, identical shifting at exactly the same RPM's!


    But wait you say! 1/4 second difference, that's a lot! Yes, it is for a pro drag racer, who operates under a .400 pro tree, or even a bracket racer running on a .500 second tree. But for a street racer, pulling on a street light? .250 is a close pairing! Heck .500 would be a great start. You aren't really sure when to go, no yellow staging lights... It won't seem like much time, and you might even figure, "OK, I missed the launch a tiny bit, but that's not important, I'll get him!"... you would be wrong of course, very wrong...


    Here's an interesting factoid. Reaction times are NOT equal in cars with identical 0-60 or 1/4 mile times! Heavy cars are generally slower reacting than lighter cars. Some suspension designs react faster than others. Short wheelbases react more quickly than long. Soft suspensions take longer to move the car forward after throttle is hammered down. Stiff cars jump more readily. Heavy wheels take more power to accelerate, (time to rethink those 20" rims!) Remember that 1/4 second reaction time is a culmination of YOUR reaction to the light PLUS the cars reaction to your giving it the boot!


    Just because the car you line up on has an inferior 0-60 time, does not mean you will beat it. It depends on the cars design, mass location, and a pile of other factors. It also depends on whether you get him off the line, or he gets you.


    Line up on a fast reacting driver, piloting his lighter car, and he can take you out, even if you are the faster car!

    For example, let's just say that in his "slower" car (car A) he gets you by that 1/4 second at the start. You take off in car B with your 1/4 second faster 0-60. Both cars will hit 60 at the same time, but you will still be behind car A! Up to this point, car A was only pulling away. From 60 mph on, you should be accelerating faster. Since you now have an equal,(soon to be faster) speed, the gap will finally stop increasing. Once both cars have an equal speed, the faster accelerating car, (B - this is you, remember?), will start to close that gap. So when will you finally pull even? Likely around 70-75 mph, depends on the car. So you see, that small start difference makes a huge difference in the outcome. How many street races do you know that go over 75? (I know they happen, but by them most are just racing in traffic and being stupid, not racing each other by that time). What if you started 1/2 second later? 1 second later? Count out one thousand one to yourself. See just how little a difference that can be. How many times can you think of where you hit the gas 1/2 second after the other guy? The average reaction time for most people is 1/2 second. So if you wait until you see him move, that is 1/2 second before you even hit the gas! And that assumes that your car reacts as quickly as theirs!

    The shorter a race is, the more critical the launch becomes. Since street races have neither a fixed set of starting lights, or a fixed distance, the outcome has less to do with the capability of the cars, than it does the arbitrary start and undefined length of the race itself. Get a head start on the opponent and cut the race short if you know you are slower. If you start late, just stretch the race to the longest possible distance and highest top speed! (We are assuming you are the "faster" car -oh and we will not be responsible for your speeding!)


    Because of these factors, street races are total crap as a judge of anything, other than who got off the line first, who's car might react the best to sudden off-line acceleration, and how long two idiots are willing to keep it up in the midst of traffic and road obstacles. Just be the quickest to leave, or stretch the race out longer, and you'll win more races, as long as the cars are anywhere near close in performance!

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    Registered User WRXed's Avatar
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    Definitely valid points, and in the real world, I can certainly see this being a factor. Having said that, I will state that comparing mag stats is still useful from the simple standpoint of a "baseline". Of course, we all know that mag stats can differ wildly, but I think you'll understand my point. The difference b/n a Yugo and a WRX is large enough that the reaction time is a moot point. The diff b/n the WRX and ? (Pick your favorite comparo) may not be enough to matter in real life. I think that for the most part people on ClubWRX are pretty good about stating the "facts" fairly, admitting that its a driver's race, etc. when the stats are close.
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    That is why driver is the most important aspect of drag racing.

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    Yo

    I agree ... but I can put myself in a "Street Race" situation everyday but NOT a "drag" race everyday. You're definitely right about 2 cars being almost equal in power ... it's all up the drivers. Just be safe and have FUN.
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    I would think races from a rolling start would make the reaction time less an issue and more a power vs power one.

    Ppower

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    Registered User pace's Avatar
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    The wonders of high-school math.

    The document does however articulate very well in laymans terms why the WRX is so good at winning races which conventional wisdom dictates it should not: Given two drivers with equal reaction times, the WRX pilot should be able to leave the line faster than much more powerful vehicles simply due to the traction factor.

    -Pace

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    Registered User pace's Avatar
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    Originally posted by Ppower
    I would think races from a rolling start would make the reaction time less an issue and more a power vs power one.

    Ppower
    The only reason the effect would be lessened is that the rate of acceleration is going to be lower at high speeds, and therefore the advantage gained from getting the jump will be smaller.

    This is rudimentary math. If two objects (a) and (b) start accelerating from the same point at the same rate, but object (a) moves first, it will gradually widen the gap on object (b). Since acceleration is rate of gain of velocity (obviously), the object that moves first will always be moving faster. This is essentially all that this document is communicating.

    Don't mean to sound like an a$$, and this isn't directed at you Ppower, but I'm just surprised that the content of that document would come as any kind of revelation to anybody that completed high-school.

    -Pace
    Last edited by pace; 06-28-2002 at 10:11 PM.

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    Makes sense - but I do point out that our WRX's are have about the fastest 0-60' times around

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    Originally posted by pace


    The only reason the effect would be lessened is that the rate of acceleration is going to be lower at high speeds, and therefore the advantage gained from getting the jump will be smaller.

    This is rudimentary math. If two objects (a) and (b) start accelerating from the same point at the same rate, but object (a) moves first, it will gradually widen the gap on object (b). Since acceleration is rate of gain of velocity (obviously), the object that moves first will always be moving faster. This is essentially all that this document is communicating.

    Don't mean to sound like an a$$, and this isn't directed at you Ppower, but I'm just surprised that the content of that document would come as any kind of revelation to anybody that completed high-school.

    -Pace
    Oh, I am not disputing the reasoning (have known about it and seen it before). Just the fact that if the race starts from a rolling start the reaction time, one vs another won't matter as much as long as they are close. The one fact the reasoning doesn't take in is driver error past the launch. Like a bad or missed shift. It also doesn't take into consideration power curves and gearing which make acceration non-linear.

    This is one reason too why I wish they (testing and measuring organizations) would go to a 0-70mph and not 60mph measurement. It would show more of a performance difference in cars.

    Ppower
    Last edited by Ppower; 06-29-2002 at 08:14 PM.

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    I do agree with the article but that is what racing is supposed to be about also. It isn't just how good your car is but how skillfull you are. If only the cars stats dictated the race then the car with the fastest acceleration and highest speed would win every race. But this isn't the case when drivers differ in so many ways. I think street racing is crap because of differences in road conditions or the fact that the road may not be exactly the same on both sides.

    I'll give an example I have a friend who raced his Camaro RS vs a Viper and won every time. He eventually realized that they guy with the Viper just had no idea how to drive it. The car was too much for him so they switched for one race (i wish i could do the same with a Viper owner) and smoked the camaro no problem.

    I'm just saying that yea a lot of cars are very similar in stats and that is the point. Racing is more about driving then about how good your car is. This is true until you pull up next to a mclaren F1 while you are in a normal street car (ex: toyota). Those differences can't be made up simply cause of the huge difference in acceleration times.

    Edit: Lets also not forget some people have stick shift and some have Auto. Some people can't drive stick very well, but drive autos very well in a straight line in accelerating.
    Last edited by nemesis099; 07-02-2002 at 08:20 AM.
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    street racing is not meant to be fair - it's not drag racing

    It's illegal, and it's fun.
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    Quote Originally Posted by Micah View Post
    street racing is not meant to be fair - it's not drag racing

    It's illegal, and it's fun.
    They do give you a good rush.
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    Street racing is great fun when the other guy does get the jump and you still catch and pass the rat bastard, while he's still on it. The math makes such fun all the better.
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    It's all about the thrill I think. I know when I pull up to a light and the dude in the civic next to me whats to go cuz he's revin' up then its on. Its totally worth the adrenaline rush, plus if you mess up on your take off or even if for some reason you suck and you lose, you can kick his or her ass at the next light.

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