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Discussion Starter #1
So I had never driven a kart, until going to an indoor track in Atlanta (Andretti Speed Lab) last weekend. What a blast! It took a couple of laps to get used to the direct steering, but it just kept getting better and better from there. The speeds probably weren't very high, but it felt pretty fast on a short track. I was mainly blown away by how quickly you could corner. I was getting exhausted at the end of the 5 minute race, partly from the cornering forces. They were surprisingly easy to control at the limit, I never spun. Somebody needs to open one of these tracks in St. Louis, would make for perfect winter entertainment and practice!

Anyway, since our board manager races karts, I'm just curious: How does a kart running F125 in auto-x compare to one of the karts that they let everybody play with? I guess it would have much more power? The web site says that the karts at that track have 6.5 HP.

And if it's true that an Elise handles like a kart: Can I get mine tomorrow, please? :D :D
 

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Nice footage! I have seen karts on auto-x courses, I know that they are stupid fast. It's just sometimes hard to compare, driving something and watching it drive is entirely different.

I did some searching, and found numbers in the 30-40 HP range for a 125 shifter kart. Does that sound about right? So that would be about 4 to 6 times as much as the ones at the track.

Over 3 G's is very impressive. Hard to tell how much the ones at the track pulled. It certainly felt like much more than a car.
 

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Most indoor tracks are purposely relatively slippery.

A normal 125cc shifter is from 32-42hp depending if they are using a stock engine or it's been built. I have a built engine. :)

The g-forces is a major reason we have to wear the safety gear, a neck brace, rib vest. Not for impact like one might expect, but for the normal loading of racing. You have a very real possibility of breaking your ribs on the sides of the seat from the g-forces if you do not wear a vest. And it is almost impossible to keep your head straight up without the neck brace.

When I first started, I thought I could go out on the track with my sunglasses on under my full face helmet. The sunglasses were on the side of my face after the first turn.
 

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I read about 3G forces on the Champ car. I thought it was mostly possible due to enormous downforce they develop.
AFAIK, karts don't have downforce devices. How can they develop same 3G as in CART? I don't understand the physics here.



Randy Chase said:

Shifter can do 0-60mph in around 3.5 seconds, top speed approaching 130mph. Turning forces over 3 Gs. It's a bit brutal. And you are always busy shifting.

[/QUOTE
 

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Discussion Starter #6
I was surprised by the number, too. They have the very low weight going for them. The center of gravity is also low, which should cause less weight shift than a typical car (the track is more narrow, though). But 3G still sounds very high.

Doing some math, if an Elise can pull 1.3G, and a kart 3G, the kart could maintain a 50% higher speed through a steady state turn. That would be an enormous difference. Because a kart is much smaller, it can also drive a shorter line through an auto-x course, while having larger turn radii. Yet, according to the PAX, a shifter kart (F125) is "only" about 10% faster than a moderately prepared Elise (ASP).
 

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ConeFusion said:
Doing some math, if an Elise can pull 1.3G, and a kart 3G, the kart could maintain a 50% higher speed through a steady state turn.
I believe there's a squared in there. In other words, you can't just say that because it holds double the g's that it can double the speed. g's are m/s/s, speed is m/s - "speed v g-load" is probably an asymptotic-ish curve so even as you go up to 4 and 5 g's (if that's physically possible), you won't get much more holding speed, or, looking at it another way, increasing your speed around a corner by just a little bit will increase the g load a lot (above a ceratin point).
 

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BrianK said:
I believe there's a squared in there.
Exactly, that's what I calculated. sqrt(3.0 / 1.3) = 1.5191. So the kart is 1.5191 times as fast, or a bit over 50% faster.
 
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