Track Times Question...

jeepgclwj · #1 10-30-2006, 08:11 PM

Can someone help me understand how a car can trap a higher speed but be slower in the 1/4 mile...The reason I ask is my second run at the track with my Jeep I was beside Civic Si. My 1/4 mile was 15.872 at 84.67...His was 16.218 at 86.31....

I am sure its eay to figure out, but when I try and make sense out of it I get googly-eyed...

2.2 Straight six · #2 10-30-2006, 08:18 PM

you probably have a better torque-to-weight ratio.

torque defines acceleration.
power defines top speed.

302exploder · #3 10-30-2006, 08:35 PM

also you launch has an effect on it. im bad at explaining it, so ill just wait for chevytrucks to walk in and take care of business

clawhammer · #4 10-30-2006, 08:38 PM

Throughout the 1/4 you do not experience the same acceleration. Assuming you have no traction problems, you will accelerate the fastest at the beginning, and towards then end, when you're already going 80+ mph, the acceleration will be smaller due to larger wind resistance. Since the Civic trapped higher, it means that towards the end it was accelerating faster, which makes perfect sense, since it's a lot more aerodynamic than your Jeep. Makes sense?

jeepgclwj · #5 10-30-2006, 08:46 PM

Quote:

Originally Posted by clawhammer

Throughout the 1/4 you do not experience the same acceleration. Assuming you have no traction problems, you will accelerate the fastest at the beginning, and towards then end, when you're already going 80+ mph, the acceleration will be smaller due to larger wind resistance. Since the Civic trapped higher, it means that towards the end it was accelerating faster, which makes perfect sense, since it's a lot more aerodynamic than your Jeep. Makes sense?

yeah, I think it does...thnx

chevytrucks92 · #6 10-30-2006, 09:33 PM

Quote:

Originally Posted by 302exploder

also you launch has an effect on it. im bad at explaining it, so ill just wait for chevytrucks to walk in and take care of business

Lol.

Well, your trap speed is simple a formula based on the amount of time it takes your vehicle to go 66 feet at the end of the track. You know those set of lights you come to just before the finish line?? Those are the "mph lights".

I dont know exactly how its figured, but the amount of time it takes your vehicle to go that last 66 feet is what determines your trap speed. So the Civic probably took less time to go that last 66 feet then you did, even though you covered the 1/4 mile "quicker" then he did, but not "faster".

So I know you've seen me post up time slips, or atleast my times, and I also include an ET at 594'. Well, that's an odd ball distance, but that is simply the "mph lights" (for the 1/8th mile anyways) and some tracks give you your ET at that increment.

Here's a couple slips of mine from earlier this season when I still ran the Vega:

This is a perfect example of how trap speed works. The slip on the left is a faster ET, but slower mph then the slip on the right. It took me 0.4382 seconds to traverse the last 66 feet of the 1/8th mile in the 6.64 @ 102 mph pass where it only took me 0.4351 seconds to go the same distance in the 6.65 @ 103 mph pass. Granted, its a very slight difference (only .0031 seconds), but that slight difference (and that really is a slight difference, lol) netted me 0.75 more mph.

So, I was quicker in that last 66 feet, even though I had a slower overall run (in fact, slower in every incremement).

Slowprocess · #7 10-31-2006, 12:58 PM

Both my truck(on motor) and my SS have the same trap speed in the 1/4.....anywhere from 106-108. Only difference is my truck gets there about 1.4 seconds faster than my ss.

TheStang00 · #8 10-31-2006, 01:10 PM

i think a lot of it has to do with launch. think about it. if you launch well you run faster. if you have a crappy launch and spin a bunch then you could run slow but have a high trap speed due to having a high powered car.

Gohan Ryu · #9 10-31-2006, 02:19 PM

Maybe this will help: Someone beats you out of the hole and you start to reel him in slowly. Too slowly, he beats you to the end of the 1/4 mile. At that point you are going faster than he is because you are reeling him in, but the race ends before you can pass him. So he has a faster time, but you have a faster trap speed. Or vice versa, as in your situation.

That's the whole concept behind the ricer fly-by.

BlackGT2000 · #10 10-31-2006, 07:38 PM

Hey all I know is that it happens. My GT ran a 15.8 on its second run at 98 mph. Is that out of wack or what.

chevytrucks92 · #11 10-31-2006, 08:08 PM

Quote:

Originally Posted by TheStang00

i think a lot of it has to do with launch. think about it. if you launch well you run faster. if you have a crappy launch and spin a bunch then you could run slow but have a high trap speed due to having a high powered car.

You still wouldn't have any higher trap speed then normal though. I mean its not like you're going to pick up 2 or 3 mph because you spin off the line. And if you lose too much time in the 60', then you'll still have a slower trap speed becuase thats just that much less distance you have to accelerate.

I'm telling you guys. The trap speed is determined by how long it takes your vehicle to go that last 66 feet before the finish line.

jeepgclwj · #12 10-31-2006, 10:00 PM

^^^ makes sense to me...

TheStang00 · #13 11-01-2006, 12:10 AM

Quote:

Originally Posted by chevytrucks92

You still wouldn't have any higher trap speed then normal though. I mean its not like you're going to pick up 2 or 3 mph because you spin off the line. And if you lose too much time in the 60', then you'll still have a slower trap speed becuase thats just that much less distance you have to accelerate.

I'm telling you guys. The trap speed is determined by how long it takes your vehicle to go that last 66 feet before the finish line.

well thats not exactly what i meant. i guess i didnt do a very good job of explaining myself. i was basically saying the same thing as gohan ryu.

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