[tech] Why is the 60' ET so important?
12-30-2005, 04:39 PM
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[tech] Why is the 60' ET so important?
by Mark Towslee
If you've done any drag racing, you've probably noticed that racers seem obsessed with 60' ET's. There's a good reason for this. The first 60' of the track set the stage for the rest of the run and has a huge effect on the ability to "run the number" when bracket racing. Many beginning racers seem more concerned with top end mph thinking that if the car goes faster at the end of the track they'll pick up ET. However, top end speed isn't really as important as it first appears.
Here's why - Think about the percentage of time that you spend traveling the first 60' compared to the last 60' and you'll see that you spend a relatively large amount of *time* in the first 60' of the track. Now lets take that out to 330' and the compare it to the last 330 feet of the track ...
I went through some timeslips and found a car that ran 10.21 in the 1/4 mile. Now lets do some analysis:
60' = 1.470 or a total of 14% of the total ET
330' = 4.167 or a total of 41% of the total ET
So, you travel 25% of the total distance and you've spent 40% of your total ET to travel that first 25% of the track.
Now lets look at the 1000' to 1320' time compared to the 330' ET:
To get from the 1000' timer to the 1320' timer it took 1.73 seconds (10.213 1320' ET - 8.48 1000' ET) for a total of 17% of the total time. You've only spent 17% of your total ET to travel the last 25% of the distance.
So, as you can see, it takes almost as much *time* to travel the last 320' as it does the first 60' of the track and it takes 2.4 times longer to travel the first 330 feet as it does to travel the last 330' feet - actually 320' feet but its close enough for this comparison.
This is why you gain ET by concentrating on the first few feet of the track. You spend a proportionately greater deal of *time* in the first few feet and since ET is *time* it's easier to gain ET by concentrating on the launch.
From my own personal experience: My car picked up almost .3 in the 60' and about .4 overall when I switched from a 2500 converter to a 3500, MPH actually stayed about the same. It would have taken an awful lot of MPH at the top end to pick up that much ET.
If you've done any drag racing, you've probably noticed that racers seem obsessed with 60' ET's. There's a good reason for this. The first 60' of the track set the stage for the rest of the run and has a huge effect on the ability to "run the number" when bracket racing. Many beginning racers seem more concerned with top end mph thinking that if the car goes faster at the end of the track they'll pick up ET. However, top end speed isn't really as important as it first appears.
Here's why - Think about the percentage of time that you spend traveling the first 60' compared to the last 60' and you'll see that you spend a relatively large amount of *time* in the first 60' of the track. Now lets take that out to 330' and the compare it to the last 330 feet of the track ...
I went through some timeslips and found a car that ran 10.21 in the 1/4 mile. Now lets do some analysis:
60' = 1.470 or a total of 14% of the total ET
330' = 4.167 or a total of 41% of the total ET
So, you travel 25% of the total distance and you've spent 40% of your total ET to travel that first 25% of the track.
Now lets look at the 1000' to 1320' time compared to the 330' ET:
To get from the 1000' timer to the 1320' timer it took 1.73 seconds (10.213 1320' ET - 8.48 1000' ET) for a total of 17% of the total time. You've only spent 17% of your total ET to travel the last 25% of the distance.
So, as you can see, it takes almost as much *time* to travel the last 320' as it does the first 60' of the track and it takes 2.4 times longer to travel the first 330 feet as it does to travel the last 330' feet - actually 320' feet but its close enough for this comparison.
This is why you gain ET by concentrating on the first few feet of the track. You spend a proportionately greater deal of *time* in the first few feet and since ET is *time* it's easier to gain ET by concentrating on the launch.
From my own personal experience: My car picked up almost .3 in the 60' and about .4 overall when I switched from a 2500 converter to a 3500, MPH actually stayed about the same. It would have taken an awful lot of MPH at the top end to pick up that much ET.
12-23-2006, 09:03 AM
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for streetcars the 60 is extremly important if you shave a tenth off your 60 its 2 tenths at the top end or more. however for for cars faster then 9.50's the most important is the 330 because alot of cars will stilll break lose at the 330. and my buddy danny blier from quebec with his blue sso car can break lose at 1000 feet. they say the perfict pass is one that you can see black marks all the way down the track, not from spinning but from hard hooking under power.
12-23-2006, 12:39 PM
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well, since were on the topic of 60' times and 330's, it would be good to mention that the 60' is where your cars suspension and weight really comes into play.
We all know that we want the front end of the car to come up so the suspension is at full droop in the front off the launch. That's why we usually run 90/10 shocks/struts up front for drag racing, as well, some people go as far as to remove the front sway bar, since you're hopefully not hitting any hairpins or esses at the end of the 1320.
You've got your weight transfer good.....now your main focus should be coming off the line as straight as possible. Simple math tells us that the shortest distance between 2 points is a straight line so the less your car moves around while going down the track, the better your ET's.
Proper weight balancing is part of the problem, as well as the rear axle angle.....seems to me I see more and more adjustable ladder bars wich will allow you to adjust the angle of your rear axle. If you come off the line pointed to the left, the right side of the axle needs to go back, so a simple adjustment to make the right side ladder bar and you can lengthen the bar and move the axle back..and you just do the opposite if the car points to the right off the line. A lot of 4 links these days are adjustable too.
Anyway, something to think about.
We all know that we want the front end of the car to come up so the suspension is at full droop in the front off the launch. That's why we usually run 90/10 shocks/struts up front for drag racing, as well, some people go as far as to remove the front sway bar, since you're hopefully not hitting any hairpins or esses at the end of the 1320.
You've got your weight transfer good.....now your main focus should be coming off the line as straight as possible. Simple math tells us that the shortest distance between 2 points is a straight line so the less your car moves around while going down the track, the better your ET's.
Proper weight balancing is part of the problem, as well as the rear axle angle.....seems to me I see more and more adjustable ladder bars wich will allow you to adjust the angle of your rear axle. If you come off the line pointed to the left, the right side of the axle needs to go back, so a simple adjustment to make the right side ladder bar and you can lengthen the bar and move the axle back..and you just do the opposite if the car points to the right off the line. A lot of 4 links these days are adjustable too.
Anyway, something to think about.
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