Why is quicker not faster???
- Thread starter Draco1340
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Draco1340
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Mr. Bogus makes sense, BUT,
If you accelerated QUICKER for only 9 seconds in your example, that means your MPH at the 60Ft mark was much higher, and from that point on, you were starting with a higher speed. The math says it should equal out.
GotBusa's equation he quotes also says MPH is independent of ET. Its dependent on HP and mass. I use this equation all the time. Emperically though, a good 60 does hurt the MPH.
I'm going to try plotting out speed / time plots today at work (while I should be doing something useful). My datalogger has this information. I just never plotted it out. Data to follow.
That plot will be really interesting because the curve will give a much better idea as to exactly how linear the plots are. Looking forward to seeing your info, you should get one of those tinted screen protector things that keep people from seeing what your working on. how much data do you carry in regard to weather conditions, while your messing around on the clock if you could look at a few runs to see how any head winds may have effected some of them.
"O"
"O"
a 1/10 in the first 60' is 2/10 at 1200' so for every tenth you loose in the first 60', you get an extra 1/10 to accelerate on the other end.. (1/10th is about a car length for anything running slower than about a 9 flat) As MPH is pretty much a function of HP and not really ET, it kind of makes sense..
the extra 1/10 at the 1200'+ mark is going to show up as more mph..
you need to pull the incremental times for every 100' (tracks do not do this) but you will see it if you have an accelerometer in the car.. Seems all pretty voodoo to me too but it was how it was shown to me by a pretty smart crew chief.. made sense then, only sort of now
is a lot easier to see on a chart with the accelerometer
This conversation came up when we ticked off a 7.50 at 55mph..
the extra 1/10 at the 1200'+ mark is going to show up as more mph..
you need to pull the incremental times for every 100' (tracks do not do this) but you will see it if you have an accelerometer in the car.. Seems all pretty voodoo to me too but it was how it was shown to me by a pretty smart crew chief.. made sense then, only sort of now
is a lot easier to see on a chart with the accelerometerThis conversation came up when we ticked off a 7.50 at 55mph..
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what do you guys use for data loggging? any hard printouts?.
I am in the mist of getting everything together, I need the dynojet hub harness I have the LCD display for saving to an SD card, If I had it to do over I would have just bought an inovate setup, I have some experience with their products and they have some really cool things like saving the software on your Iphone or Ipod for portable reading purposes. Draco has published things like like bottle pressure over time and some other things plus when I met him at the track he told me what he has so he is a good resource for some of that hard data. So Draco to add to your task list while you are at work just out of curiosity would you plot out a nitrous run of speed vs time with and overlay of bottle presure with time? Just curious the differences not only of NA vs N2O but also a piece of data showing the effect of pressure on the acceleration. Hope your boss doesn't monitor your computer, or perhaps he/she will think it is actually work your doing!!!
Mr Brown
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The flaw here is that your mph @ 60' ISN'T higher. You just got there sooner.
Now stop making my head hurt.........
The flaw here is that your mph @ 60' ISN'T higher. You just got there sooner.
Now stop making my head hurt.........
Slower 60' = more time in the speed traps = more MPH if the rest of the data agrees with what I have found.. Need a engineer here to sort the formula 
now my head hurts... would be a guess but there is probably some point of diminishing returns on the slow 60' theory... back to data acquisition...
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Why do I consistently get more MPH at the quarter when I spin and get a fairly crappy 60'. For example:
I get a better time when spinning off the line also. I have a couple theories on this without going into the mathmatics of the issue. One, as long as you are not blowing your tire plum off...your bike is in it's power range when slipping the tire some and keeps the rpm's higher thus getting you going that much quicker at the time you reach the 60ft mark. Your launch time may not look that good but it's better than launching hard with the front tire sky high and only being able to use 60% throttle. I like the latter though, it's more fun.
I get a better time when spinning off the line also. I have a couple theories on this without going into the mathmatics of the issue. One, as long as you are not blowing your tire plum off...your bike is in it's power range when slipping the tire some and keeps the rpm's higher thus getting you going that much quicker at the time you reach the 60ft mark. Your launch time may not look that good but it's better than launching hard with the front tire sky high and only being able to use 60% throttle. I like the latter though, it's more fun.
the quicker you go the less time you have to accelerate over the measured distance.
In your data loggs what is your speed at different points in time(ie. 3sec:mph, 5sec:mph, 7sec:mph)? How different are these speeds from pass to pass at each measured time?
In your data loggs what is your speed at different points in time(ie. 3sec:mph, 5sec:mph, 7sec:mph)? How different are these speeds from pass to pass at each measured time?
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Mr Brown
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That I understand!here is an easier one.. Deep Staging will decrease MPH and increase ET
it would be best to get just an NA run to plot things out. That alone has enough variables to make your head spin. I can get a high terminal speed for a given distance if is slip the clutch more during a launch so that the engine is at a better point in its power band...
Draco - it's kind of funny... your focus is time over distance (quick for drag racing) while my focus is speed over distance (fast for LSR).
I can get a high terminal speed for a given distance if is slip the clutch more during a launch so that the engine is at a better point in its power band...Commuta,
Thats kind of why I asked for a plot with no nitrous and some idea of wind conditions and then some with nitrous and speeds vs bottle pressure. This is so much better than what is a TRE!!
Draco - it's kind of funny... your focus is time over distance (quick for drag racing) while my focus is speed over distance (fast for LSR).
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that is why I would like to see the 100' increments.. if their data logging gear is that good, I bet you might get to see this.. All we had was the accelorometer vs time line, no mph
The explanation you gave is what I was told a long time ago, just took some data logs overlapped to see the thing in action... trying to analyze the thing will make blood vessel's pop in your head ..
loggers have gotten really good. I know for mine I can log sensors in 0.02sec (50 Hz) intervals if needed.
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Draco1340
Registered
Here is what I plotted up so far. I plotted a raw data file showing Throttle, RPM, and A/F just to keep the immages simple, and then show speeds at the various distances. I've turned off the N2O info because it makes the graph confusing. Regarding O Factors questions regarding nitrous, its a pair of #23 jets in the air box inlet, no filter, with a Nitrous regulator turned down to 450 psi. This effectively provides a very small 18hp shot. I only use about 2.7 Oz per pass. Progressive activation is 1 second after wide open throttle. Because of the regulator and small shot, nitrous pressure is constant to within 40 psi over entire pass. Also, this is "street-fighter" class which is no autoshifter, no slick, no bar, no 2 step, no box, no sliders. Its a true streetbike class.
The first graph is a relatively "good" pass of 8.858 seconds. You can see that I reach the 60' only going 46 mph based on the database I have. In a "good" launch I get the clutch out in 1.1 seconds, and the motor is pulling at 7500 rpm from the start. On a perfect launch, I would have the throttle pinned immediatly, but this one was OK. See below.
ImageShack Links Do Not Work
The next graph shows a crappy launch. 9.01 quarter, with a very slow 60' of 1.532 seconds. You can see I let the clutch out too quickly and the motor bogged down to 4k rpm. Throttle was pinned quickly, but the motor wasn't pulling in the power band. You can see that the MPH at the 60' was actually FASTER (60 mph vs. 46 mph). WTF??? At those speeds things like headwinds and such don't matter much. At that point I wasn't on the spray yet.
I need to overlay the curves after converting them to speed / distance curves. Right now they are RPM / time curves, which aren't as obvious, but you can see that indeed, Quicker is slower.???
ImageShack Links Do Not Work
The first graph is a relatively "good" pass of 8.858 seconds. You can see that I reach the 60' only going 46 mph based on the database I have. In a "good" launch I get the clutch out in 1.1 seconds, and the motor is pulling at 7500 rpm from the start. On a perfect launch, I would have the throttle pinned immediatly, but this one was OK. See below.
ImageShack Links Do Not Work
The next graph shows a crappy launch. 9.01 quarter, with a very slow 60' of 1.532 seconds. You can see I let the clutch out too quickly and the motor bogged down to 4k rpm. Throttle was pinned quickly, but the motor wasn't pulling in the power band. You can see that the MPH at the 60' was actually FASTER (60 mph vs. 46 mph). WTF??? At those speeds things like headwinds and such don't matter much. At that point I wasn't on the spray yet.
I need to overlay the curves after converting them to speed / distance curves. Right now they are RPM / time curves, which aren't as obvious, but you can see that indeed, Quicker is slower.???
ImageShack Links Do Not Work
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