|08-14-2002, 04:34 PM||#1|
Join Date: Aug 2001
Location: San Pedro, CAVehicle:
1/4 mile numbers meaning...
can someone give an explanation of what those # means?
that is like slow time w/ high mph means...
can someone throw out a break down?
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|08-14-2002, 04:57 PM||#2|
Join Date: Sep 2001
Location: Melbourne, FLVehicle:
2008 Honda Element
I think what you are asking for is:
If I run a 10.xxx, but at a low MPH, ____ is what is
If I run a 16.xxx, but at a high MPH, ____ is what is
I don't know the breakdowns, but I couldn't exactly
figure out your first post, and thought I'd try to explain
(at least to myself ).
However, Supra's have a high top end. They trap at
high (120+mph?) speeds. So they run 10/11s, and
at a high speed = they have a high top end.
Our scoob's run 12-14s, at a lower MPH. So they have
a lower top end.
Hope that measly bit of info helps...I'm sure others will have
|08-14-2002, 06:45 PM||#3|
Join Date: Jul 2002
Location: Atlantic Beach,FlVehicle:
2002 WRX Silver
13.82 1/4 Almost Stock
and really low times with really high speeds means really good everything
i don't even know anybody who has the privilage of running with the big boys.....[email protected]
|08-18-2002, 10:48 PM||#4|
Join Date: Jan 2002
Location: [email protected] @ 5800 ft on 13TVehicle:
2002 Impreza WRX
Lots of details to watch for learn as you go
R/T Time that elapses from the lighting of the last amber light on the tree until the car moves enough to clear the stage beam. On a standard full tree a perfect R/T would be .500
In order to get the car to move the instant the green light comes on,you typically have to start releasing the clutch about the time the last amber comes on. Each car/drive combo is a little different but you want this number to be as close as possible to, but greater than .500. If this number is less than .500 you will get a redlight and be disqualified.
60' The time it takes the car to cover the first 60 feet of the track.
Timing begins when the front tires roll enough to clear the staging light, and ends when the front tires break a light beam at 60' down track.
The 60 ' time is considered the best measurement of your launch technique. It is a function of both the power available, tire traction and clutch engagement at launch. This number varies at the square of the acceleration rate. This means a very small change in this number indicates a significant improvement in acceleration. To cut the time in half you would need to increase the acceleration rate by 4x. A 60' time of 1.7 seconds is much better than a 1.79 second 60' time.
330 The time to reach 330 ft down track helpful in diagnosing some problems on the short end of the track, such as ideal shift point for low - second shift. Generally not used much by most racers.
1/8 The time to reach half track.
mph Speed at 1/8 mile. Many parts of the country have only 1/8 mile tracks so this helps compare times on 1/8 mile runs to runs on a full 1/4 mile. The difference between the ET and MPH at half track and the finish line is helpful in diagnosing problems at high rpm high speed end of the track. For example if the engine is having ignition problems the first sign of it might be that the engine goes a little flat near the end of the 1/4 mile and the difference between the 1/8 mile time and the quarter time is smaller than it should be.
1000' The time to reach 1000' ft down track
1/4 The time to reach the finish line. measured from the moment the front tire rolls out of the staging beam until it breaks the finish line beam.
mph The average speed over the last 66' ft of the track just before the finish line.
By looking at a source of multiple race results like the subaru registry you can see typical performance to expect from your car.
For example the best cars on the registry typically gain about 22 mph over the last 1/8 mile of the track, stock WRX's typically gain about 20 mph. By comparing your time over the last 1/8 mile to these benchmarks you can tell how you are doing at WOT conditions. If you have a free breathing upgraded turbo and intercooler expect to see speed gains of about 22 mph. If you car is more of a stock configuration expect 20 mph.
The trap speed is a very reliable measure of the "AVERAGE" power output of your engine under WOT conditions.
Look at your trap speed first, then compare it to the trap speed of some of the cars in the registry to see what sort of ET you should be getting with that trap speed. High trap speed for the ET generally means you are not making full use of the power available to you. Look at your launch technique, traction, and shift points.
Low trap speed for your ET generally means you're engine is not getting the job done on the big end of the strip. You have a good launch and traction in order to get the good ET, but the power is down for some reason on the top end. To confirm this double check the mph gained over the last 1/8 mile. If it is lower than the 20-22 mph you would expect, start looking for things that would effect high rpm, WOT power. Are you shifting up to 4th when you should stay in 3rd and run it to redline going through the traps ??
I think this is the sort of info you were looking for. There is no "book" on this subject just a lot of rumors, rules of thumb and common sense, with a fair share of fairy tales, and half truths added for good measure.
It is something you will learn over time with your car. For example I recall an article by a big name racer that he knew when his slicks were used up as his 60' times would increase by about 0.002 - 0.004 seconds and no amount of fiddling would get the 60' times back down until he got new racing slicks. That sort of thing is what each racer needs to watch for and how these detail strip times can help you if you're paying attention.
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