Road and Track magazine published the tested the 50th Anniversary Corvette last month. They showed it did the quarter mile at 13.3 seconds at 101 mph if my memory serves me correctly. I thought the speed should be close to 110 mph so I studied the data. In the time to speed section, it showed 0-90 in about 9 seconds, 0-100 mph in about 11 seconds. But took 1.4 seconds to go from 100 to 101 mph. I thought it was a mistake, so I emailed them.

Here is their response:

Quote: Road & Track Magazine

This is a response to your question sent on 7/7.

We get this question a lot. We report all acceleration times as corrected for a one-foot roll-off. This is an NHRA standard. In a drag race the car stages roughly a foot before the light beams. We simulate this and report numbers that someone would receive if they were to test there car at a drag strip. However there is an exception. We report the 1/4-mile speed, at that which the car would actually be traveling at the quarter-mile.

Just for curiosity's sake, I went and looked up the test. The time difference you noticed of 1.9 seconds is the combined time taken to travel the first foot (with a lot of wheel spin), and to increase it's velocity by 1.1 mph.

Thanks for paying attention.

From Road & Track Magazine.
Unquote.

I did not understand so I called them. After talking to the one of the testers, they use a radar gun to test the acceleration. But they make some kind of correction for the fact that at the strip, a car stages and gets a 1-foot running start in the beginning. OK, I understand that but he said they adjust for the first foot and it ends up 101 mph.

Does anyone understand this? I checked another test in the same issue. It was the supercharged Mustang Cobra. They showed it doing 13.4 sec at 108 mph. I can’t see how the Mustang Cobra could be so close in e.t. but 7 mph faster in the quarter.



[Modified by Mez, 4:37 PM 8/1/2002]

 

I also don't understand how the car mags' times are often SO high.....an '03 cobra should run 12.8-13.0 @ 111-113 easily, and the 50th anv. vette (m6) should run about 13.3 @ 108-110.

 

there are a number of confusions with the way the mags test....

I prefer the methods used by Car & Driver. They are using a new GPS based system. mucho accurate.

 

Well, when I talked to him, I thought I was being dense because I did not understand how the Vette could loose approx. 9 mph due to the 1 foot roll out he described in their testing procedure. One possibility is they subtract the speed at the 1 foot which could be 9 mph.

Let me try to repeat what he told me on the phone.

They do not test on the drag strip. They set up a radar gun with a computer recording equipment and record time to speed and 1/4 mile data.

They make an adjustment for the fact that at the drag strip, there is 1-foot between the starting line and the last staging light. However, his statement that it took 1.9 seconds to go a foot does not make sense since stock 60 ft times are 2.2 seconds. And if you simply adjusted the 1/4 by a foot at the start, that should not cost it 9 mph. That I could believe, but I don't understand why they would do that since they simply could provide the speed at exacty 1/4 mile using the radar gun.

So, I am really confused.....

Anyone have an answer??

 

The tester said they are in the process of converting to that system and will actual use the same testing equipment as Car & Driver.

 

if i recall correctly, at a drag strip the "timing traps" are something like 132' and straddle the end of the 1/4 mile. so that the top speed can actually occur PAST the end of the 1/4 mile (but still within the timing trap)

 

I sent another email yesterday but no reply yet.

Here is what I said:

Quote
======================================== ===========
Its me again. Sorry to be a pest, but this is bugging the hell out of me.
Let me see if I have this right.

Here is an example:

1. Test starts from standing stop using radar gun.
2. Car starts by dropping the clutch at 2500 rpm.
3. Car travels 1 foot. Test computer records time and speed to travel
1-foot, say .5 seconds and 9 mph.
4. Car timed to reach various speeds 0-60, 0-80 and so forth from standing
start. No adjustment is made to data published.
5. Car travels exactly 1320 ft from standing start point in 12.9 seconds
with terminal speed of 110 mph.
6. You add .5 seconds from step 3 above to 12.9 seconds from step 5 to
arrive at 13.4 seconds.
7. You subtract 9 mph from step 3 above to arrive at 101 mph.

Let me know which steps I am wrong. Has this testing procedure been
published in Road & Track? I can look it up if it has.


Thanks,
Tom
======================================== ===========
Unquote