Quote:
Originally Posted by geomartin
I had looked at the scales before the competition and they had an approved State of New Yorks Weights & Measures Department certification seal that is current. I am sure if any tampering with the scales had taken place, that the State of New York would like to know.  |
Please, I'm not implying that anything deliberate was done, and I'm sorry if you read it that way -- really!
What I'm saying is that using total car weight is maybe poor methodology for this purpose. I understand why it was done this way, as it is very difficult to determine fuel usage for cars that can't be equipped with electronic fuel instruments, and the scales are available at the track.
I don't know what the real accuracy of the scales is, but if they can show a 2# variation on a 250# Vespa (as mentioned earlier in this thread) how much can we trust it on a 2000# car?
The real problem is that what we want to weigh is 10# of fuel, but it's in a one ton or more car, that's only like 1/2 of one percent of the total. So even a fraction of a percent variation in the scale reading could skew the fuel weight result by several pounds. Also, since this method requires weighing the car twice, there is the potential to double the error.
For example, say the scale reads slightly (say 1/8%, or 2# or so) high when you are weighed initially. If it reads high again by a similar amount on the second weighing - fine, but suppose the scale reads low this time by the same amount? Now you're in the hole for 4 to 5 pounds or so.
I think the best method for doing this would be with a dedicated test tank that can be weighed before and after the run. That would be difficult to manage for an event like the Green GP, but it would give accurate, repeatable results.
Again, I want to say that I meant no offense by my previous posting. I simply wanted to say that any mileage results reached by this total car weight method may not be entirely reliable.
Tom