2011 Green Grand Prix: Fri., April 15 (Watkins Glen, NY)

[geomartin]

Originally Posted by moTthediesel

That car got bumped from the X-Prize competition when they couldn't meet a 67 mpg threshold.

I'd say their 106 is likely every bit as accurate as my 42

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.

[geomartin]

I am including a hot link to our blog if anyone is interested. There are some pics of some of the vehicles at the Green Grand Prix also. I will include them in further posts.

[geomartin]

I have to post 1 more time then I will include the hot link

[geomartin]

Here is the link, sorry I don't post too much.


BITW Technologies

[RobertSmalls]

Just because a scale is in calibration doesn't mean it's accurate or capable for the application. Also, being in calibration in warm weather with no wind does not guarantee that it's in calibration in other conditions. We have scales at work that drift well outside the tolerances to which we're trying to measure when someone leans on the workbench that the scale sits on, or when the HVAC system is running.

The BITW Metro weighed in 6.21lbs lighter after the race than before, according to their score. That's probably pushing the limits of the Glen's measuring system.

[geomartin]

Originally Posted by RobertSmalls

Just because a scale is in calibration doesn't mean it's accurate or capable for the application. Also, being in calibration in warm weather with no wind does not guarantee that it's in calibration in other conditions. We have scales at work that drift well outside the tolerances to which we're trying to measure when someone leans on the workbench that the scale sits on, or when the HVAC system is running.

The BITW Metro weighed in 6.21lbs lighter after the race than before, according to their score. That's probably pushing the limits of the Glen's measuring system.

I had spoke with Bob Gillespie after your post. I don't understand how a car scale that has been certified for +/- 1Pound can give show a 0.21 Lb accuracy? Were you running the scale if so then we meet since I drove the car and saw it being weighed. I saw the weight of the car before annd after the event 1972Lbs (before event) and 1966Lbs (after event) sooooo the Lbs of fuel=6Lbs not 6.21Lbs

[moTthediesel]

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

[geomartin]

Tom, no offence taken. The scales were good for +/-1 Lb and the temperature was pretty much the same at the weigh stations. When we were participating in the X-Prize competition the fuel tanks were weighed also the BTU of the fuel and the plug to wheels elelectrical energy was measured. I hope that the competition next year can show how much electrical energy was consumed, in tons of coal burned to produce the KWH to charge the plug in hybrids and all electric vehicals. Do you have any thoughts on Well to Wheels or Plug to Wheels measurements?

[moTthediesel]

Originally Posted by geomartin

Do you have any thoughts on Well to Wheels or Plug to Wheels measurements?

Well, I understand the reason to try this as a means to level the field between cars that are ICE powered, and those that are hybrid or electric only. At the end of the day though, any such system is likely to be controversial to one group or another, (or all groups ) depending on where the arbitrary equivalents are set. It's an apples vs. oranges thing, and will probably never be resolved to everyone's satisfaction.

For my part, I regard these kinds of "competitions" more like playing golf. As you have no input over what other entrants are doing, it's best to concentrate on competing with only yourself. That's why I would like to see that the measurements done on my car are as accurate and repeatable as possible.

My result here last year (using the first click pump method) was a very satisfying 73 mpg. The car was brand new then, and as I didn't know what to expect of it, that seemed like a great mark. Now though, I've put well over 10k miles on the car, and as I have never been able to approach that number again, I now see it (nice as it is!) as unreliable. I have though, occasionally posted numbers in the mid-sixties, and have an average of 55 mpg overall. That's why my result in this years event, an all-time low, nearly 30% below my every day, street driving average, seems very suspect to me.

I intend to build a plug-in "test tank" that can be quickly and easily substituted for the in-car tank. It's advantage in any sort of competition is obvious, as any weight test will involve only the actual fuel, plus a few ounces for the plastic tank. Any discrepancies in the scale then will give linear errors in the result, unlike the compounding effect that we see when weighing the whole car.

More than that though, I think such a tank will be a great everyday development tool, allowing for meaningful evaluations of car mods and driving techniques without having to drive all the miles needed to make ordinary tank fills accurate.

Tom

[euromodder]

Originally Posted by moTthediesel

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.

In addition, weighing only 10 lbs, on a scale that is calibrated to 1 lbs.
That's a whopping error margin, it's ridiculously huge in comparison to what's being weighed.

I'm not surprised that participants are somewhat stunned at the results ...