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CLOSED 2016 Rules Change - Change Dyno Variance 4hp to %


Michael G.

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Current rule

To allow a small safety margin for dyno variance, a forgiveness of 4WHP will be given to cars with WHP greater than WTQ and a -4 factor will be applied to the formula for cars using the averaging method for WTQ greater than WHP.

2015 GTS rules 2015 NASA CCR

Proposed change

Switch from the fixed factor of - 4 WHP to percentage base.

Reason

To provide equal value of the margin for different classes, still accommodating the variance.

Proposed wording

To allow a small safety margin for the dyno variance, a forgiveness of equal to 1% of the average WHP calculated using the online method taken from the highest run during testing. In case if the car is impounded and dyno tested more than once during the event - the allowance is available only first time at the dyno - to align and accommodate the differences with the declared dyno values

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If the percentage is 2% or higher: YES

The proposed rule of 1%: NO

 

EDIT: It should not be a 1 time allowance. Dynos change over time with weather and operator error.

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Agree on this change IF you change it to 2%. The reality is, anyone that is cheating by 3% or more will get caught, DQ'd and the level of personal embarrassment will keep them from non-compliance at any future event. A 2.5% variance will not win or lose a race for someone over race craft. A 2% variance should help with the inconsistency of Dyno's we've seen over the years.

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This rule only works if the dyno used for compliance is accurate and consistent. Over the four days at the NASA ECC my car gained 10hp with ZERO changes to the car.

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Current rule

To allow a small safety margin for dyno variance, a forgiveness of 4WHP will be given to cars with WHP greater than WTQ and a -4 factor will be applied to the formula for cars using the averaging method for WTQ greater than WHP.

Torque is no longer a part of the GTS equation and hasn't been since 2014.

 

1% isn't enough, I'd be okay with a 2% or even 3% allowed variance, with a 4 HP allowance for cars that make less than 200WHP.

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If the purpose of the rule is to allow a small variance for compliance, why limit it to the first trip on the dyno? I'm no dyno expert, but I've seen 4HP+ variances amongst pulls in the same session - let alone a day or more apart.

 

As worded, I say "No" to this proposed rules change.

 

Cheers,

-jerry

 

GTS3

Western Region

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NO the current proposal of 1% - not enough allowance for all the variability we have seen with dyno runs.

 

Yes for something similar to the following:

Avg HP Allowance = max(4, 2% * dyno run with highest avg hp)

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+1 on this. I also think there should be some language that protects from people who do this consistently on every dyno (e.g., you get a one time "overage" each season)

 

If the percentage is 2% or higher: YES

The proposed rule of 1%: NO

 

EDIT: It should not be a 1 time allowance. Dynos change over time with weather and operator error.

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For. I posted the same thing last year but at 2%. 1% is way too small, 2% might even be too small.

 

I'd want to see what the variance was on the compliance dynos at VIR where all three runs were run back to back basically rolling starts. Based on what we saw, I doubt many of the three pulls were within 1% even though they were run over a ~3 min span. How can we be held to a higher standard than what the dynos will measure?

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No.

 

I have a Mustang dyno at my shop and I can tell you with 100% certainty that they will read more than 1% different on any given pull. There are too many variables and chassis dyno's have historically never been super accurate. They are a tool for tuning and doing diagnosis, reading HP and TQ is essentially a by-product.

 

The 4hp window in my opinion is too low anyway.

 

-Ryan

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Just some additional data from East Coast Champs. We were compliance dyno'd (three pulls) on Friday and Sunday on the MCE dyno. The variance between the three pulls was 1.97% on Friday and 2.92% on Sunday. Each pull was taken within 60 sec of the previous one. No change in tune between Friday and Sunday and obviously no change in tune between the three pulls in each compliance check.

 

A dynojet may be able to hold to 1% variance in a lab under controlled conditions but no way in the paddock. Their are way too many variables to control pull to pull much less between different cars. Things like water/oil/trans/diff temp, tire pressure, tire location on drum, tire temp, strap tension, yada^3.

 

We are racers can't be held to a higher standard than the measurement method is capable of.

 

I do agree it should be percentage based rather than fixed, but 1% is way too tight. Based on our data, I would say 3%. If MCE still has the data on their PC, we should get it and see what the variance was on these compliance pulls to come up with a real life number.

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I say leave it.... we should all be well versed in the dyno inconsistencies, ballast up accordingly and don't let it come down to worrying if you make the hp on the dyno...

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Against. While dynos at events have been shown to be inconsistent, the same inconsistency applies to all competitors. With that said, 1% truly is too small of a window for this proposal and, as such, I am against it.

 

On the same topic, and submitted by another GTS competitor, where are we on scales, weighing, and a common, repeatable methodology for ensuring that the scales are calibrated correctly at each event, every day?

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John,

 

The calibration of scales falls under general NASA tech and regulated by CCR, so another proposal you asked about was re-directed to people in charge of that (not GTS).

 

Dyno calculations are class specific though.

 

The reason for proposal to switch from fixed HP to % was exactly driven by the fact that with 4 HP fixed across all classes - it carries unequal values considering the difference in weigh allowance it translates too. The actual number (1%, 2%,...,10 %) is also for discussion.

 

Michael G.

GTS Nat. Dir.

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John,

 

The calibration of scales falls under general NASA tech and regulated by CCR, so another proposal you asked about was re-directed to people in charge of that (not GTS).

 

 

Thank you Michael!

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By the way, wanted to point as well, that other classes do not have a variance factor - it is all left to the discretion of the competitor - what to claim and how much cushion to have for the dyno and scales...

 

Michael G.

GTS Nat. Dir.

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