Rule Change Proposal: Section 6 Dyno Requirement

[ianacole]

Proposed change from:

 

Competitors may use any brand of dyno for certification, but all compliance runs at events will be made on a Dynojet Model 248, 224, or 424 in SAE mode with a smoothing factor of 4 so it is highly recommended to use one of those dynos with those settings for certification to avoid any errors in classification.

 

to:

 

Competitors must use a Dynojet brand model for compliance as compliance testing at events will be made on a Dynojet Model 248, 224, or 424 in SAE mode with a smoothing factor of 5

[Lemming]

I pushed for this one last year, glad to see it back. Without standardizing the certification dyno, there is no reason to even do the certification.

[JSG1901]

 

I think we have to do this. From other recent discussions in this forum it is clear that very few regions regularly--if ever--have dynos at the track. I've always raced with Great Lakes and we have always had dynos at half our events or so, so I assumed everyone did. Apparently that's not the case.

 

As the GL GTS Series Director I have seen dyno sheets from a range of dynos. Most, thankfully, were DynoJet and have proven to consistently come in very close to what we test at the track. At the other end of the scale are Mustang dynos which we find to be 15-20% low as compared to the DynoJet.

 

Let me put that into numbers:

 

A typical GTS3 car makes about 260hp. At 260hp that car would need to weigh 2,860 lbs on DOT tires. If, however, it had been tested on a Mustang, it would most likely have been rated at something in the 216-226hp range, meaning a minimum weight of 2,376-2,486 lb. Depending on which of those numbers you choose to use, that is a "legal" reduction in weight of from 374 to 484 lbs. My most recent experience with Mustang numbers saw a 21% discrepency from the DynoJet value which, in this example, would be a minimum weight reduced by 496 lbs.

 

When I took 250 lbs out of my own GTS2 car several years ago, that change alone was good for an improvement of 1.5 to 2.0 seconds a lap at Mid-Ohio. A 500 lb reduction would likely be double that, meaning just by virtue of the dyno results--and by following the current rules--drivers using Mustang numbers could have a significant advantage on the track, whether intentionally or not, which will most likely go undetected given the lack of dynos at most regions' events.

 

Other dynos read differently than DynoJets, too, of course, but I'm using Mustang as an example here because it is the most different--and in the worst way--in my experience.

 

Very few of our GL racers provide dyno sheets that aren't from DynoJets, so changing this rule will actually effect very few of my drivers. I think that given the current state of affairs with regard to the lack of dynos at tracks around the country this is the only reasonable approach to take.

 

Vote YES to require only DynoJet dyno sheets for GTS.

 

[John Graber]

Might need to expand the wording even more to elaborate on the set-up when testing. Check-out the AI forums and the issues with the dyno adjustments at the Championships.

[RSCoupe]

I had to vote no, just like last year, as AWD Dynojet dynos are few and far between (2 in Chicago area), and can be very difficult to get time on if you're not a customer of the shop.

[Snymo]

I can see both sides to this one. It would be nice to have consistency across the regions for dyno testing but I agree with Mark that AWD Dynojets might be hard to find. We are lucky to have one easily accessible in Denver, but other locations might be different. Not to muddy the waters further but the NASA TT rules offer what might be a decent middle of the road option:

 

"...dynamometer tests must be conducted on a Dynojet Model 248 or 224 for front and rear wheel drive vehicles, and on a Dynojet, Mustang, Dyno Dynamics, or Dynapack for AWD cars, in a commercial facility that offers dynamometer testing as part of their business and is open to the public. All Dyno test results using a Mustang dynamometer will have 10% added to the maximum horsepower reading to obtain the...weight/power ratio (Mustang Dyno awhp x 1.1 = Maximum awhp for wt/hp calculation)."

[JSG1901]

I can see both sides to this one. It would be nice to have consistency across the regions for dyno testing but I agree with Mark that AWD Dynojets might be hard to find. We are lucky to have one easily accessible in Denver, but other locations might be different. Not to muddy the waters further but the NASA TT rules offer what might be a decent middle of the road option:

 

"...dynamometer tests must be conducted on a Dynojet Model 248 or 224 for front and rear wheel drive vehicles, and on a Dynojet, Mustang, Dyno Dynamics, or Dynapack for AWD cars, in a commercial facility that offers dynamometer testing as part of their business and is open to the public. All Dyno test results using a Mustang dynamometer will have 10% added to the maximum horsepower reading to obtain the...weight/power ratio (Mustang Dyno awhp x 1.1 = Maximum awhp for wt/hp calculation)."

Two problems here. First, 10% is not even close to the difference we have seen between Mustang and DynoJet dynos. If there were a 20% factor applied, I would reconsider my position on this.

 

Second, the GTS rules currently say you MUST do compliance on a DynoJet. Given how hard Mark and others say it is to get on a DynoJet AWD dyno, that makes it all the less likely that NASA will be able to do compliance testing on your car if it is AWD. Our procedure for dynoing an AWD, since there will never be an AWD dyno at the track, is to seal the car and require you to take it someplace (with a DynoJet) to be tested. That means you can't even open the hood until the dyno is completed. From what people here are saying that might be weeks or longer.

 

This hasn't been an issue in GL so far because we haven't had any AWD cars that are consistently running far enough forward in the group to be a concern, but Matt Markowicz is getting faster and if Mr Siggelkow ever gets that car of his working this might be a very different situation.

 

Given that level of difficulty in determining if a vehicle is legal or not, I would argue it is all the more important that the base number--the one used to determine your minimum weight--be from a DynoJet because for all intents and purposes that is all we have to go on.

 

That or just disallow AWD cars, which I'm not advocating but which would solve the problem.

[Lemming]

I'll take the mustang and 10% dyno anytime over a dynojet reading! Of course, when I'm protested and tested on a dynojet, I'm screwed. I've seen anywhere from 13-20% difference between the two.

[Snymo]

10% is not even close to the difference we have seen between Mustang and DynoJet dynos. If there were a 20% factor applied, I would reconsider my position on this.

I've seen anywhere from 13-20% difference between the two.

 

Didn't realize there was such a big difference....nevermind then.

[John Graber]

since there will never be an AWD dyno at the track

In 2008 at the Nasa Championships at Mid Ohio we had an all-wheel drive dyno. We used it several times for compliance testing in TT & PT. In 2007 we had a PT car sealed and transported to an AWD dyno in the Cleveland area for compliance testing after the event. It can be done, but certainly allows for a much more difficult compliance testing, especially for an individual region.

[Eric W.]

 

Given that level of difficulty in determining if a vehicle is legal or not, I would argue it is all the more important that the base number--the one used to determine your minimum weight--be from a DynoJet because for all intents and purposes that is all we have to go on.

 

That or just disallow AWD cars, which I'm not advocating but which would solve the problem.

 

I agree w/ Scott here. Because of the fact that AWD dynos arent prevelant, and after race impounds probably wont happen, it is critical that the submitted number be the same used for everyone else. Granted, that doesnt stop someone from cheating on the AWD dyno and submitting a false sheet, but that will have to be taken care of w/ the sealed protest/impound procedure I suppose.

 

These dynos are required once per year. I understand the burdon of finding one and it may be far, but it is ONCE in 12 months. Just my opinion....

[EdP]

In my view, a better short term goal (than requiring use of a Dynojet) would be getting more racers to test on the trackside dyno that will be used for compliance. Using the same dyno would produce much more consistent and predictable results. I know it's impractical to make that a firm requirement, but it ought to be strongly encouraged.

 

Will NASA definitely being using dynos next year for compliance? I've read and heard that the use of a GPS-based system was being explored. To me, that would be a giant step forward for the series if it could be successfully deployed.

[claykos]

I just thought I should chime in with my recent experience on a mustang dyno - my impression from the way the dyno was operated is it could basically be made to spit out any number you wanted depending on how the operator calibrated it (which to a great extent is true on every dyno, but the calibration procedure seemed extremely arbitrary on the mustang)

 

I will also say that I dynoed 2 cars on this mustang dyno, both of which had been dynoed on a dyno jet before. One car made ~350 rwhp on a dyno jet and it made ~360 on the mustang. The other car had made 238 rwhp on a dynojet and made 260 rwhp on the Mustang....

[jakermc]

We've had cars come in from out of state with Mustang dynos and when they retest here on a Dynojet hp has jumped in the 20%+ range. I would support only using the Dynojet.

[Lemming]

I will also say that I dynoed 2 cars on this mustang dyno, both of which had been dynoed on a dyno jet before. One car made ~350 rwhp on a dyno jet and it made ~360 on the mustang. The other car had made 238 rwhp on a dynojet and made 260 rwhp on the Mustang....

 

Do you have the numbers backwards, I've never seen mustang numbers greater than dynojet?

[KTL]

Ask Roy Lipner what he experienced- Mustang came in higher. When he dynoed on the mobile Dynojet at Putnam, he came up around 20hp lower than expected. No fall-off in performance of the car either.

[John Graber]

I came in way low on the dyno at Putnam as well after Saturdays qualifying.

5.6% low on HP

7.8% low on Tq

[JSG1901]

I came in way low on the dyno at Putnam as well after Saturdays qualifying.

5.6% low on HP

7.8% low on Tq

That's really interesting. According to DynoJet there is nothing the operator can do to change the way it measures power. I suppose the one exception to that is deciding whether to use the SAE correction factor or not. That's as opposed to dynos like the Mustang where there are all kinds of parameters which can be fiddled with.

[kbrew8991]

but if you do your pre-season compliance run with the car cool vs your post-race compliance run with the car still heat soaked... Sure you can't really mess with the dyno itself to produce different numbers but you can alter the numbers depending on alot of other outside factors.

[JSG1901]

Granted, but 6-8% seems like a lot.

[cwbaader]

The rule for a single make dyno is certainly a good idea. A better idea would be actual ienforcement of the rule. If the competitors have no reasonable expectation of being checked, then there is no rule. You can make a dyno run look any way you want. I have run against cars that make 90hp more than I did while weighing only 200# more. The solution is enforcement...until the rules are enforced, there is no rule. Chuck