Proposed Rule Change - Dyno Allowance as a Percentage

[JSG1901]

I think the 4hp is plenty. I dynoed my car several times this year, in temperatures ranging from the high 40s to 90-degrees or so and every one of my sessions was within about 1hp of the others.

 

In answer to the early dynoing question, I have several times at Mid-Ohio been able to dyno on the Friday preceding the weekend (when we were there practicing) and/or early Saturday. Dyno sheets have not been required for practice or warm-up sessions, only for qualifying and races.

[HungOut2Dry]

Wow, not wasting anytime with the rule changes. lol

 

"Did anyone check with Dynojet?" In case you don't remember, it took a long time and several years of fine tuning the rules. I talked with three dyno makers, I have hundreds of dyno sheets worth of real data. The rule wasn't just pulled out of a hat.

 

Can someone tell me why this is on the table? I wasn't aware that the 4 HP allowance wasn't working. In fact, I only know of incidents where it worked perfectly.

 

But who am I to say....have fun with the rules.

[cstreit911]

A percentage is much more fair than a hard HP number. But of course now drivers that are right on the power-to-weight bubble can fudge their HP numbers down by a few HP so that they can run lighter. It just becomes a numbers game, but if they're dynoe'd at the track, they have to be within tolerance, and the're now NO excuse of dyno/weather/BS variables.

 

Maxx, actually this isn't true. You declare a dyno number. That number establishes your minimum weight. IF THAT MIN WEIGHT IS NOT MET, there is no exception, variance or not. IE, at that point your pwr/wgt becomes irrelevant.

 

Regarding a percentage, I think this needs to be studied based on the way the dyno's work. Are they typically off by a percentage, or a flat rate? I understand the concept and even thought about this myself, but it allows the higher HP classes quite a bit more "fudge factor that I'm not sure is necessary". FWIW I run a GTS-4 car (with carbs no less) and my HP numbers varied by ONE HP in the last two years.

[scottbm3]

Wow, not wasting anytime with the rule changes. lol

 

"Did anyone check with Dynojet?" In case you don't remember, it took a long time and several years of fine tuning the rules. I talked with three dyno makers, I have hundreds of dyno sheets worth of real data. The rule wasn't just pulled out of a hat.

 

Can someone tell me why this is on the table? I wasn't aware that the 4 HP allowance wasn't working. In fact, I only know of incidents where it worked perfectly.

 

But who am I to say....have fun with the rules.

 

Someone did and here's what they said:

 

Well, the time required to get a response from Dynojet wasn't much. I recieved the following:

 

Hello Dave,

 

 

 

I have talked to a number of guys in NASA, American Iron Series and other various forms of Spec class racing over the years about this same question and it is a very valid question when trying to make sure the playing field is as level as possible. One of the best things about using Dynojet dynamometers is the fact that they are not only repeatable but extremely consistent from one dyno to the next. Because of our manufacturing techniques and minimum amount of mathematical variables, Dynojet dynamometers will typically be within ½ hp of each other which is an industry standard. Almost always, the noted “difference” between one dyno and the next isn’t the dyno, but a host of other factors that must be carefully noted when comparability is paramount. We need to look at the correction factor with each dyno run and make sure it is similar to other runs we are comparing to. Also, we must look at the single largest factor as far as repeatability goes which is….THE CAR. Does power fall off as it gets hotter? Is the cooling system adequate? Are the runs being done in the same manner each time? Have there been gearing changes? All of these things can and will affect your numbers yet sometimes they go on forgotten.

 

I could literally go on for pages going over all the possibilities etc. however I will attach a document for you that explains it much better. Feel free to check it out and share with other racers and let us know if you still have any questions.

 

 

 

Thanks,

 

 

 

Christopher Olson

 

Dynojet Research Inc.

 

 

I uploaded the document he attached. Please right click, save as: http://fmjmotorsports.com/link/Truth_Lies_Dyno%20Runs_Final.pdf

 

 

-Scott B.

[ianacole]

Can someone tell me why this is on the table? I wasn't aware that the 4 HP allowance wasn't working. In fact, I only know of incidents where it worked perfectly.

 

The reason this is out for open discussion is because a competitor asked for it: viewtopic.php?p=171866#p171866

[dillehayd]

Wow, not wasting anytime with the rule changes. lol

 

Funny, I got an email from Mark Barr whining about the GT3 Cup car proposal, but not this one. Did I miss an email or...wait...isn't this being discussed on his forum too?

 

"Did anyone check with Dynojet?" In case you don't remember, it took a long time and several years of fine tuning the rules. I talked with three dyno makers, I have hundreds of dyno sheets worth of real data. The rule wasn't just pulled out of a hat.

 

Yes. I did. I included the response I got in this thread. Did you read the thread?

 

Can someone tell me why this is on the table? I wasn't aware that the 4 HP allowance wasn't working. In fact, I only know of incidents where it worked perfectly.

 

Because some people felt it didn't work at Nationals?

 

But who am I to say....

All racers have been invited to comment, so at very least that is "who you are to say".

[911.racer]

Ok, I thought this would be more about the 4% rule change vs talk about the rules themselves.

 

I read the dynojet info and I can see how they can say that their equipment can be within 1/2 a Hp, but what about our cars. Like they say, it can run differently if they get hot or if something is changing that we do not know about.

 

Is it fair that a 100Hp car gets a 4Hp variance as does a 500Hp car. Seems to me that the largest variable would be the car, not the dynojet unit.

 

Here is my point. We do a dyno run, we turn in those sheets. That exact number is used to calculate our weight and max Hp. If we go over the Hp that we made at the beginning of the year (or if another rule is put in place maybe a few years) then we are in trouble.

 

Why not allow us to claim more than the dyno sheet we turn in. If I make 230Hp on the dyno, why can I not say that I am making 235Hp. That way if I make 236 on the dyno at the track I am not out. It would be my choice.

 

I think that a % is better than an across the board number.

 

Ed Baus

Porsche 911

[Eric W.]

 

Why not allow us to claim more than the dyno sheet we turn in. If I make 230Hp on the dyno, why can I not say that I am making 235Hp. That way if I make 236 on the dyno at the track I am not out. It would be my choice.

 

I think that a % is better than an across the board number.

 

Ed Baus

Porsche 911

 

Ed, I think you can do that now. Just add more weight. That way when you get dyno'd and come in high, as long as you made impound weight for whatever you dyno'd at, then you'll be fine.

 

Also, where did this 4% number come in from? We never did set that as the goal... currently it is 4rwhp. Most of GTS2 is over 200rwhp right? That'd mean about 2%. GTS3 cars are all around 250rwhp (1.6%) and GTS4 cars are 300rwhp? (1.3%).

 

If we set it to 2%, that would mean GTS2 remains pretty much unchanged. GTS3 gets 1rwhp, GTS4 gets 2rwhp and so on. You could bump it up another % maybe, but youre talkin only 1-2rwhp here. Not 5-10.

 

That, as Ed is arguing, would take into account variances within our own cars. Tire pressures, tire heat cycles, coolant temps, air temps, etc etc.

 

And I know of two people getting DQd by the dyno in one weekend (Tillinghast and Myself). And both of us arent cheaters... ok ok, maybe I was cheating

[911.racer]

 

Ed, I think you can do that now. Just add more weight. That way when you get dyno'd and come in high, as long as you made impound weight for whatever you dyno'd at, then you'll be fine.

 

Eric. I did not know that. I have not been in that situation. Good to know.

 

So, with that revelation, why do we need any 'fudge factor' Everyone can decide for themselves how safe they want to be.

 

Although, if we are going to have a fudge factor, then it seems to me that Erics numbers work for me.

 

Ed

[Lemming]

IMO the 4hp rule is fine, if your a worried about making your wt/hp, then add weight, it's that simple.

[JSG1901]

Let's remember: The 4hp rule DOES NOT say you can't be more than 4hp over your claimed power. What it says is the first 4hp don't count against you.

 

My car makes 197hp. If I dyno at 207hp, 10hp too high, I have to make sure I have enough weight on the car for 10 - 4 = 6 extra horsepower.

 

And, yes, Ed, if your car makes 275hp and you want to be on the record for 290hp, you should be (and are) allowed to do that.

[116svvh]

If there is any change to the "allowance" rule, I say do away with it altogether. What is the rational for it? The racer should account for variances and compensate accordingly. If the dyno is running high for one it should be running high for all.

[Eric W.]

If there is any change to the "allowance" rule, I say do away with it altogether. What is the rational for it? The racer should account for variances and compensate accordingly. If the dyno is running high for one it should be running high for all.

 

Yes, but not everyone gets impounded.

[ELEPHANT1]

I had brought up this topic a couple times but I guess I'd not thought it through enough before doing so. One of the biggest things to be concerned about from one region to another is operator error...this I'm certain is by far the biggest error factor. In this case it should be up to NASA or the region to make sure their certified dynos are correctly run. Competitors should not be responsible for this, there is no way for us to control it.

 

As for the variance number, of course with any measurement device there will be some variance but it is NEVER linear across the measurement range. So for a dyno setting a percentage attempts to linearize it....this is not correct plain and simple. But Dynojet more or less already said this.

 

If we want to put the variance as a percentage then we need to know the amount of error across the measurement range and use that. We cannot simply apply a straight percentage across the board. When I brought this up before I can't believe I was even thinking that way. Oh well.

 

Cheers.

[ianacole]

If one car is over because of dyno variance at a specific dyno (say at the track) wouldn't all of them be over the same amount, give or take, at the same dyno?

[Eric W.]

If one car is over because of dyno variance at a specific dyno (say at the track) wouldn't all of them be over the same amount, give or take, at the same dyno?

 

Yes, but unless you get ALL the other cars onto the dyno, they'll still be going w/ their old numbers.

[ELEPHANT1]

If one car is over because of dyno variance at a specific dyno (say at the track) wouldn't all of them be over the same amount, give or take, at the same dyno?

 

Sure as heck should be, the dyno doesn't know one car from another. Same with scales!

[ianacole]

If you impound the top 3, and 2 are within the allowance and 1 isn't, I wouldn't be suspicious of the dyno. If all three are outside, then the Director has a decision to make.

[ELEPHANT1]

I think we have to be careful here and really understand what we are doing before changing the exception. 4 HP is not really that small. In most GTS2 cars that would amount to nearly a 2% variance. I think we need to understand the dynamics behind this decision including whether there is a linear relationship to variance as Hp increases. Let's not take this one lightly without the correct research.

 

Brad

 

Ok, maybe a % isnt as good an idea. Maybe a # depending on class? All I know is... before a MidO event, I dyno'd locally at 251rwhp. I goto MidOhio and I get 263rwhp. Then I come home and redyno and got 256rwhp. Then goto another dyno and read 253rwhp. A couple events later at Summit Point, I get 264rwhp. And then at another Summit event, I get 266rwhp.

 

That was with NO changes to the car at all. I saw a 12rwhp swing depending on dyno. If I had prepped even within 4rwhp or hell, even to be safe 8rwhp, I still would have been DQd. One could prep their car to be legal, but on any given day and on any given dyno, you could see a swing of anywhere up to or over 15rwhp (or 165lbs for GTS3)! That's just crazy!

 

Then, lets not even get into scale variance. For this last NJMP event, I put my metal trunk/hood back on and somehow I weighed in less than when I had the light CF parts in!

 

And THEN... what are the rules regarding impound dyno? At NJMP I was told if impounded, we had to PAY for our dyno?? Somehow I find that to be not right.

 

Again, I think the real problem here is the dyno operation, not actual dyno variance. Well, I'm assuming of course that proper maintenance and calibration certs are up to date, that alone might be a big assumption. I think NASA National/Regions need to make sure the dynos that we must comply with are correctly operated and calibrated.

 

I think writing the rules around this type of variance only leaves the door open to potential future issues.

 

Cheers.

[ELEPHANT1]

If one car is over because of dyno variance at a specific dyno (say at the track) wouldn't all of them be over the same amount, give or take, at the same dyno?

 

Yes, but unless you get ALL the other cars onto the dyno, they'll still be going w/ their old numbers.

 

Yeah, of course this assumes that at least some of the cars will have previous dyno numbers as well as at that event numbers...such that they would at least know. The director should be checking this to make sure there is not some large swing from what a competitor used to have and what they have now. This can get dicey but it needs to be watched.

 

Cheers.

[Keith Andrews]

My .02 are a variance of, 5hp or 2% whichever is greater. That's coming from an under 200 hp car .

[Eric W.]

If one car is over because of dyno variance at a specific dyno (say at the track) wouldn't all of them be over the same amount, give or take, at the same dyno?

 

Yes, but unless you get ALL the other cars onto the dyno, they'll still be going w/ their old numbers.

 

Yeah, of course this assumes that at least some of the cars will have previous dyno numbers as well as at that event numbers...such that they would at least know. The director should be checking this to make sure there is not some large swing from what a competitor used to have and what they have now. This can get dicey but it needs to be watched.

 

Cheers.

 

The only time I ever saw something like this happen... was when both me and Tillinghast both read 10 high. Granted the weather was cooler... but 12HP is a lot. I think that weekend I even put in extra weight, but still came out with too much power on the dyno to avoid DQ.

[JoeMag]

I'm in favor of a % change vs a fixed number.

[911.racer]

I'm in favor of a % change vs a fixed number.

 

 

I was, but now I am not. The 4Hp should be for the dyno, not the car. If the variation of error of the dyno is linear, then it should be a static number, not a percentage.

 

If you think your car is running strong one day, add weight.

 

Ed Baus

[Trackrocket]

In using "idiot logic" or "linear logic" - doesn't matter...I'd much more favor a % than a hard # as it makes sense for the higher HP cars.

 

Personally, I don't think it's fair to allow an E30 or a 944 4hp and then a Twin-Turbo'd freak of a 911 4hp...as I have seen too much of a dyno variance...one of the reasons why I'm giving up GTS2 and jumping to GTS3...my car's HP was too close, ALL the time...and when I pulled a considerable amount more HP on the dyno at the Nationals last Fall when compared to Fall of '07, I had enough.

 

For the guys that say their dynos vary by 1hp...to me, that's crazy and hard to believe...but I DO believe you...for argument's sake...but mine has varied a good 6 or more HP, but generally varies around 3-4 HP...ON THE SAME DYNO.

 

The Nationals dyno was just a shocker to me...for those of you who paddocked around me last Fall, you know how upset this made me, but I apparently didn't have the rule clear in my head - Mark had to inform me that I was "OK" and in compliance although I was certain I wasn't.

 

I had the "4hp forgiveness" all wrong.

 

Anyway, I would be in favor of a 2.5-3% rule ...in my case, this would allow for 6.25-7.5hp as with a chip and headers I'm about 250hp now...so I'm thinking more like 2.5% or lower would be appropriate??

 

There's my vote...regardless of how someone runs their racing setup with respect to weight/HP and whether they're being honest, fair or smart and running more weight than necessary to compensate for possible variance...I think a % rule is more fair and please keep in mind the "spirit" of this rule is to protect the honest, not the guys who are pushing it...like I did for 4 years.