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JSG1901

2015 GTS Rules changes

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7VO-VOM
What is a great surprise to me is how transparent and polarized the posts about this change are. I actually did not think that the flat tune offered that much advantage, but now that I am seeing everyone trying so hard to preserve it, maybe I am wrong. Maybe this change should have taken place years ago.
You are reading into the responses a bit too far. In the interest of saving some money on my build, I wasn't going to tune my car, at least for 2015. I'd run a restrictor and/or more weight if it dyno'd too high, and lose more weight if it dyno'd too low. I know that the people who detuned/flat tuned their cars will be retuning, plus more people will tune as their upgrade for this year. Seeing how easy it would be to get around the new rule for a big advantage, I feel I need to spend the money on dyno time and tuning to keep up. Alternatively, if I had not had a good past couple years at work, I'd be building an old Porsche with minimal tuning options. I would still be against the rule. I am not trying to preserve the old rule. I simply see that the new rule is poorly thought out, easily bent, and unfair. It's as simple as that.

 

I don't think this rule is to target BMWs. It is to target cars with flatter power curves which happen to be mostly BMWs because they are, for the most part, the newer engines with more easily adapted ECUs. A 928 or a 951 is just about as penalized as the BMWs due to their higher/flatter torque curves, but you don't see many of them in GTS.

 

Maybe I missed more, but I have only seen one non-director post in this thread in support of the 3rd rule change, and he openly admits that he'd rather run ST. Clearly, the majority are against it. Clearly it is flawed. We just don't know how flawed yet because it still hasn't been published 3 days after it was promised.

 

"This is the LAST year where the current power to weight formula will be used. Here is our first stab at how we think it will be for the 2016 year set of rules, and here's a sample spreadsheet to play with now, with proposed new formula. We will continue to refine and adjust this formula, and hope that within six months we can all agree on a tweeked version of this. The 2016 power to weight formula will be finalized by July 31, lets get to work and make it something we can agree on."
This is briliant! No more waiting indefinitely for a flawed rule for 2015, and you might get more positive input if it's a 'maybe' for 2016. Problem solved. Dump the change for 2015.

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cash7c3

(Not directed at you Cash)

I've heard 5 separate comments about how easy it is to "beat" the system and ruin GTS, but no one willing to share input how they think that will happen... ...and then complaining that this was done without racer input.

I'll throw out an example for a turbo car though i'd imagine you could do it with the correct motor/management/tuning/class choices n/a . From what I would do with a turbo motor I'm currently building for GTS5 and similar power/weight classes top 30% is above 5125 rpm. With some simple boost control and intake restrictors it shouldn't be difficult to make (average) gts3/4+ horsepower from 3k-5k rpm take all the boost out at 5k and make gts2/3 power in the top 30% of the range that the new rule specifies. This would effectively give me gts3+ hp in gts2 or gts4+ hp in gts3. I'd just have to drive a different rpm range than typical.

 

This is with something not built to maximize the rules. I could pretty easily raise the rev limit to around 8k to give me more room to work with, and with a couple more motor parts I'd feel pretty comfortable with a 9k limit, both which would give more room to work with higher gains. Throw in a correct turbo and cam choice to beat these rules for more gains, etc, etc.

 

I'm more likely to just drop the series entirely than bother much maximizing the new rule set, but I may throw a half ass setup on track for a weekend to prove a point.

 

...I continue to chaff at the accusations from various people that the old rules were unfair to anyone.

 

I do not recall any part of the rules that prohibited people from using very common and relatively affordable tuning options for their own engines to maximize their car prep to the given set of rules.

 

The old rule set was easy to enforce, it was easy to calculate power, and ANYone could reasonably tune their car to meet those guidelines if they chose to. To NOT choose to is lazy and leaving power on the table for that set of rules.

 

...It is as patently ridiculous to say that people should be able to race their engines the way they came from the factory, and therefore we need a better way to measure power, as it is to suggest that people race their cars with the weight as they came from the factory when this is a classed system with power to weight as the criteria.

 

What I read between the lines is:

 

"I spent a fortune on my car. It has a great engine out of the box. I need the rules to have a more accurate way to measure power so I don't have to adjust my engine's performance and be at a disadvantage vs people that will tune their engines to maximize their car prep. I can't be bothered with that."

 

...I'm not unsympathetic to the Director's plight. I grant that there are better ways to measure power. But before I would publish that "this is how we're going to do it", I would make sure I had the recipe ready, and that it met the criteria of reproducibility, simplicity, and lacked any operator bias in how the results were achieved. I don't see how you guys are going to pull that rabbit out of this hat with whats been described.

 

And.... since I hate whiners that don't have constructive advice to problem solve......

 

Here's a concrete suggestion for GTS: With such a massive change being contemplated, it makes much more sense at the 11th hour to make a public statement like this:

 

"This is the LAST year where the current power to weight formula will be used. Here is our first stab at how we think it will be for the 2016 year set of rules, and here's a sample spreadsheet to play with now, with proposed new formula. We will continue to refine and adjust this formula, and hope that within six months we can all agree on a tweeked version of this. The 2016 power to weight formula will be finalized by July 31, lets get to work and make it something we can agree on."

 

Everything here is spot on imo and I agree 100%

 

This new ruleset looks to me like a knee jerk reaction to people complaining because they have decided what class their car belongs in, got out-developed or spent, and are unable to accept that they need to detune and drop to a lower class or continue developing their platform to be technologically competitive.

Edited by Guest

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Michael G.
Show me the actual advantage to the flat tune. Real proof. Not a dyno graph or line. Not speculation. Show me video, data, anything real.

 

Josh,

 

You are a very fast and talented driver in any car, even in the old 911 years ago with no tune. It is difficult to show a visual proof, like video, since there are too many variables, driver's skill would be the main one. My argument would be that the average under the curve would be a better way to measure it, since that is where the car is driven most of the time - not at the peak, which reached only for a short time infrequently. Isn't that the case? Why do you think the peak number is better?

 

Michael G.

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J Smith
Josh,

 

You are a very fast and talented driver in any car, even in the old 911 years ago with no tune. It is difficult to show a visual proof, like video, since there are too many variables, driver's skill would be the main one. My argument would be that the average under the curve would be a better way to measure it, since that is where the car is driven most of the time - not at the peak, which reached only for a short time infrequently. Isn't that the case? Why do you think the peak number is better?

 

Michael G.

 

Thanks. But actually, I got my ass kicked regularly in my 911. You want to know why? Because it was a crappy car for the class. Mike Skeen wouldn't have been able to win in that car (well, maybe that's debatable ) So guess what I did? I bought and built a car specifically for GTS3. Because that's what you do in racing...you give yourself the best chance at winning with the resources you have and do it within the rules. You know what else is crazy, I raced my E46 for a year with no detune whatsoever. And I won. A lot. Track records and good stuff like that. But the car was incredibly heavy, and was hard on tires and brakes and just felt like a cow to me. So guess what I did? I stripped out over 200lbs and detuned. And you know what...I went SLOWER!! Who would have thought it??!! Sure, I eventually got faster again, but most of that was due to installing better shocks, aero and brakes. I still think that car would have been faster at 300hp/3300lbs, but tires just wouldn't last at that weight...especially a 45min national championship race (which was the ultimate goal). Open rule set gave me the option to prepare the vehicle where I thought it would work best. A detune was part of that. So why will that one part of a car build be penalized now?

 

I don't know what is the best way to measure hp. There probably is a better way that what we do now, but no one seems to have a solid grasp on that just yet. This rule is being rushed/forced down our throats and it feels wrong.

What I do know is that I haven't seen a reason to change the current rule set (yet). The proof of massive acceleration differences just isn't there between differently tuned vehicles.

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Try this on for size:

 

Old rule set: Quite simply up and down the line EVERYONE could reasonably tune their car to more or less take advantage of the rules and build a competitive Dyno curve. They could take new or old engines with high or low redlines, and through tuning, get a flattish curve to maximize the HP available at all racing rpm for their weight.

 

On the flipside now, you either start with an engine that spins to 9000 and gives you 3000 rpm to play with, which is so clearly the type of engine you want if you're building to this new set of rules, or you build it.

 

To build this for the vast majority of engines out there will require serious rebuilds, head work, cams, pistons, possibly lifters, AND tuning on top of that, and the result is a short lived engine and great expense.

 

To be clear: The question really should not be which formula measures different curves more accurately, it should be what rule set is most easily maximized by the most people.

 

Do you want to cater to high strung, high rpm engines that have cams, lifters, pistons, intakes, headers and such designed to rev to 9000 with ever increasing HP as rpm climb?

 

It's ok, but call it like it is, and admit that is what's going on.

 

In 2014 ANYONE could tune their engine by slapping on standalone if needed and build a car with more

less as much hp as possible in their racing rpm without having to do THAT much.

 

Now, to maximize their cars they will need an engine that spins to 9k.

 

I think this is a big deal.

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Michael G.

But the argument here that you may not need to build a high revving engine, since with your average one you will get a lower HP value and lower minimum weight. Another argument from the other side is that there is little advantage in building this special engine to begin with.

Again, you can choose to build whatever you want, but the issue here is which HP value is better representing the working capability of the engine and all major tuners, Data Logging experts agree that it is and average under the curve vs peak.

 

Michael G.

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JVR127

Or you can just spend 15k in a sequential box and tune the motor to use ONLY 2-3 rpm range... Have first gear go to 70mph and split the rest.. What do you do about that? Penalize the sequential box more because they spent the money to tune and maximize their car?

 

If this is about keeping it competitive and you wanna penalize the guys that are winning all the time then do something else... Rewards weight comes to mind which is used in many professional series and it would keep things interesting and everyone will have a chance.

 

the way this is being done everyone is being penalize one way or another so in essence the guys that were finishing 5th and below will still be finishing there... Why? Cause they didn't want to spend the time and money to maximized their cars before so what's gonna change now? Nothing cause they still won't spend the time to do it.

 

The focusing on this detuned cars is absurd, front running guys have spent more money and time developing suspension, aero and brakes and that's why they are fast all the time.... Explain to me why is it that theirs plenty of detune cars that are not running up front? Why cause they thought that's all it took.

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Michael G.

Jonathan,

 

You might be surprised to know that the whole issue of the Rule change was discussed only as a tool for better measuring HP and was not brought by de-tuned cars or by cars winning or loosing. It was a continuous discussion on the matter that was going on for years. I am not sure why this thread keep being shifted into this. If you think that the equalizing formula is to be discussed - that might be in order as well.

And it is true - most winning drivers develop other components like aero, brakes and suspension and skills - all of which are completely open and not measured. Are you suggesting to limit or penalize those too?

 

Michael G.

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But the argument here that you may not need to build a high revving engine, since with your average one you will get a lower HP value and lower minimum weight. Another argument from the other side is that there is little advantage in building this special engine to begin with.

Again, you can choose to build whatever you want, but the issue here is which HP value is better representing the working capability of the engine and all major tuners, Data Logging experts agree that it is and average under the curve vs peak.

 

Michael G.

 

No, no, and no.

 

A high rpm engine will have a larger rpm range to play with when you look at 30% of the total. Take 9000, and you can use 3000 rpm. With these high rpm engines, the slope of hp is rising quickly. A CR gearbox and diff is all that is needed to ensure that the 9K car only shifts in a 2000 rpm range, the highest of the 3000 "graded"

 

A car with 6700 redline will have ONLY 2000 rpm to be graded, ALL of it may average to the same as the 9k car, but it must use all 2000 rpm for its cr and diff.

 

CLEARLY these two cars will weigh the same, and will have the same power rating. NOTHING will substitute for the high rpm engine with these rules.

 

I dunno, sounds much like displacement racing to me, exactly what I ran away from in BMW CR.

 

There is a massive slight of hand going on here....

 

Problem: "We don't want to have to tune our engines"

 

Answer: "Lets put forth an argument that the current methods don't accurately describe a dyno curve, and maybe the ignorant will not realize that this is not the point, but since we all know that the best race motors are the ones that make the most torque for the longest rpm, we can keep ours as they came from the factory, and not have to change anything. Pity the fools that don't have race motors, they can just build one AND tune it, or buy a more race like motor with high rpm and transplant it."

 

Frankly I liked the old rule set where, as I said, virtually ANYone could maximize their power for a given rpm with ONLY tuning, and not have to own, or build a high strung, high redline engine... they could take a commuter engine and be on an even footing with a detuned race like engine.

 

It is easy to agree that there may be a better way to measure a given HP curve. But why are we focused on that when the curve is part of what racers can and do change at will to maximize their placement within power/weight classes?

 

The real problem I see here is that the hot set up before could be a wide variety of engines... now it will be a small subset of what is made.... S54, S65 and GT3 9000 redline engines.... That is a shame.

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Michael G.
A high rpm engine will have a larger rpm range to play with when you look at 30% of the total. Take 9000, and you can use 3000 rpm. With these high rpm engines, the slope of hp is rising quickly. A CR gearbox and diff is all that is needed to ensure that the 9K car only shifts in a 2000 rpm range, the highest of the 3000 "graded"

 

Thanks for sharing the scenario. I wonder what would be the answer to the above set up under current rules - seems like this would be a winning package regardless of how do you measure HP.

 

Michael G.

NE GTS Dir.

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A high rpm engine will have a larger rpm range to play with when you look at 30% of the total. Take 9000, and you can use 3000 rpm. With these high rpm engines, the slope of hp is rising quickly. A CR gearbox and diff is all that is needed to ensure that the 9K car only shifts in a 2000 rpm range, the highest of the 3000 "graded"

 

Thanks for sharing the scenario. I wonder what would be the answer to the above set up under current rules - seems like this would be a winning package regardless of how do you measure HP.

 

Michael G.

NE GTS Dir.

 

I'm not sure what you mean by what would be the answer. To what question?

Neither set up would be optimized under our current rules given a peak Hp at just one point.

 

The lower redline car would have a lower peak Hp as described, and the higher redline car would have a higher peak Hp. If they wanted to be in the same class, they would not have the same weight, and might be competitive.

 

Potentially more balanced in the current scheme actually.

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7VO-VOM
A high rpm engine will have a larger rpm range to play with when you look at 30% of the total. Take 9000, and you can use 3000 rpm. With these high rpm engines, the slope of hp is rising quickly. A CR gearbox and diff is all that is needed to ensure that the 9K car only shifts in a 2000 rpm range, the highest of the 3000 "graded"

 

Thanks for sharing the scenario. I wonder what would be the answer to the above set up under current rules - seems like this would be a winning package regardless of how do you measure HP.

If you look at a stock E9x M3 dyno, the torque is basically flat up to 7000-7500, then it starts to drop off about 10% by redline. Peak torque is well under peak HP due to the high revs. The flat torque curve all the way up, means the HP is constantly climbing. If you look at a stock 928GTS (for V8 to V8 comparison and peak HP in the same ballpark) dyno, to get close to the same HP it has much more torque, but the torque falls off after 4000 losing ~25% by redline. That means the HP curve on the 928's M28 is much flatter than the M3's S65. Not only does the lower revving 928 have less rpm range within the 30% to play with, it's more heavily penalized by the average/area under the curve.

 

Just a rough eyeball estimate:

S65

Peak HP 362

Ave HP 325

Drop from current to proposed 10%

 

M28

Peak HP 330

Ave HP 310

Drop from current to proposed 6%

 

cid_15627521630042008-2D7E.jpg

332801d1233438431-gts-dyno-runs-stock-ish-baseline-4bfm072-2009-01-31-data.jpg

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flink

I think the proposal is a good one. I don't see a need to delay until 2016 - this change can be made at any time. Nobody will need to decrease power, nobody will need to add weight. The people who have flat power bands will not need to make any change. People who have peaky power bands will be able to add power and/or lose weight, at their leisure.

 

The one thing which I believe should be changed is the "top 30% of the rev range" thing. That's just too easy for people to play games with. This should be changed to "the rev range from N RPM to 1.43*N RPM which has the largest average power". For engines which make max power at the rev limit, this is identical to the "top 30%" concept. For engines which make max power at a lower RPM, the range will be moved lower.

 

This is trivial to do in software (eg excel) and is actually pretty easy to do by hand, if we're not going to attempt to interpolate.

 

Here's how it's done. Calculate each of the following:

 

([email protected] + [email protected]) / 2

([email protected] + [email protected]) / 2

([email protected] + [email protected] + [email protected]) / 3

([email protected] + [email protected] + [email protected]) / 3

...

([email protected] + [email protected] + [email protected] + [email protected] + [email protected]) / 5

([email protected] + [email protected] + [email protected] + [email protected] + [email protected] + [email protected]) / 6

...

 

Then take the largest number. That's your power.

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hamflex
I think the proposal is a good one. I don't see a need to delay until 2016 - this change can be made at any time. Nobody will need to decrease power, nobody will need to add weight. The people who have flat power bands will not need to make any change. People who have peaky power bands will be able to add power and/or lose weight, at their leisure.

 

The one thing which I believe should be changed is the "top 30% of the rev range" thing. That's just too easy for people to play games with. This should be changed to "the rev range from N RPM to 1.43*N RPM which has the largest average power". For engines which make max power at the rev limit, this is identical to the "top 30%" concept. For engines which make max power at a lower RPM, the range will be moved lower.

 

This is trivial to do in software (eg excel) and is actually pretty easy to do by hand, if we're not going to attempt to interpolate.

 

Here's how it's done. Calculate each of the following:

 

([email protected] + [email protected]) / 2

([email protected] + [email protected]) / 2

([email protected] + [email protected] + [email protected]) / 3

([email protected] + [email protected] + [email protected]) / 3

...

([email protected] + [email protected] + [email protected] + [email protected] + [email protected]) / 5

([email protected] + [email protected] + [email protected] + [email protected] + [email protected] + [email protected]) / 6

...

 

Then take the largest number. That's your power.

 

 

Thats the issue, its not clearly the "top 30%" the 30% comes after a series of inputs being.... hp at every 1000 rpm from upper 50% rev range of your motor, peak hp, redline, and lastly hp at red line. Now from here the "calculator" determines what the "optimal 30%" is, plots 10 points and averages them.

 

Top 30% is one thing. Optimal 30% based on a series of inputs is the million dollar question.

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J Smith
...the whole issue of the Rule change was discussed only as a tool for better measuring HP and was not brought by de-tuned cars or by cars winning or losing.

You really have to stop with the statement that the dominance of detuned cars has had nothing to do with this rule change. Scott CLEARLY states in the first post of this thread that that is the sole reason for the change (complete with dyno charts!!). Someone just needs to convince me that it is because of the detune ALONE that these cars are dominating. I have yet to see anyone offer up any real evidence that proves that.

 

...Nobody will need to decrease power, nobody will need to add weight. The people who have flat power bands will not need to make any change. People who have peaky power bands will be able to add power and/or lose weight, at their leisure.

Spin it however you want...cars with a detune will be penalized or cars who have a "standard" dyno chart will will be given an advantage. It's the same thing.

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mikew968

Much of the technical debate is over my head and I would think most of the people on this forum. But, what is clear to me is we need the formula and time to debate it or put this off a year and introduce it as a potential rule change for 2016 when it is ready.

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cstreit911
I'll throw out an example for a turbo car though i'd imagine you could do it with the correct motor/management/tuning/class choices n/a . From what I would do with a turbo motor I'm currently building for GTS5 and similar power/weight classes top 30% is above 5125 rpm. With some simple boost control and intake restrictors it shouldn't be difficult to make (average) gts3/4+ horsepower from 3k-5k rpm take all the boost out at 5k and make gts2/3 power in the top 30% of the range that the new rule specifies.

 

First the SD's didn't just fall off the turnip truck. "Top 30%" is where you are getting caught up in your shorts. Simply tuning out the last 1000 RPM or moving the power curve down to lower revs doesn't fool the algorithm. It sees that.

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7VO-VOM
I think the proposal is a good one. I don't see a need to delay until 2016 - this change can be made at any time. Nobody will need to decrease power, nobody will need to add weight. The people who have flat power bands will not need to make any change. People who have peaky power bands will be able to add power and/or lose weight, at their leisure.
Really? You might want to read the OP before supporting something and spreading bad information.
To truly level the playing field' date=' either [b']the green car (in this example) should carry a bit more weight[/b], the blue should be allowed to run a little lighter, or each should move a little each way.

 

And in essence, that’s what we are doing with the minimum weight calculations for 2015.

 

...

 

Because the resulting average horsepower values will be lower than the peak horsepower numbers we use today, the ratios for each class will be adjusted accordingly. Our goal in this adjustment is to find a balanced value for each class, where roughly half of our cars will need to add weight (or reduce average power) and about half can take weight away.

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7VO-VOM
First the SD's didn't just fall off the turnip truck. "Top 30%" is where you are getting caught up in your shorts. Simply tuning out the last 1000 RPM or moving the power curve down to lower revs doesn't fool the algorithm. It sees that.

The SD's may not have fallen off, but they are arriving in the turnip truck 3+ days late when clearly most people do not want turnips.

 

Publish the magic algorithm or can the rule change consideration until 2016. The longer it's delayed, the more you add insult to injury.

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"Top 30%" is where you are getting caught up in your shorts. Simply tuning out the last 1000 RPM or moving the power curve down to lower revs doesn't fool the algorithm. It sees that.

 

Chris,

 

Someone has to show us how a spreadsheet or computer program is going to choose a given 30% to look at for establishing the range for 10 data points to be collected.

 

The answer can not be someone at the trackside eye-balling it. (not that this has been suggested, but in absence of an algorithm, we're left with only a vague assurance that it can be done repetitively, and without bias, and somehow, actually know, or predict where the racer will actually be shifting gears and using that rpm)

 

Flattish dyno curves that are out there come in two categories.

 

First, the engines that came that way in their natural state. These are fairly common, and often found in commuter cars, but rarely in high end sports cars with high redlines.

 

Second, they are found in cars where the owners have adjusted their tune to maximize their car's potential within a power/weight class. No different than adding or subtracting weight, or tuning to get just a little more or less power to get to where they want their power/weight to be. That's racing folks

 

Here's the rub.

 

The "other" type of dyno curve, where you have quickly rising HP to maximize torque as far up into the rev range as possible, is ONLY found in a select group of engines...... These new rules are clearly going to favor them, at least as stated so far, without an actual algorithm to prove otherwise.

 

Here's a devil's advocate question to ponder.... since the OP suggested that SDs looked at how common gearboxes work with common ratios... would they be happy choosing say the highest 2000 rpm of a given dyno curve? NOT a percentage?

 

2000 rpm is a narrow enough range that you can't "game" the algorithm by just using a portion of 30% taken from a high redline engine.

 

I'd say this is a step towards taking the bias out of the new rules as high redline cars will have to use the highest 2000 rpm of their dyno curve....... which is exactly what they want to do, (but they want to be graded for power by including the lower lower 1000 rpm with less power to get a lower average power value.)

 

This is what puts low rpm cars at a disadvantage with a generic 30%.....

 

All this in the guise of "it measures power more accurately"

 

Fine, lets use 2000 rpm of the highest HP available. Use whatever algorithm you have to choose 30%, and modify it to identify the top 2000 rpm.

 

Lets see who's shorts get caught up now.

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JSG1901

Guys, I appreciate the passion here. It means that everybody cares.

 

My reluctance to publish the algorithm has simply been because we have been trying to carefully test it, and my assumption was that if we published it and decided it needed adjustment, it would start a s---storm...like we're pretty much having here anyway.

 

So here you go:

 

The big question, in my mind, has to do with what data we enter. We have code to take horsepower values from every 1000 RPM and convert it into smaller pro-rated increments between those fixed data points, and we also have code able to take the data export from the dyno and read it in. Obviously, in the long run this second approach is better for a couple of reasons. First, it eliminates the (small but) inevitable errors that come from pro-rating intermediate values. Second, it eliminates the need for keyboarding in values and the possibility of errors there.

 

On the other hand, very few of us, today, have data files for our dyno runs, which makes the second approach harder initially. Also, uploading data from trackside can be problematic, although there are ways around that. Regardless, one way or another we get data from which to start.

 

If we're reading directly from the dyno data, we have our RPM/hp points. If we are using the manually-input-every-1000-RPM approach, the code takes each of those points, inserts the max hp point where it fits, adds the redline and redline hp where they go, and then pro-rates between all these known points, generating a calculated hp value for every 100 RPM over the full band for which we have data.

 

It then determines how wide the 30% collection band is by taking 30% of the redline. If the car has a 7000 RPM redline, its 30% band is 2100 RPM wide, which is 22 of the 100 RPM increments.

 

Beginning at the bottom of the known rev range, it adds up the first 22 consecutive values and saves that total as the current-highest-horsepower value. Then, it starts over at the next-to-lowest increment and adds up 22 consecutive values, then compares that to the previous high hp to see if the new number is larger. If so, it replaces the current-highest-horsepower value with the new value. If not, it leaves it alone.

 

This process of iteratively totaling all the possible 2100 RPM bands (in this example) continues until it makes it through the band that ends at the redline. Whichever of all those possible 2100 RPM bands generated the highest raw number is the one that is used, regardless of where that band fell in the overall rev range.

 

The resulting high value is then divided by the number of increments in each band (22, in this example) and the result is the highest average horsepower.

 

That's how it works.

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7VO-VOM

Scott,

 

Thank you for the clarification. I figured that is how it would work. Now, how it doesn't work...

 

Using your 2100rpm range example, let's say somebody has a close ratio gearbox where they only use 1050rpm. They now have 1050 rpm that is completely useless to them. (Yes, that's not 100% realistic, but 1050/1250/1450 doesn't matter). They can have a tuner drastically decrease the HP outside their 1050rpm range. If they don't have an easily tuned car, they could use different cams, an exhaust baffle, and several other methods to kill power. They can drop the HP in unusable rpm ranges by 100 and lower their average by 50hp, but not detune the usable rpm range at all. They now have a huge advantage that wouldn't exist in the current system. Is 50hp too extreme? How about 5 or 10hp? People spend $3000 on headers for 10hp that everybody else can get, you don't think they'll spend $2000 on a tune for 10hp that an older 911/944/E30/E36 can't get easily?

 

Somebody said the dyno sheets would be monitored for retuning like this. How does that work? How are you going to write a rule to prevent it? An F1 style engine freeze? What about people like me who have no existing dyno sheets? What about people like McDonald's Racing doing an E46 V8 engine swap now? What about people who blow up their engine, or build a stroker, or change cams, or upgrade to ITBs, or change to aftermarket ECUs? Preventing people from taking advantage of the rule is completely unenforceable.

 

The only way to prevent that is by narrowing the range. Is it worth all the aggravation and logistical nightmares to measure 1500, 1000, 500 rpms instead of a single point which will have a sweeping curve ahead of and behind it (unless it's right before redline cutoff, but you'd ignore that anyway)?

 

Then you have to consider bending past what most of us would consider the 'spirit of the rules'. Dyno runs are generally done in a gear with close to 1:1 ratios. What is to stop somebody from making different maps for different gears. 1:1 in an E9x DCT trans is 7th gear. Has anybody running a DCT even hit 7th gear on track? In 7th gear, a person could have a nice clean normally looking curve with a single peak, while every other gear could have a nice flat 'detune' curve like in your example. Now before anybody says this is cheating, I'll point out that many modern stock ECUs do this. I don't know if BMW or Porsche do it (but I would assume the SUVs and heavy sedans do). Mercedes certainly does in their insane HP AMGs, and every diesel pickup manufacturer does it.

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Scott,

 

Let us grant that you have a point, that there is a better way to measure the performance of a car than looking at one data point for its highest HP.

 

Lets further grant, by your own examples and postulates, that cars run real world transmissions and differentials.

 

Why is a % figure of the total rpm width more fair than just saying a 2000 rpm range of peak power?

 

The answer is that it is not more fair, it is less fair.

 

If you say that it is adequate to look at only 2100 rpm to judge the power of that 7000 redline car, then it is equally adequate to only look at 2100 rpm to judge the power of a 9000 redline car.

 

By letting the 9000 redline car be judged over 3000 rpm, you give the edge to that car when you yourself concede that you only need 2000 rpm to evaluate a car's performance envelope properly.

 

Swap 30% for 2100 rpm, and you have my blessing, as well as, I suspect the rest of the crowd.

 

Why not?

 

This takes away a LOT of "gaming" risk, who's to say what redline is? So easy to adjust that on the fly too... Turn in a dyno chart, and look at all of it, and pick the highest average HP over any given 2000 rpm range....

 

If you want to average power over a given range vs a single data point, fine, but make it a 2000 rpm range, and everyone is on the same playing field more or less.

 

 

So, two pointed questions I'd like answered by the Decision Makers:

 

1) Why is a % figure of the total rpm width more fair than just saying a 2000 rpm range of peak power?

 

2) Why is it too late to change from an unfair 30% span of rpm for your calculation vs a much more fair 2000 rpm range?

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7VO-VOM

xobgyn,

 

A percentage is actually more fair than a set rpm number. Transmissions are ratios. Compare your 9000rpm motor to a 3000 rpm turbo diesel. The 9000 rpm car will probably use around 3x the rpm range in each gear. If they run the same tranny, they will run exactly 3x different rpm ranges. The percentage proposed covers that. 30% would be 2700 vs 900. Realistically, that should be 900-1500 vs 300-500 to avoid most of the problems I mentioned above.

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911.racer

 

 

So, two pointed questions I'd like answered by the Decision Makers:

 

1) Why is a % figure of the total rpm width more fair than just saying a 2000 rpm range of peak power?

 

2) Why is it too late to change from an unfair 30% span of rpm for your calculation vs a much more fair 2000 rpm range?

 

 

So, how about a third option. One that would be 30% or 2000 min. That way you would have 2000 if the car had a redline under 6700 rpm, but would be measured on the 30% scale if it had over 6700 rpm ?

 

Thanks

 

Ed

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