2016 Proposed ST Rules Revisions

[loftygoals]

50rpm vs 500rpm will have a large effect on flat torque engines because the closer the resolution the smaller the extra hp a peaky engine will get.

 

Just to be clear, no one is debating the distance between sampled points--that's still 500 RPM. The 50 rpm number would simply be the intervals on the report. So there isn't a 500 vs. 50 debate. Simply a discussion on the reporting intervals.

[PoBoyR6]

There should also be a contingency if the same peak HP occurs at 2 different points on the dyno that the equation is calculated for both peak HP points and the one with the higher average will be used.

 

Solid catch of a gotcha and good a resolution to boot!

 

Agreed. But this now leads to the question of what decimal accuracy are we taking the HP table to for the purposes of the calculation? If its x.xx like WinPEP spits out then the odds of same peak HP numbers are slim to none. If the HP numbers are to be rounded to the nearest whole number, then this situation is much more likely.

 

Either way to what HP decimal point we are to be plugging into the avg calc should be defined.

[davidfarmer]

one of the previous posts seemed to have missed the 50rpm breakdown, my mistake if I misunderstood their misunderstanding

 

It was round to the nearest whole number in the past....I'm all for keeping it the same. I don't think decimal hp doesn't win races, BUT every tenth of a HP is a whole pound of weight now! Half a HP is almost a gallon of fuel!

 

 

I'm heading to pull some files from my Winpep this morning. I've not exported at 50rpm yet to see if it makes any meaningful differences. Honestly, if you can hide a HP "bump" in a 50rpm increment, it isn't doing you enough good to matter!

[loftygoals]

...BUT every tenth of a HP is a whole pound of weight now!

 

Honestly, if you can hide a HP "bump" in a 50rpm increment, it isn't doing you enough good to matter!

 

David,

 

My concern wouldn't be an intentional bump as much as the natural change between data points. If we used 100 RPM increments, you could be shifting +-50 RPMs from the spot you actually want to measure. This could change the overall average by +-5hp. As you pointed out, 5 horse power is 50#--which is a lot of weight.

 

In my mind, the discussion about the increments is about making the system fair, not catching people gaming the system.

[hispanicpanic]

So far so good on the power rules. I'd just like to add that the range for power should be equally considered important as the resolution on which power is reported. 3 points around your highest peak hp is only a 1500 rpm spread. People with a super flat hp curve are still at an advantage compared to a B series honda, no?

 

I have to be honest though. I was hoping to see some points given back for people running street tires. That would help with participation immensely.

[Brian L.]

 

I have to be honest though. I was hoping to see some points given back for people running street tires. That would help with participation immensely.

 

Since this is the ST debate and not TT (yes I know they are the same class), lets just imagine that no one racing in a class as fast as ST is running street tires . People driving their cars to the track in TT might like this, but for the class as a whole it doesn't make sense.

 

This goes back to the question someone raised about giving Toyo's a break because they are not as fast ass Hoosier's/Yokohama's. At some point you have to understand you can't run a certain tire to be competitive in a class. I would never expect the rules to make sure I am competitive on my set of all season tires, it just isn't realistic.

 

Now maybe in the future for an ST4,5,6 where the budgets are much lower, cars are much slower, and specific budget limiting rules are in place that might make sense there, but it will never make sense in ST1,2,3.

[ILIKETODRIVE]

I have to be honest though. I was hoping to see some points given back for people running street tires. That would help with participation immensely.

In ST? Not really. Nobody would run street tires in ST even if it was a +1.0 adjustment.

 

In TTE/TTF/PTE/PTF? Maybe.

 

For instance:

SM6 is a +8 tire. A 205 on my car would be +1 total.

RS3 is a +2 tire. A 225 on my car would be +1 total.

I would run the SM6 as-is.

I would shave the RS3 to 2/32nds.

 

Having driven both...SM6 hands down.

 

Knock off that +2 so that a shaved 205 street tire (like the Federal RSR) would be -7 instead of -5? Now we're talking. That's a * I could use.

 

Would it be faster? Probably not. Would it be economical? Not if I'm winning Hoosiers.

Would it make it more fun to try to beat the local competition on a 205 street tire and have a TTE* base vs a TTE base? Sure.

[Greg G.]

Guys,

 

1) I've done data sample exports at 50rpm, and there is no reason to not use the actual Max HP on the graph, instead of the Max HP on the data export. This will also make the

issue of two possible Peak HP data points moot.

2) We can use 50 rpm increments for the data export, and then use the Max HP on the table as the starting point to obtain the other data points in 500 rpm increments.

3) Round all HP numbers to a whole number before any calculations.

4) The idea regarding the two identical rounded peak HP numbers does bring up the very unlikely case where there is enough of an rpm band at +/- 2500 rpm that someone could build

a "false" hp curve at one of those peaks. So, we may need to expand the range (as David stated above 5000 rpm) to +/- 4000 rpm. In reality, when you look at a printed graph, and

print out the data export, one is usually only having to pull look at 5-6 of the extra data points (not all 10) to find the three needed.

5) I'm going to see if Dynojet will work out a data export for us. If anyone has an contacts directly with Dynojet, contact me.

6) For compliance inspections, we will use the run with the highest Ave HP (or Avg HP if I must ), and not necessarily the run with the highest Peak HP.

7) Also, there will be a rule about having the engine instrumented to obtain rpm, not calibrated against the vehicle's tachometer. If for whatever reason, this is a complete impossibility,

then it must be noted on the Dyno sheet and Dyno Certification Form.

[loftygoals]

7) Also, there will be a rule about having the engine instrumented to obtain rpm, not calibrated against the vehicle's tachometer.

 

I assume by "instrumented" you mean using the inductive pickup on a coil wire or coil pack lead, right?

 

I hadn't thought about the fact that someone could use a modified tach signal by manipulating the tach output configuration on the ECU to skew the results. <- This is a really smart way to cheat! I'm glad you've got it covered, though!

 

-bj

[Greg G.]

7) Also, there will be a rule about having the engine instrumented to obtain rpm, not calibrated against the vehicle's tachometer.

 

I assume by "instrumented" you mean using the inductive pickup on a coil wire or coil pack lead, right?

 

I hadn't thought about the fact that someone could use a modified tach signal by manipulating the tach output configuration on the ECU to skew the results. <- This is a really smart way to cheat! I'm glad you've got it covered, though!

 

-bj

Bingo

[Balroks]

Also consider Mustang, Pak, Dynamics etc and what configurations they use/could offer, 3 of the tuners we normally use in the area are all mustang's for that whole eddy current/price point. And I believe they don't use coil pickup's but more of a "ok hold it at 4k in 4th" and it calibrates itself from there. I would hope as cumbersome and costly as it is to get the cars on the dyno people wouldn't waste time with manipulating RPM's, but some people have nothing more then time and money .

[J_Roberts]

So I looked at my numbers a little closer on the 500 RPM increment, and here is what I see. I compared two different power curves, one normal NA, and one flat FI/TBW with a peak that takes advantage of the 500 RPM increment (TBW = Throttle By Wire)

 

Both have the same Average HP per the proposed rule (312 WHP)

FYI for the math/engineering geeks (like me), I used the trapezoid method to calculate the areas under the power curves. The FI/TBW power curve has more area under the curve in all cases compared to the NA engine, in some cases considerably:

Between 3500-6500 RPM, the FI/TBW has 12% more area

Between 4000-6500 RPM, the FI/TBW has 14% more area

Between 4500-6500 RPM, the FI/TBW has 4% more area

 

So, even with the averaging formula, a FI/TBW car could still gain a significant power advantage, especially if they carefully chose their shift points. In this example, optimum would be 4000-6500 RPM. Incidentally, I spoke with a Mechanical Engineering friend of mine, former racer, that works in a serious engine R&D group, and they indicated that area under the curve is really the only way to compare two engines in this context.

 

Here's the two plots. Granted, the peak on the FI/TBW graph is a bit extreme, and is for illustration. However it can be achieved with readily accessible tuning means (already being used), and is legal by the proposed calculation method (as I understand it).

 

 

 

Here is the data I used for the above:

RPM FI NA

2500 200 200

3000 250 250

3500 290 280

4000 300 300

4500 305 316

4700 335 321

5000 340 323

5300 335 318

5500 302 310

6000 300 290

6500 300 250

Edited November 13, 2015 by Guest

[loftygoals]

Here's the two plots.

 

FYI - Your linked image isn't being displayed.

[J_Roberts]

FYI - Your linked image isn't being displayed.

 

Image hosting problems. Should be working now. Sorry about that.

[mhoward1]

So I looked at my numbers a little closer on the 500 RPM increment, and here is what I see. I compared two different power curves, one normal NA, and one flat FI/TBW with a peak that takes advantage of the 500 RPM increment (TBW = Throttle By Wire)

 

Both have the same Average HP per the proposed rule (312 WHP)

FYI for the math/engineering geeks (like me), I used the trapezoid method to calculate the areas under the power curves. The FI/TBW power curve has more area under the curve in all cases compared to the NA engine, in some cases considerably:

Between 3500-6500 RPM, the FI/TBW has 12% more area

Between 4000-6500 RPM, the FI/TBW has 14% more area

Between 4500-6500 RPM, the FI/TBW has 4% more area

 

So, even with the averaging formula, a FI/TBW car could still gain a significant power advantage, especially if they carefully chose their shift points. In this example, optimum would be 4000-6500 RPM. Incidentally, I spoke with a Mechanical Engineering friend of mine, former racer, that works in a serious engine R&D group, and they indicated that area under the curve is really the only way to compare two engines in this context.

 

Here's the two plots. Granted, the peak on the FI/TBW graph is a bit extreme, and is for illustration. However it can be achieved with readily accessible tuning means (already being used), and is legal by the proposed calculation method (as I understand it).

 

 

 

Here is the data I used for the above:

RPM FI NA

2500 200 200

3000 250 250

3500 290 280

4000 300 300

4500 305 316

4700 335 321

5000 340 323

5300 335 318

5500 302 310

6000 300 290

6500 300 250

 

Going through the basic formula though, it seems the FI advantage is recognized:

 

FI NA

340 323

335 321

335 318

305 316

 

Average HP :

328.75 319.5

[loftygoals]

Going through the basic formula though, it seems the FI advantage is recognized:

 

FI NA

340 323

335 321

335 318

305 316

 

Average HP :

328.75 319.5

 

You did the calculations incorrectly. The correct data points are:

 

RPM FI NA

2500 200 200

3000 250 250

3500 290 280

4000 300 300 -1000

4500 305 316 -500

4700 335 321

5000 340 323 Peak

5300 335 318

5500 302 310 +500

6000 300 290

6500 300 250

 

FI: (300 + 305 + 340 + 302) / 4 = 311.75

NA: (300 + 316 + 323 + 310) /4 = 312.25

[J_Roberts]

 

You did the calculations incorrectly. The correct data points are:

 

RPM FI NA

2500 200 200

3000 250 250

3500 290 280

4000 300 300 -1000

4500 305 316 -500

4700 335 321

5000 340 323 Peak

5300 335 318

5500 302 310 +500

6000 300 290

6500 300 250

 

FI: (300 + 305 + 340 + 302) / 4 = 311.75

NA: (300 + 316 + 323 + 310) /4 = 312.25

 

Yes my calcs agree with loftygoals. I rounded to the nearest HP and calculated 312 for both.

 

If anyone is interested, I have more example data, with a third high-RPM NA engine added. Same process, that is all have the same calculated power, but have different areas under the curve. For this example, I used 250 RPM increments, and the top 6 HP readings (5 plus peak). The FI/TBW engine still has an advantage, but the tighter interval decreases the difference.

 

The point of all this though, is that you have to be careful about using a small enough interval and enough data points to calculate the average. Otherwise, the FI/TBW cars still have an exploitable advantage, despite the intent to the contrary.

[mhoward1]

Ah, I missed the interval change between 4500 and 5000 RPM.

[Sterling Doc]

Thanks for the calculated dyno curves - illuminating, for sure.

 

It would be interesting to run the calculations for DBW vs. a "peaky" motor.

That is who this rule was designed to help.

If the rule (as is) just changes the desired power curve from flat to a collection of trapezoids, but still has the same benefit to flat/DBW cars, it's a net loss - more complexity without benefit.

These dyno curves would also favor custom, close ratio gearboxes, it would seem.

[hansbliss99]

I appreciate that NASA is working on a formula to make things better but I believe the principal issue right now is not the formula.

 

We need something live that determine the power of the car in the race, no few hours, days or months before or after the race. Then we can use that information to calculate minimum weight.

 

That will stablish a fair level for everyone and avoid so much gossip, accusations and arguments that hurt our sport more that anything else.

 

Hans Bliss

Thunder Roadster ST3

[Balroks]

I appreciate that NASA is working on a formula to make things better but I believe the principal issue right now is not the formula.

 

We need something live that determine the power of the car in the race, no few hours, days or months before or after the race. Then we can use that information to calculate minimum weight.

 

That will stablish a fair level for everyone and avoid so much gossip, accusations and arguments that hurt our sport more that anything else.

 

Hans Bliss

Thunder Roadster ST3

 

Been tested but far too unreliable to properly justify a DQ. Either measured road speed or GPS could be used to determine horsepower. All that is needed is the steady state speed, drag coefficient, frontal area, air density, oh and and tire rolling resistance. And if you permit everyone to run they're own data, and you forget to turn it on or a plug comes loose what then.

[Bnjmn]

Could go in the direction that GTS looks to be heading, which is black box compliance loggers. Cars would need to be wired to provide outputs to the logger. I think GTS was only going to measure TPS, which is not quite enough. Should expand that that spark and fuel, and then compare track readings with dyno readings. Won't be an exact match due to dyno vs real world loading, but would a very good solution.

[loftygoals]

We need something live that determine the power of the car in the race, no few hours, days or months before or after the race.

 

Could go in the direction that GTS looks to be heading, which is black box compliance loggers.

 

As much as I agree that this would be best case, it just isn't possible. There are too many variables and not enough sources of data to make this viable. You could develop an approximation using data from the car, but the margin of error could easily be +-20 hp or more.

 

Part of the issue is that power to weight classes like ST/TT don't evaluate the whole car, only two things: the mass of the vehicle and the engine power output. Everything else that can impact performance is ignored. Thus a on car monitoring system would have to be capable of accounting for things like aero drag changes (changes like different front facia, changes in angles of attack on wings, ride height, etc), gearing changes (both final drive and transmission ratios), tire slippage/wheel spin, tail wind/ head wind, and the list goes on. It just isn't feasible that a "black box" can do this with any degree of consistency.

 

The other issue with black box solutions is how does a racer verify that the car is compliant before a race?

[Balroks]

Pretty much.

 

Around the water cooler some would say keep aero the same throughout the day but then you allow but adjustable suspension, your blackbox # would say the same HP but you may pickup a few tenths in one corner. Then people said well lets do a spec tire, a spec shock, spec fuel, and spec brake pads, then set ST3 to 300hp, ST2 to 400hp, and ST1 to 500hp, and adjust weight penalties from there.

[davidfarmer]

that example doesn't pan out in reality....in my opinion. You only have a 600rpm power range. Even if your transmision is geared so close that you can stay within 300rpm of peak each way, in many cases you'd be making more torque at the rear wheels to rev higher and go into a lower gear.

 

I think the proposed formula is a good start. It certainly gives me no incentive to do anything except develop a relatively flat curve...maybe a high rpm peak for drivability, but nothing crazy.