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2021 Rules Time--How about no changes?


Greg G.

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Hi Folks, it's time to get the 2021 rules published soon.  With the crazy 2020 season (and/or lack thereof), I don't know that we really have any data showing that any of the ST rules should be changed.  Some of the events have once again proven the ST formulas in the various classes to provide tight competition at the top of the fields.  So, maybe we should just update the wording for '21, add the few provisional classifications approved in '20, and save money and time on new modifications needed to keep up with rules revisions!

With that said, we will entertain other ideas posted here.

EDIT:
The Rules were approved in October, and no substantial changes were made.

Edited by Greg G.
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codename Bil Doe

Change ST formula to (horsepower + torque)/2

It simplifies calculations and covers the biggest loophole that people in the know take advantage of. A power-to-weight formula does not account for torque made below 5252 rpm. Top speed is a function of horsepower and CdA. Acceleration is dependent on available torque. It's why the joke (but true) response to "what car should I build for STx?" is always C5Z (or turbo or SC).

Simple example:

•3 people with 3 identical cars

•Each car makes a flat 200hp from 2000-8000 rpm.

•1st person uses 2000-4000 rpm powerband ; 2nd uses 4000-6000 rpm ; 3rd uses 6000-8000 rpm

 

Here are the equivalent torque calcs for every 1000 rpm:

RPM           HP           TQ

2000       200      525

3000       200      350

4000       200      263

5000       200      210

6000       200      175

7000       200      150

8000       200      131

 

•1st person running engine 2000-4000 rpm : 200 hp avg , 379 tq avg

•2nd person running engine 4000-6000 rpm : 200 hp avg , 263 tq avg

•3rd person running engine 6000-8000 rpm : 200 hp avg , 152 tq avg

 

Identical cars and all legal at 200hp, yet it's obvious who will and won't win off corners. You can average 600 data points. "Power-to-weight" leaves a big loophole open by ignoring torque-to-weight.

On the other hand, if it isn't fixed this one of the loopholes people need to take advantage of when building an engine for an ST class. Turbo/SC/V8 to 600lbft @ 2000rpm, 180whp at 6000 rpm redline.

 

Can divide by CdA for aero balance, but that's the advanced class.

 

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And, if we're being honest, points for engine placement looked at again.  I know we took a lot of slack in the past for P-Car's getting points for rear engine placement but that's really only because certain drivers don't make up the difference then and complained.  C8's and Caymans/clubsports starting to show up and they can't technically be assessed the same as a C7 nor can a 911.  Each of the other orgs accommodate for this typically.   As it sits only AWD's are getting penalized for orientation.  That's only half the equation as mentioned above.  Time to update.

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Acceleration is based on power available.  A moving object has a certain amount of kinetic energy depending on speed and mass (KE = 1/2 M * V^2).  Units for energy are J(oule) aka Watt * second.  1 horsepower = 757 Watts.  So, exert power for a set amount of time and you add kinetic energy - aka you accelerate.  If you're going to discuss torque then we need to compare transmission and differential gear ratios along with tire size so that we can understand torque's effect as a force to move an object, but if you do all that, you'll reach the same conclusion as you would if you just compared power.

There is a reason in your example #1 has an advantage over #3 but it isn't torque.

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Tansar_Motorsports

I agree strongly with ssmith.

From a mathematical standpoint, TRQ does not matter.  Power determines acceleration.
Too many people have been brainwashed by the idea that "TRQ wins races".
Mathematically, TRQ is an instantaneous value, it has no time component.  Meanwhile, 1 HP  = 750 Watts.  A Watt is 1 Joule per second.  Joule is the standard unit of energy.  Therefore, if we multiply our power by time, we can calculate how much energy we have added to our vehicle.  In this case, kinetic energy.  Velocity is proportional to kinetic energy (KE = 1/2 M * V^2).  Therefore, our change in velocity (acceleration) is directly proportional to Power * time.

ex. accelerating at 200 HP for 10 seconds adds 200*10*750 = 1.5 million Joules of energy to our car.  Starting from an initial speed of zero, in a car that weights 1000 KG,  the velocity would increase to 54 m/s = 194 km/h = 120 mph.  Note, this example ignores wind resistance and rolling resistance.
Therefore, we achieve an average acceleration of 54m/s / 10 seconds = 5.4m/s^2
Look at that, we calculated acceleration without needing to consider TRQ, RPM, or gear ratio!
Power/weight ratio is the correct way to balance a multi-car class, because it eliminates differences in available gear ratios and max RPM.

In Bil Doe's scenario above, he did not consider gear ratio.
If all 3 cars are exiting the corner at the same speed, at 2k, 4k, and 6k rpm respectively, then they must have very different gear ratios, changing the effective wheel TRQ of each vehicle.

Edited by Tansar_Motorsports
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12 hours ago, Tansar_Motorsports said:

I agree strongly with ssmith.

From a mathematical standpoint, TRQ does not matter.  Power determines acceleration.
Too many people have been brainwashed by the idea that "TRQ wins races".
Mathematically, TRQ is an instantaneous value, it has no time component.  Meanwhile, 1 HP  = 750 Watts.  A Watt is 1 Joule per second.  Joule is the standard unit of energy.  Therefore, if we multiply our power by time, we can calculate how much energy we have added to our vehicle.  In this case, kinetic energy.  Velocity is proportional to kinetic energy (KE = 1/2 M * V^2).  Therefore, our change in velocity (acceleration) is directly proportional to Power * time.

ex. accelerating at 200 HP for 10 seconds adds 200*10*750 = 1.5 million Joules of energy to our car.  Starting from an initial speed of zero, in a car that weights 1000 KG,  the velocity would increase to 54 m/s = 194 km/h = 120 mph.  Note, this example ignores wind resistance and rolling resistance.
Therefore, we achieve an average acceleration of 54m/s / 10 seconds = 5.4m/s^2
Look at that, we calculated acceleration without needing to consider TRQ, RPM, or gear ratio!
Power/weight ratio is the correct way to balance a multi-car class, because it eliminates differences in available gear ratios and max RPM.

In Bil Doe's scenario above, he did not consider gear ratio.
If all 3 cars are exiting the corner at the same speed, at 2k, 4k, and 6k rpm respectively, then they must have very different gear ratios, changing the effective wheel TRQ of each vehicle.

Thanks!  I started to write this one out last week, and ran out of time--hoping that someone would make the statement and bring the physics formulas out.

I think that the big thing that gets missed is gear ratio, and also that often those "high torque" vehicles just have a much wider range of usable "flat" horsepower, requiring potentially less gearshifts (which is something, but we do attempt to compensate for this with our "Avg HP" formula.)

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I vote for no changes. As Greg stated, 2020 was a disjointed and shortened season. With various activity restrictions persisting in some places and many folks dealing with business disruptions, now isn't a great time to make rule alterations that require jumping through hoops to reconfigure cars for classification purposes. IMO, any rules changes should be  limited in scope and easily implemented.

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  • 2 weeks later...
hansbliss99

For years the people that raced NA motorcycle engines know that power to weight ratio is unfavorable in long tracks. Top speed of a Thunder Roadster is 140mph so racing in tracks with long straights the car can not keep up with Porsche's, Corvettes or BMWs. It is completely illogical to put a 140mph car vs a Porsche Cup Car in ST2. Even in ST3 the car is not competitive on those tracks with that max speed.
Something similar happen with radical SR3 with a 150mph max speed there is no business to take it in Super Unlimited at Daytona next weekend. 
 

Can we make it a fair game? We have seen the issue for a long time and.....

Thank you!

 

Hans Bliss

Bliss Racing 

NASA SE

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First of all I agree that no changes for 2021 is the smart move.

I also understand how impossible it is to get a perfectly level playing field. However, I do agree that it would be great to find some way to consider raw horsepower numbers in classifications. As stated above high horsepower cars just run away from the similar lower powered cars in their class on big tracks. As we all know drag and horsepower matters way more than weight once you get going fast. Perhaps some kind of penalty on top of the current formula as horsepower exceeds a certain low thresh hold in each class?

Otherwise I'm gonna build the 5500lb 600hp TT4 Mercedes I've been dreaming about for years and just destroy the competition at big tracks! :)

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My home track (NOLA) has a long main straight and I've seen cases where lightweight/low-HP/low-top-speed cars get held up in the turns and blown past on the main straight. It's even happened to me by out-of-class racers that have done the same. But if you put in a correction factor to minimize this effect on big tracks, wouldn't that skew things in the other direction on tight tracks? Also, how much of the problem being described here is really because of LW/low-HP vs draggy and/or high downforce designs? A few of the really lightweight cars that suffer this effect are aero bricks at high speeds. Seems as if it'd be difficult to have one set of correction factors that could account for aero drag and/or absolute power/absolute weight effects across widely differing automotive designs in a way that kept everything equal on every possible track.

Any given rule set is likely to favor some cars on certain tracks and other cars on different tracks. This is true even at the top level of professional racing.

Right now, there is a modest mod factor penalty for cars below a certain absolute weight and a bonus for cars above a certain absolute limit. NASA must have had a reason for imposing that system, which goes directly against the proposals being submitted here.

If NASA does impose some new change because of this, I hope (a) They don't do it until 2022 at the very earliest, (b) It doesn't require a large fraction of participants to hack up our cars, add tons of ballast or spend a fortune adjusting to the rules.

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Since it was a shortened season can we allow the Continental EC wet to remain in 2021 as a DOT tire? I know it was suppose to end in 2020 but I’m probably not the only one that still happens to have a sticker set sitting around.

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With turbo cars having low-end TQ changes the competitiveness of the vehicle hugely. While you don't have top-end HP or great top speed, you take off from corners like a rocket and maintain it thru and thru. A recent example of this was actually in Runoffs with Ecoboost Mustangs. 

-Ali

Great Lakes. 

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In our region, we have had a number of competitors (who have all run Hoosiers or Hankooks for years) try to use a 100TW Tire and use the .6 mod factor.  These are all winning drivers both regionally and nationally.  All proved that the .6 mod factor is not enough to overcome the lack of grip and its impact on lap times as compared to the Hoosier or Hankook.  We tested it one weekend with a Hankook Z214 against the Toyo RR (same car, same very consistent driver).  HP was changed to account for the .6 mod factor.  Lap times were still off 1.5-2 seconds with the higher HP and the data showed that while the car was able to reach a higher top speed, the loss of time in each corner due to less grip, was nowhere near made up for with the extra HP/higher top speeds.  The other drivers who tried, all switched back to Hoosier or Hankook as well.  We should consider increasing the .6 to 1.0 for a 100TW tire like a Nitto, Toyo, or otherwise to provide more options for the grassroots racers in ST4 and give them a realistic chance at the podium.  Couple that with the fact that we now have drivers in ST4 running 3-4 sets of new tires per weekend, the chances for the 'little guy' keep diminishing.  We might consider limiting the number of sets of NEW tires used each weekend to 2 - which is still more than the average Joe can afford and would be more inline with the intent of ST4-ST6.  I run Hoosier by the way, but I would like to see more options for others as I see them becoming discouraged by the lack of realistic alternatives.  

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That's always been a problem in the spending game of racing.  People who can run fresh A's in each session, will do so for that edge it provides.  That's true with EVERY single racing series out there.  You'd instead have to impose that ST4-6 ran Toyo RR's as a spec tire compound in order to pull that off, but then you'd piss off the other brands and its already sketchy with BFG and others leaving.  We're LUCKY hoosier keeps coming back as it is simply due to the amount of tires we buy.

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Balroks, that may be somewhat the case, but limiting the number of sets of new tires used each weekend is not a new concept nor is it unusual - look at Trans Am and many other series with far larger budgets than we have.  The bigger picture is allowing for the other tires (like an RR or other non Hoosier or BFG or Hankook) to actually have a chance.  The current mod factor isn't enough for that to be case, and it would be nice to give some of the other tires and competitors without the budgets a chance.  Again, nothing against Hoosier or anyone who uses them (including myself) but we need some diversity on the podiums.

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  • 2 weeks later...

Sorry for the late reply.  

I'm OK with no rules changes at this time, however I will agree with the people above that a +1.0 modifier is at least a trend toward the right direction with 100TW tires and higher.  While i have experience with the tires from various enduros, and know the pros/cons of them, I don't use data, so I can't provide you any "look at this" stuff, other than lap times.  Granted it's easy to compare averages amongst SCCA vs. NASA SM drivers that run between both clubs, and with relatively similar weather and track conditions.  

HOWEVER, I would like to see clarification on some rules, that I have seen numerous new.....and old members become consistently confused by, and I even find them to be confusing.  I say this as a member, and to save yourself the frustration of numerous emails.  Below are examples of questions I have seen asked by MULTIPLE people:

 

Quote

6.1.3 Chassis and Body Modification Limitations

1) Other than the listed exceptions, every vehicle must retain its unmodified: 1) OEM frame rails/rear frame cross beam, and/or Unibody, and Sub- frames/suspension cross-members (in their OEM locations). 2) Strut/shock towers 3) Inner/inboard side of the fender wells (any non-horizontal aspect) 4) Rocker Panels 5) Transmission tunnel 6) Floor pan 7) Windshield frame location 2) The following are the permitted exceptions to #1 above:

1a) Frame rails, sub-frames/suspension cross-members, and unibodies may have maximum diameter 0.75” (3/4 inch) holes drilled into them for purposes other than lightening, such as for the attachment of ancillary parts. Cutting and channeling is not permitted.

1b) Frame rails may have maximum diameter 1.25” (1-1/4 inch) holes drilled solely for the purpose of the placement of jacking lugs/plates

 

So the issue here, is typically with Miatas that have frame rail supports such as Flyin Miata frame rail supports.  This is something that can then be used as a jack point on a miata, however it does offer some chassis rigidity, albeit very little without the addition of a butterfly brace.  I really don't care either way, but the confusion with the rule requires clarification for the sake of some miatas within the class. 

 

Quote

1c) Bump steer kits are permitted. “Drop spindles” (spindles that have had the axle shaft relocated upward) are considered a relocation of suspension mounting points, and are not permitted.

Define "bump steer kits".  Are inverted tie rods allowed with longer tie rod mounts allowed?  Are SCCA Spec Miata steering rack shims allowed?

Quote

1d) Modifications of non-subframe/non-suspension cross-members (other than the rear frame cross beam), transmission mounts, differential mounts, and radiator core supports are permitted.

Are FWD traction bars that replace the stock cross member, that holds radius rods that attach to the lower control arms legal?  Looking at this rule, it appears so, however while it is not "technically" a part of the suspension, the radius rods hold the lower control arm of the suspension forward during acceleration.  Denoting explicitly that "traction bars are legal/illegal" aides in this area.  

Quote

6.1.4 “BTM Aero” Modification Factor Vehicles that maintain the unmodified Base Trim Model (BTM) body lines, do not have non-BTM aerodynamic aides or modifications, and do not have a rear wing or rear spoiler or rear diffuser, may assess the Modification Factor for “BTM Aero” in calculating the “Adjusted Wt/HP Ratio”. Under this specific rule, an aerodynamic aide is considered non-BTM if it did not come configured on the base trim model (BTM) of the vehicle from the manufacturing factory. Except for those vehicle-specific higher level trim models (non-BTM) listed in Appendix B, there is no updating or backdating across trim models or the addition of dealer installed options permitted.

I understand this rule, however numerous others do not, and I think the wording of it creates confusion.  Greg....you should be able to relate easily, as a great example(while not ST6 legal), would be a Neon SRT-4 with an "OEM" rear wing and front fascia, as there is confusion as to whether the SRT4 is BTM or if the base neon is BTM.  People are easily confused on similar cars as to whether or not this is available for them or not.  Similarly with SVT vehicles, etc.  

 

Quote

6.1.5 ST6 Aerodynamic Modification Restrictions and Limitations Active aerodynamic devices and/or modifications (including, but not limited to computerized, cockpit adjustable, self-adjusting, and OEM) are not permitted. If not using the BTM Aero Modification Factor, aerodynamic parts/devices/aides shall be limited in ST6 to the following:

3) Modified BTM, non-Base Trim Model (non-BTM), or replaced front fascia (unless specifically approved in Appendix B: i) May have nothing attached to it other than specifically allowed items (above). ii) May not have canards/winglets molded into it. iii) Any item that is molded into the fascia during the original manufacturing process that functions as an airfoil, deflector, dive plane, or vortex generator and extends 2" or more past the outline of the immediate surrounding fascia is prohibited. To inspect: a plumb line run across the entire surface of the fascia and bumper shall not have any such item that extends 2” past the line when viewed from above.

This has been probably the single biggest source of confusion for fellow ST/TT6 competitors.  We have had multiple people show up with full air dams in ST/TT6, when air dams are not legal.  Somewhere this needs to be clarified, that air dams are explicitly not legal in ST/TT6, to make that concrete.  As another point, what is an example of this rule?  Would a 1.8 spec miata with fog lights that are legally covered with tape in SM, then no longer qualify for BTM Aero +0.4 in ST6?  I think it's vital to provide common examples to clarify. 

 

Quote

6.1.8 Transmission Limitations

1) Non-OEM Transmission swaps are only permitted when used in conjunction with an engine swap. Note--The transmission must come from the same donor vehicle model as the engine, and that donor vehicle must be a model eligible to compete in ST5 and ST6, respectively (sections 4 and 6.1.1). Otherwise, the transmission must be OEM.

A bit ambiguous...or at least confusing wording.  So if you swap an NB Miata 6 speed transmission, it is not legal in an NA 1.6 miata, since you didn't swap the NB 1.8 engine with it, or would it be legal because it is an "OEM" transmission via updating/backdating from prior rules wording?  What if you swap a Honda K engine into a Miata?....what transmissions are you allowed to use? 


LASTLY, For your own sake Greg....and you would know better than all of us, adding an appendix of examples, or at least a "FAQ"ish section, as I'm guessing you get asked similar questions frequently.  Clarity, especially with common examples, would make a world of difference.  It wouldn't require much wording change of rules other than "See appendix D for examples".  The wording, regardless of how concise, can sometimes still be confusing in some cases, so if you can think of more common example as to what is legal and illegal then portray them in an appendix, it would be highly beneficial for current, and most especially for potentially new members.  

 

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6.1.8 Is pretty limiting when it comes to swaps and could result in extra expense and or poor reliability. What about swapping a FWD drive only engine into a rwd vehicle? Could at least make it the same manufacturer as the donor engine and ST5/6 legal, though in the spirit of ST and to keep cross make bolt on options open, just ST5/6 legal would suffice. This would also allow some more affordable options for transmissions.

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  • 3 weeks later...

I want to +1 some form of tire limit in ST4-6 (and TT).

It's not uncommon in our neck of the woods to see competitors use 8 tires per weekend. That's a super hard advantage to overcome without joining the arms race.

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The A Arm Penalty. Currently at .7

How about 3.5 per axle? We front strut BRZ get penalized (running tons of camber, without the benefits enjoyed by S2K/RX8). 

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Tansar_Motorsports
21 hours ago, lutfy said:

The A Arm Penalty. Currently at .7

How about 3.5 per axle? We front strut BRZ get penalized (running tons of camber, without the benefits enjoyed by S2K/RX8). 

I agree completely.

And while we are at it, more explanation and definition must be created to clarify the differences between double A-arm and multilink. 
At what point is a multilink rear sus equivalent to a double A-arm rear sus?
Can we define rules for evaluating / measuring a multilink geometry?
Or, should we just create an appendix, listing all of the multilink geometries that should be treated as double wishbone?

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On 10/14/2020 at 6:36 PM, NorcalTT said:

Balroks, that may be somewhat the case, but limiting the number of sets of new tires used each weekend is not a new concept nor is it unusual - look at Trans Am and many other series with far larger budgets than we have.  The bigger picture is allowing for the other tires (like an RR or other non Hoosier or BFG or Hankook) to actually have a chance.  The current mod factor isn't enough for that to be case, and it would be nice to give some of the other tires and competitors without the budgets a chance.  Again, nothing against Hoosier or anyone who uses them (including myself) but we need some diversity on the podiums.

My vote is for max 1 set per weekend, a set of r7 drives great the duration of the whole weekend 

that would also help the 100tw tires catch up if those are more consistent on the second day

should be a no brainer is club racing 

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17 minutes ago, esr said:

My vote is for max 1 set per weekend, a set of r7 drives great the duration of the whole weekend 

that would also help the 100tw tires catch up if those are more consistent on the second day

should be a no brainer is club racing 

Would have to qualify on the race tires 

and have only  2 Sessions on Sunday both races

 

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Tansar_Motorsports
19 hours ago, esr said:

My vote is for max 1 set per weekend, a set of r7 drives great the duration of the whole weekend 

that would also help the 100tw tires catch up if those are more consistent on the second day

should be a no brainer is club racing 

I would say 1 set to be used for qualifying and both races.

And an allowance to use different tires for the practice / warmup sessions (most people will just use an old set of tires for this).  Otherwise, people will be skipping the warmup/practice in order to preserve their 1 set of stickers for qualy / race.  Not the intention.

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15 hours ago, Tansar_Motorsports said:

I would say 1 set to be used for qualifying and both races.

And an allowance to use different tires for the practice / warmup sessions (most people will just use an old set of tires for this).  Otherwise, people will be skipping the warmup/practice in order to preserve their 1 set of stickers for qualy / race.  Not the intention.

2 races on Sunday instead

Edited by esrsf1
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