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2019 NASA TT Rules Overview + 200TW Texas Region Classes!

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  • 2019 NASA TT Rules Overview + 200TW Texas Region Classes!

    I am writing this for a number of reasons. First, we are sponsoring a new 200TW Championship series within NASA Texas Time Trials. We also sponsor Texas Region SCCA autocross and Club Trials events, which we also compete in. We also run in Optima series events, which are completely based around 200TW tires. All of these series have completely different classing systems, which is a bit frustrating. There are a number of folks that like to jump around and run in more than one series.

    Racing budgets are tire dependent: 340TW vs 200TW vs R-compound tires shown above

    When you are used to one way of doing things, it can be overwhelming to try a new series or group of classes - especially when the main aspect of your road course car (the tire) is fundamentally different. NASA Time Trial does not have a good way to equalize 200TW tires vs Hoosier R-compound tires, but this new series of 200TW sub-classes might be a bridge to bring some of those other folks over.

    Optima's Ultimate Street Car Shootout has time trial (and autocross and speed stop) with 200TW tires

    We are not trying to steal competitors from other series, just give them another place to compete with a new group of racers. We hope this "bridge" works both ways, with NASA TT competitors going to try out Optima events and other series as well.

    We hope that this series of posts can serve as an "Unofficial Guide to NASA Time Trial", as well as a discussion of the HPDE / TT / W2W spectrum. We have done this before but updated it heavily for the 2019 NASA Super Touring / Time Trial rules.


    A little history: NASA started their first full season of Time Trial competition in 2003 (that's the Version 1.1 of TT rules, Feb 2003) and Vorshlag has been involved in NASA since 2006.

    Left: My college TT car was a Fox Mustang. Right: Running our LS1 powered BMW E36 with NASA in 2008

    I did my first Time Trial back in 1991 at Texas World Speedway (above left), back before these events were formalized or even called "Time Attack" or "Time Trial". It was a lot of fun, and I ran a lot of HPDE events in the 1990s that got me hooked on road course speeds - but I was I was an avid autocrosser during this period as well. The emergence of a real Time Trial series gave me the road course speeds plus the competition element I missed from autocross, without the costs or risks of W2W racing.

    What is W2W? Let's back up a bit and explain some terms. When it comes to amateur road course motorsports, there are a lot similarities between Time Trial vs HPDE (track driving events) vs W2W Road Racing (Wheel to Wheel, aka: "club racing"). Some say its a ladder, and the only way forward is to continue "up" to W2W. Others see it as a broad spectrum of events that are based on a road course - a spectrum from which you can choose based on what suits your level of commitment, budget, driving style, and level of risk. There is no shame in "only" doing HPDE, or never aspiring beyond Time Trial - don't let people tell you otherwise.

    HPDE events are fun, low risk, and possible in street cars. But if you get the competition bug...??

    At one end of the spectrum is "HPDE" (High Performance Driving Events), which is a fun way to learn track driving skills with lower risk - passing is only done with "point bys" and only on the straights. In-car instructors and structured classroom sessions teach HPDE drivers vital driving and safety skills. But after doing HPDE for a few years, some folks get bored... They start taking lap times, then comparing times with their friends. They often get bit by the "competitive bug"...

    Wheel to Wheel Club Racing is a blast, but with "passing in anger" things can get expensive, fast

    At the other end of this spectrum is "Wheel to wheel" (W2W) road racing at the "Club" level. This is class racing, with a "start to finish" goal (racing to a checkered flag). These races normally run over a 20-45 minute session, with qualifying sessions beforehand to set the starting grid order. But when you ask Club Racers, much of the actual "racing" happens in the first 1-2 laps (or in Qualifying itself), and the rest of the race duration is spent holding off other cars and managing consumables. Every race lap matters, and one mistake can put you back many spots - or put you into a barrier.

    W2W safety: extensive roll cage, no door glass, no interior, cool suit cooler, fire suppression system, window nets, racing harness

    Due to the much higher potential for car-to-car contact, safety requirements are radically higher than HPDE or TT. These cars become dedicated race cars (not street legal), and most racers figure on at least one or two car-to-car contacts per season. Some W2W racers think that every other form of on track experience is pointless, as they are all about "making that pass". Good for them, I say. W2W costs are of course much higher, and many folks end up racing a significantly slower car than a comparable or lower budget would yield in TT competition.

    NASA Time Trial pits a driver against the clock - there is no need to make "passes in anger" for finish placement

    Time Trial sits between these two ends of the road course spectrum, with perhaps the best of both worlds. It has the low risk of HPDE, but with a competition element. TT is essentially identical to Qualifying in any W2W series, but held over 3 to 5 track sessions instead of 1 Qualifying session. A Time Trial competitor's best lap is compared to the top times of other cars in their class, with results tabulated at the end of each day. These results are ranked by class and time, often with contingencies and trophies, but with risks and car wear that are far lower than in W2W. TT cars are often dual-purpose track/street cars, as they do not require a full roll cage (which is usually the tipping point to making a car no longer safe to drive on the street), fire systems, etc.

    You have to earn your TT comp license before you can compete, to make sure you are safe to share the track with

    Like W2W, NASA TT competitors must earn a TT competition license, usually after years of HPDE driving and a specific "check ride" by a NASA TT director. Unlike in other groups, a NASA TT Comp license is not an "attendance award", and not everyone that tries to get a TT Comp license, will earn one. It takes thorough knowledge of safety rules, demonstration of passing kills and situational awareness, as well as some level of outright speed. There are no "slow pokes" running in TT. If you violate any of the rules you can lose your TT license also.

    Here the TT3 driver pulls offline, points by the TT1 car, not affecting the faster car's lap time

    While there is "open passing" in NASA TT, generally any on-track passing is done with a "point-by" procedure, to help avoid any chance of car-to-car contact (which is extremely rare - I have been doing this almost 3 decades and have never had contact with any car). There is simple no need to make a "pass for position" in Time Trial. Any time there is a pass in a TT session, both the car being passed and the passer tend to lose time and scrub any chance of an ideal lap. Sometimes (like in the above situation) the slower TT car ahead pulls out of the way of faster car from behind, gives a "point-by" signal, and only the slower car loses time. Ideally that's how it works.

    The grid in NASA TT is set by cars running fastest to slowest, to minimize passing

    To reduce potential traffic issues and the need for passing, NASA grids all cars based their overall best lap time, from fastest at the front to slowest at the back. There are also procedures to make sure the group stays "bunched up" a bit on the out lap, so that the fast cars at the front don't catch the slower cars for at least a few laps. Sometimes a certain amount of strategy goes into getting a lap completely clear of traffic, within the window that your tires are in their ideal working temperature.

    The minimum safety standards for TT are the same as HPDE, but many TT competitors do a lot more

    Safety requirements for TT are no higher than HPDE, but some TT competitors do choose to much more than the minimum. This option is entirely up to the competitor - you can do the bare minimum (Snell rated helmet + 3-point factory belts + roll bar in a convertible) or you can do more. The faster TT cars tend to have a 4-point roll bar (or cage), a fire bottle (or fire system), fixed back FIA racing seats, 6-point FIA racing belts, and a HANS device of some sort. Some even wear a fire suit, gloves, and Nomex underwear. Again, been at this 3 decades and have never had a car catch fire, just like to be safe.

    Winning TT can lead to track records (left), free tires (Hoosier contingencies are great), trophies and bragging rights

    There are also records kept of TT track record (by class, track and region), Regional trophies, contingencies, and National Championships. It is normal for the TT run group to have the fastest times at any given NASA race weekend. Since you only need to make one hot lap per day, you can choose to to run as many or as few laps as you want, which can greatly affect consumables and wear (tires, brakes, etc).


    So now you know what Time Trial is about, we can start looking at rules. It can get confusing, so we are going to break it down from higher level on down. NASA TT is based on one sub-set of classes within NASA. But within the NASA organization, there are four distinct W2W groups of classes, listed below. The rules for each group and sub-class can be found here.

    1. GTS
    2. AI/CMC
    3. Various "Spec" Classes
    4. Super Touring/Super Unlimited

    German Touring Series (GTS) is comprised of six classes of German (only) cars organized on power-to-weight ratios. The "Pony Car" group of classes consists the "Camaro/Mustang Challenge", "American Iron", "AIX", and "Spec Iron" - these are also power-to-weight ratio classes that include every pony car that has been produced in the United States since 1960. The "Spec Series" include classes built around a specific car or manufacturer, and include Spec Miata, SpecE46, SpecE30, Spec Z, Honda Challenge, and the NP01 prototypes.

    Each one of those three groups was limited on what cars can run in them, based on make or model. NASA Super Touring (ST) is NASA’s premiere open marque racing series, and it is open to literally all car makes and models, even prototypes and exotics. ST uses Power-to-weight ratios that are modified and adjusted using certain Modification Factors. There are currently seven ST classes: ST1, ST2, ST3, ST4, ST5, and ST6 - with SU cars having unlimited power-to-weight as the 7th class. ST encourages a wide range of builds and modifications within the power-to-weight confines to provide builders, tuners, and racers a showcase for their talent and imagination. Sounds fun, right?

    Since Super Touring is open to all car makes and models, they based NASA Time Trial off it. For every W2W class in ST there is a corresponding TT class. ST1 = TT1, ST2 = TT2, etc. For 2019 many of the duplicate TT rule sets have been eliminated, and instead just reference the ST rules.

    Obviously the safety requirements for ST cars (wheel to wheel) are radically different than the Time Trial classes, but they are otherwise the same competition rules. For 2019 there are now a corresponding 7 classes in TT (down from 9 classes in 2018 ), with the infamously hard-to-understand "letter classes" now gone completely. Remember: when I reference the ST class names, just know that the TT classes are exactly the same, just without the W2W safety regulations.


    Now that we know what Time Trials is, and which group of classes TT is based on, we can drill down more. This is where is can get confusing, and where we hope to clear up some misconceptions. We have done this before, and I wanted to update the overview we did for 2018. That is where we were discussing NASA TT rules to try to get the SCCA to adopt similar "science based" rules (to no avail).

    Reading further is still a worthwhile exercise for anyone looking to come try out NASA Time Trial - especially with the new 200TW sub-classes in NASA Texas for 2019. Here we will discuss the 13.2 Version of the 2019 Super Touring (and Time Trial) rules.

    The ST rules are broken out into two separate subsets: the STU, ST1-ST4 class rules are in one document and ST5-ST6 classes are in a second document. The biggest differences are that ST5/6 limit aero more significantly, engine swaps are a bit more restricted, and Hoosier A7s are not permitted.

    TTU - Unlimited. No minimum weight, no max power. Just about anything goes!
    TT1 - Adjusted Power-to-Weight ratio of 6:1 or higher, no penalty for aero
    TT2 - Adjusted P-to-W ratio of 8:1 or higher, no modifier for aero
    TT3 - Adjusted P-to-W ratio of 10:1 or higher, modifier for non-stock aero
    TT4 - Adjusted P-to-W ratio of 12:1 or higher, modifier for non-stock aero + more restrictive aero and tire restrictions
    TT5 - Adjusted P-to-W ratio of 14:1 or higher, more restrictive aero, suspension, engine, and tire restrictions
    TT6 - Adjusted P-to-W ratio of 18:1 or higher, more restrictive aero, suspension, engine, and tire restrictions + no forced induction


    As you can see these classes progress along finite jumps in P-to-W (with a bigger jump from ST5 to ST6). There is more than just Power-to-Weight limits, of course. NASA bases the classes on four critical, measurable variables that affect lap times:

    1. Weight (measured with driver and fuel, as the car comes off track after a session)
    2. Power (average horsepower measured in a specific way on specific chassis dynos)
    3. Tire width and Compound (tire widths are verified by 4 measuring templates)
    4. Aero Upgrades (with some limits and/or modifier for some classes)

    There are some smaller limitations, modifiers, and bonuses in all classes, but those 4 aspects are the main limitations for all classes. This way an ST/TT competitor can choose to focus on what they feel best suits their car/budget/tracks, and some mods can be traded for others using the a Power-to-Weight modifier system.

    continued below
    Last edited by Fair!; 01-02-2019, 11:31 AM.
    Terry Fair -
    2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
    EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev

  • #2
    Re: 2019 NASA TT Rules Overview + 200TW Texas Region Classes!

    continued from above

    These four aspects listed above can all be measured directly, without having to infer things, like "power" interpolated via antiquated formula involving engine displacement. Without car weights based on some semi-arbitrary factory listed "curb weight". Without having to trust printed sidewall tire size numbers, which are often in error. And without aero rules based on technology from the 1960s.

    These things combine to create two dominant ratios, Power-to-Weight and Tire-to-Weight.

    Thus, your car's weight is measured at NASA events, and often. Weight is always measured with driver and fuel, as you come off the track. NASA weighs cars after many, if not all TT sessions.

    Taking direct weights of car + driver happen often at NASA TT events

    If your car weighs over your declared minimum, no problems. If your car weighs under your declared minimum weight, your times get DSQ'd. We often "declare" a weight we know is about 5-10 pounds higher than we would ever run with any fuel load - to account for any possible extra laps we might run than normal. Digital scales are very accurate, and these are available during tech inspection periods (the day before most events) and throughout any other time in a NASA event weekend. Plus most race shops have digital scales on hand for setup, so this isn't an unusual burden.

    All NASA TT cars need to be dyno'd to complete their classing sheets - dyno verification can happen during race weekends, too

    Similarly, a chassis dyno is used to directly measure power output. Dyno testing during a weekend is rare at Regional events but common at NASA National events. If your car dyno's over your declared "average power number" at an event, you will lose times from your session. All cars must have a dyno test done before competing with NASA, which helps class their car correctly.

    Chassis dynos number in the thousands across this country and are often found at shops located right at road courses, so again - this is not some impossible technology to comprehend or find. We typically dyno test all of our TT cars at least twice a year, to act like an annual "check up" on the engine. An erratic, or lower dyno result could mean there are potential problems to address, but an identical test from year to year indicates nothing changed - it is a "healthy engine".

    Likewise aero devices are directly measured, with rules that close loopholes in interpretation of poorly written rules. This clears up confusion, and in some classes aero is restricted or optional.

    Last but not least, tire width is limited or carry graduated bonuses for running smaller sizes in each class. Again - you can choose to run a narrow or wide tire (within some set limits for ST4-ST6), and gain a bonus elsewhere for running smaller sizes. And these sizes are now measured directly, removing the "ringer" tires that "run big" in some brands and models. These 4 tire measuring tools are available to purchase so racers can check their mounted tire widths on their wheels before they get to the track. Simple and effective.


    Since NASA ST/TT classing involves "calculations within calculations", NASA created an online configurator, and it actually works very well (see below). If you are new to this just click that link and start inputting data from your car and it spits out your class.

    NASA ST/TT Class Configurator:

    But there are some other, smaller modifications and limits within the 6 ST/TT classes. We feel it helps to understand the fundamentals of the various "bonuses and penalties" (modifiers) to the car's overall Power-to-Weight ratio, to be able to maximize your build for maximum performance. If you are new to NASA TT you can probably skip this part, but herein lies the secrets to TT classing.

    These are two pages of the ST1-ST4 rules (below) that outline the main modifiers for ST1-ST4 (ST5/ST6 are slightly different). Looking at the those listed modifiers, we will try to snag as many of the bonuses and minimize penalties to maximize the competitiveness of a particular build.

    For instance, we often add ballast to the car to be able to run in a higher "competition weight bracket" to gain a P-to-W bump. Our 2018 Mustang runs in TT3 above 3900 pounds to gain a big +0.6 bonus in P-to-W. Sometimes you can move down 10mm in tire size and gain a decent P-to-W bump as well.

    It is nearly impossible to "balance" a street tire vs an R-compound. Their performance difference is too great

    Tire compound can also bring a penalty or bonus, but we argue that is nearly impossible to balance a street tire to a R-compound in the same class (more on that below). Running a non-DOT racing slick vs a Hoosier A7 is only -0.5 penalty, but those tires are very close in performance. Whereas running a 100T or higher treadwear street tire is only a +0.5 bonus, which is hardly an equalizer to an A7.


    To keep the spending potential down in the lower classes, there are some optional aero rules in ST3, ST4, ST5, and ST6. In these 4 classes you get a sizable P-to-W bonus for running the OEM aero (based on the "Base Trim Model" of your car). You can look at this as a penalty (and a spending deterrent) if you want to run a big wing and/or splitter in these classes, too. This is one of those variables you can juggle to make the car suit your driving style, budget, desires, and the tracks you frequent.

    We ran TT4 with the "non-OEM" aero penalty, but picked up a lot of downforce

    We made this BMW 330 into a TT4 car late in the 2017 season, choosing to run the maximum allowed rear wing and front splitter per the class rules, with the penalty that imposed to our P-to-W ratio. This gave us higher cornering speeds at faster tracks that we run, like NOLA, COTA and the like. When you run at a track that has high straight away speeds, higher than average speed corners or esses, aero upgrades to add downforce enter the calculation. The aero rules have since changed for TT4 to be a bit more restrictive than what we ran on the car above.

    Lower ride heights, low hanging front splitters, and giant wings don't work well on your daily commute!

    Optional aero devices are less attractive on a dual purpose street car, however, so this "dual use" side of things can come into play. If you don't want to take the optional aero hit in these classes, it is best to take advantage of other optional upgrades - perhaps to power, weight, or tire width/compound.

    In ST1/ST2 there is no P-to-W break for OEM aero and most of these cars DO have wings, splitters, diffusers and canards. Its not required, of course, but at the faster end of the grid these "spending limit" type of options do not exist. The faster ST3/TT3 and ST4/TT4 cars are going to be seen with aero as well.

    The new TT5 and TT6 classes have even bigger penalties for running aero, so optional aero will be less prevalent in those classes. These are meant as cost controls, and they seem to work.


    In an effort to remove the "You have to be on Hoosiers!" stigma that has evolved in NASA Time Trials, we have sponsored an experimental series of sub-classes for NASA Texas Time Trial built around a 200TW tire. This press release was sent out on Dec 21st explaining the Texas Region 200TW championship that they agreed to let us try. To encourage the class, Vorshlag will provide trophies for the Street Tire competitors.

    Press Release:

    Back at the beginning of NASA TT, some competitors could win classes and even set class track records on street tires (we did a few times), but that quickly changed. It wasn't long before more top level NASA TT entries moved to dedicated R-compounds and non-DOT slicks.

    This EVO X and this BMW both took wins and/or set TT records on street tires back in 2006-2008

    These "tire wars" have escalated, and unless you can afford to buy or win new contingency tires every time out, you have to budget $300-1000+ per weekend to stay on sticky R-compound tires.

    Tire costs have quickly become largest part of most Time Trial competitors' budgets. I have seen this first hand in 2018, running both a 200TW Bridgestone as well as a Hoosier A7, in roughly the same size, on the same car (see above). The $2000 set of Hoosiers were corded during the second weekend, but the RE-71Rs still have tread life (and speed) on weekend #9! Many people have seen this "Race tire war" play out, and have opted to switch to longer wearing street tires - often with other series.

    By 2013 we were bringing new "sticker" sets of Hoosier A6 tires, to help knock down track records

    Since those days, the number of tire options in the 200 treadwear segment of tires has grown tremendously - tires which last a lot longer than sticky R-compounds. This growth has been fueled by endurance racing groups, autocross classes, drifters, and other Time Attack groups building classes and entire series around these longer wearing street compound tires. We have been hearing from a lot of folks about tire costs, and were working on a way to bring 200TW to NASA TT. We worked with Will Faules of NASA Texas to create this experimental series of regional classes built around a 200TW limit.

    Optima / USCA was one of the groups that built their whole series around 200TW tires - and it works

    In the new NASA Texas 200TW Championship, cars will compete in the existing TT1 to TT6 classes, but will also be scored during the event as a ‘race within a race’ for cars entered on and declaring the use of 200 UTQG rated tire. For example; a driver will still compete in TT1-6 but will declare in the morning meeting to be running on a 200TW tire. Tires will be verified by the NASA Texas Time Trial Director. It will then be noted on each results page during the day which cars are running in the 200TW sub-class. Regional season points will be awarded for these Street Tire sub-classes. Vorshlag will be presenting trophies for the podiums of these classes for every event as well as the 2019 Street Tire Season Championship.

    This set of experimental 200TW classes should bring in new competitors and give existing TT folks a new option to compete on tires that could save them thousands of dollars per year. We are excited to see the outcome in 2019! If you are in or near Texas we welcome you to reach out and try to be a part of this. You will still need to earn a NASA Time Trial license, of course.

    Thanks for reading,
    Last edited by Fair!; 01-02-2019, 11:30 AM.
    Terry Fair -
    2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
    EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev