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Project Update for February 2, 2013: This thread update covers the first 2013 NASA Texas race weekend we attended in the red Vorshlag 2011 Mustang GT. This January event is always held down south of Houston, but is sometimes plagued by poor weather (rain or cold). I was going to skip this event, but peer pressure worked and pushed both me and Amy to attend. I'm glad we did - the weather turned out to be extremely nice and we had a total BLAST running the red 2011 GT in the new TT3 class.

I will back up a bit and talk in more detail about the classing tweaks that NASA made for 2013, which I hinted at in an earlier post in this thread. This is the first significant classing change that I have noticed in TT since we started running this series in 2008. It looks bigger than it really is, as most of the changes were mostly to the class letters/nomenclature, but there were some substantial changes to TTA (now TT3).


2013 NASA TT Class Updates - Letter vs Number Classes

None of what is written below is official or approved by NASA, just our overview and interpretation of their rules. Don't take our word for it - read the rules yourself if you want to learn how to class your car for NASA TT. These rules only span 54 pages and only parts of that will even apply to a given entry. If you get mired up in the classing though, don't worry - we're here to help. Matt and I at Vorshlag have helped class hundreds of new folks into NASA TT. We have our own "class configurator" that is normally more up-to-date than the one's NASA makes. Shoot us an e-mail and we can help get your car classed, free of charge: info (at) vorshlag (dot) com, with a subject of "Help with NASA TT Classing". We can help with SCCA Solo classing as well, but that might involve substantially more tortured logic.

2013 NASA Time Trial Rules: http://www.nasaproracing.com/rules/time_trial_rules.pdf

NASA classes each Time Trial car into a "base class" and gives it a "base race weight with driver". Each base class has a "base tire width". Some cars have handicap points in their base class, denoted by one or two "stars". One star = +7 penalty points and two stars = +14 penalty points. Then modifications each cost "points", and you get 19 points to play with before you bump up a class. Running below your base race weight costs points (but heavier gains you points back). Running more tire width than your base size costs you points (but narrower gains you points back). The points for parts eats up most of your allotment, but whatever you change you can never violate the power-to-weight limit for a class. It sounds confusing, and it kind of is... but only because it is so unconventional. But this type of classing is also liberating, fun to explore, and competitors can "bench race" set-ups with different mods to play with their 19 points in class. Or you can go buck-wild and use more than 19 points and bump up a class... then you get a total of 39 points (or more) to play with. Make sense? You can keep adding mods or lowering weight or adding power to keep your car at the competitive limit for each up-class jump you make. This is how the new "letter" classes work (TTB-TTF)


Vorshlag built entries for NASA TTD and TTA classes.

Our Intro to NASA Time Trial article, circa 2008: http://www.vorshlag.com/tech_timetrials.php

This means you can have a Miata with wild aero, sticky Hoosiers, and a supercharger racing against a nearly stock E46 M3. And oddly enough, it works, as there is always the power-to-weight element... measured horsepower and measured weight reign everyone in. There are not "categories" to jump up, and anything can eventually be classed with almost anything else, if a given car gets modified radically enough.



In 2012, beyond TTA were the top three classes which were always strictly power to weight based, with no more points to play with. I now call these the "number classes", but in 2012 they were TTS, TTU, and TTR. There are "modifiers" you can exploit, to get you a little more power or a little less weight, if you have say... a 4 door vs a 2 door, or use a 275mm or narrower tire, etc. Otherwise it is strictly power to weight based. When we first started racing our 2011 Mustang in TT (see above), it was in TTB, but since it came with the Brembo brakes (+2), no decklid spoiler (+4), and the CS front lip (+3), we had very few points left to use. If we had added R compound tires and any exhaust mods the car would be easily into TTA and then even into TTS on points alone, due to the SCCA class allowances and rules we were focusing on (STX then ESP). We ran a few TT events with our STX set-up and it was difficult to manage the the narrow-ish street tires (just like it was in autocross!), but our ESP set-up with 315mm Hoosiers or Kuhmo race tires worked pretty well, but bumped us clear up into TTS. We almost won the November ECR TTS class, until a TTU car bumped down their power and ran quicker and beat us. Oh well, we were still too heavy and/or underpowered for TTS, nowhere near the power to weight limit. It was what it was... we were building our car around SCCA rules and letting the TT classing fall where it may. Other than adding the transponder, a brake pad and rear aero change, our Mustang was still set-up around ESP autocross rules for most of the 2012, even when run at NASA events.



Let's look at the old vs new classes in NASA TT, of which there are still 9 classes total. Nine classes, not 427 classes, like in SCCA Solo. Just sayin'. Anyway, most classes had little to no change other than a more clear naming style (numbered classes are power to weight only, letter classes are still points based). Here are the changes from 2012 to 2013, mostly affecting just one class...

NASA TT Classing - Name and Ratio Changes
2012 ... 2013
TTR -> TTU (Unlimited Wt/Hp)
TTU -> TT1 (5.50:1 Wt/Hp)
TTS -> TT2 (Was 8.70:1 Wt/Hp but went to 8.00:1 Wt/Hp)
TTA -> TT3 (Was 8.70:1 Wt/Hp but went to 9.00:1 Wt/Hp) For TT3 only, non-OEM Aero is a 0.5 modifier (in effect requiring 9.50:1 Wt/Hp).
TTB - 10.25:1 Wt/Hp
TTC - 12.00:1 Wt/Hp
TTD - 14.25:1 Wt/Hp
TTE - 16.50:1 Wt/Hp
TTF - 19.50:1 Wt/Hp

As you can see, before there was some overlap with TTS and TTA both having the same 8.7:1 power to weight ratio. But TTA - TTF were still all "points" based as well as power to weight, whereas TTS was only power to weight. Modifications in TTS were relatively unlimited, with those modifiers for certain limitations. So in reality TTS and TTA had very similar on-track performance. Now with the new TT2 and TT3 ratios and the removal of points based modifiers, they have effectively made the difference between TT2 and TT3 more significant and it creates more places to run your car, and more time difference between the two classes.

In order to keep it interesting in TT3, they also let you choose between a 9:1 and a 9.5:1 ratio. If you keep "stock aerodynamics" you can go with the more attractive 9:1 ratio, but if you want wings, splitters or other aero changes you get the 9.5:1. Still lots of room to tweak and play ... and bench race. And since we are in TT3 now, we get to strategize and play with more aero vs more power. Kind of looking forward to testing this.



As you saw in my last "mini-post", we went with TT3 and we chose the 9.5:1 ratio with alternate aero. Hard to give up the big rear wing and front splitter after you've tried it. We had to add a few pounds, but with our most recent dyno of 424 whp, and the +.6 modifier for running over 3750 pounds with driver, we were able to get a race weight of 3775 lbs, with driver. Here's the math.

3775 lbs / 424 whp = 8.903 pounds per hp... +.6 modifier (for running over 3750 lbs) = 9.503:1

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