In NASA Time Trial competition, anything goes, from prototype racecars and converted production cars to the current crop of electric cars. Weight-to-horsepower ratios make for fair classes and lots of creative freedom to build the car you want.


If you’re thinking about graduating from HPDE to Time Trial (TT), we’ve put this feature together to give you an idea what to expect and help you determine what direction you might want to take. NASA TT provides a venue for spirited on-track competition with a high degree of safety and convenience. NASA TT allows qualified individuals to compete in a “best lap time” format in a prepared car in advanced level open-passing sessions, and bridges the gap between NASA HPDE4 and wheel-to-wheel racing.

Class Description

NASA Time Trial is an automobile road course competition series focused on time trial-style competition, and shall function as an advertising and marketing tool for the series sponsors, the independent sponsors of each team, as well as the official sanctioning body of the series.

Eligible Makes and Models

Virtually anything from Acura to Volkswagen in race or street trim is eligible to compete in NASA TT. There are the usual classes for internal-combustion-engine cars, and now EVs also have a Time Trial class in NASA.

Donor Prices and Availability

Because you can run anything in NASA TT, donor prices to build a new Time Trial car range from several hundred dollars to several thousand. Daily driven street cars also are eligible to compete in TT. From shop floor to showroom floor, all cars are welcome.

Engine Specs

There are no engine specs, per se, but according to the rules, “the Adjusted Weight/Power Ratio for each vehicle will be calculated based on a simple competition weight to average chassis dynamometer (Dyno) horsepower ratio (Wt/Avg HP), followed by the adjustment of the resulting ratio by adding to, or subtracting from it, based on the list of “Modification Factors.” Competition Weight is defined as the minimum weight of the vehicle, with driver, any time that it competes in a qualifying session or race. Average horsepower calculation (Avg HP) is defined in Section 7.2.”


All vehicle weights will be measured to the tenth of a pound (xxxx.x), and then rounded off to the nearest pound for all calculations. Any weight ending in “.5” (xxxx.5x) NASA Super Touring (ST1-4 & SU) Rules 2020 v14.1 Page 13 of 28 will be rounded up or down to the benefit of the competitor. All horsepower measurements will be rounded off to the nearest whole number, and any number ending in “.50” (xx.50x) or less will be rounded down. Any “Adjusted Weight/Power Ratio” calculation ending in “.995” (xx.995) or greater will be rounded up to the benefit of the competitor.

TT1 = “Adjusted Wt/HP Ratio” equal to, or greater than, 6.00:1
TT2 = “Adjusted Wt/HP Ratio” equal to, or greater than, 8.00:1
TT3 = “Adjusted Wt/HP Ratio” equal to, or greater than, 10.00:1
TT4 = “Adjusted Wt/HP Ratio” equal to, or greater than, 12.00:1
TT5 = “Adjusted Wt/HP Ratio” equal to, or greater than, 14.00:1
TT6 = “Adjusted Wt/HP Ratio” equal to, or greater than, 18.00:1

Class Calculator

Fuel Required

Nitrous oxide use is prohibited. Pre-existing tanks must be removed. Methanol/alcohol-water injection is permitted provided that the mixture does not exceed 50% alcohol by volume. Methanol is not permitted as a fuel. (See CCR 15.19 and 18.3)

Average Cost to Build Car

Because the cars in TT are so varied and because some of them are street driven, there really is no average cost. Figure $10,000 to $15,000 for a race-prepped TT5 or TT6 car. From there, prices rise with speed and horsepower.

Average Cost to Buy Built Car

You can buy anything from a used first-generation Spec Miata for $5,000 to a $250,000 prototype. Your budget will determine how fast and powerful a car you get.

Typical Modifications

That’s the beauty of Time Trial. You choose which modifications work best on the car you have chosen to build. The rules allow for freedom and creativity.

Cost Analysis

Average cost to run a weekend — $500 to $1,000

Consumables Prices

Tires, size, brand and prices
Because wheels vary widely with car choice, figure $192 for 205-50-15 Toyo Proxes RRs to $315 for a 275-35-18 Proxes RR.

Brakes, brands and prices

$150 to $250 depending on the car you choose.

Available contingencies

Hawk Performance, Maxxis Tires, Hoosier Tires, Hankook Tires, Spec Clutches, NISMO, Mazda Motorsports.

Factory Participation

NISMO, Mazda Motorsports.


– Build whatever car you want
– Variety of competing cars
– Lots of creative freedom within the rules
– Lots of tire choices available


– Competitive cars can get pricey
– Electric cars are coming on strong!

Rulebook Highlights

TTEV (Electric Vehicle) Classing
TTEV is an open class for Tesla Model 3, Tesla Model S, Porsche Taycan, and other performance electric motor vehicle models as added in the future. HPDE technical safety inspection rules shall apply. No modifications are permitted to the factory motor, software, EV related safety features, or batteries (other than replacement of the 12-volt lead-acid accessory battery). All vehicles must use either tires with a UTQG treadwear rating of 180 or greater or the Toyo R888R. Note that future additional classing rules and/or Modification Factors may be added (although none are expected for 2020).

TT Classification Forms

In order to accrue points or compete, each year/season, all NASA TT competitors (except TTU competitors) must submit a current year, completed NASA ST/TT Car Classification Form (and certified Dyno report) to the Regional TT Director prior to having lap times count toward competition. Once a form has been submitted during a season, if there are no modifications to the vehicle that would change the form, a new form does not need to be submitted at subsequent competitions.

Driver Requirements/Licensing

A NASA TT license can be revoked for a variety of reasons, some of which include: giving false information on the application, failure to comply with the rules, unsafe driving, high incident count (spins/offs), car contact (with objects or other vehicles), and unsportsmanlike conduct on or off the track. Licensed racers participating in NASA TT that commit any of the above infractions may be subject to suspension or permanent ejection from NASA TT competition, as well as revocation of their NASA Competition Race license.

Timing Format

NASA TT competitors will be scored on a basis of their fastest lap time during an event day. Therefore, a regional NASA weekend would generally count as two separate event days, with points and awards for each day. NASA TT competitors will be timed continuously in each designated TT run session that they participate in (which could be a combined HPDE 4/TT run session or a TT-only run session). The sessions are typically between 15 and 30 minutes long. The fastest lap time from all of the sessions will be used as the basis for his/her score for the event. The first run session of the weekend will not count for TT competition, and will function as a warm-up practice session. The first session of subsequent days will count toward competition.

What Racers Say

Casey Jones, TT2, NASA Texas

“I wanted to get faster and it seemed to me that many HPDE drivers were simply content to “put in laps” and have a good day at the track. While there was nothing wrong with that, I just wasn’t content. I saw the Time Trial groups and spoke with them, and it’s an entirely different mindset. Every single one of them wants to get faster and are all more than willing to help their own competitors to get faster. That really was the mindset that I was after.

It’s a different type of competition than wheel-to-wheel racing, and I’ve done both in one NASA weekend, but Time Trials always sticks with me. With racing, it’s stringing together a bunch of good laps to stay ahead of your competition, but with TT, it’s aiming for as close to perfect as you can get, and oftentimes not knowing if your competitors are running any faster or not. It’s all up to how close to perfect you can get.”

Dennis Clavette, TT3, NASA Great Lakes

“Racing is an entirely different beast and requires a bit more strategy and tactics than TT. However, I have stopped short of prepping my own car for racing for a few reasons. Racing is a significant jump in time and money as well as being harder on the car itself. On a typical TT weekend, I may only run two sessions of 2-3 laps on each day. I am running the car full out during these laps and I just think it’s tough to ask the car to do this for 2-3 20-plus minute race stints per weekend. I know others do, but if I were to race this car, I would certainly dial it back a bit for long-term reliability. Also, the cost of racing is much higher in my estimation because you’re going through a lot more consumables and hitting maintenance milestones much sooner than in TT. That being said, I just love to compete and TT is a very cost effective way to scratch that itch.”

Samed Rizvi, TT5, NASA Northeast

“I think TT5 in NASA Mid-Atlantic is the largest and most competitive in the country. After every weekend, we all share our data so we all know what each other is doing. We also have a great ST5/TT5 group chat with NASA Mid-Atlantic, Great Lakes, and Northeast drivers. In between making fun of each other, we share what we are doing with our cars and answer questions. We all share everything so there is no need to really tabs on anyone.”

Dan Westerwick, TT3, NASA Great Lakes

“Racing sounds like fun, but unfortunately I don’t think it’s affordable with my car. With the Time Trial format, I only need to drive a few laps per day, and that allows me to limit consumable expenses if I’m on a budget. I realize this reeks of the sunk-cost fallacy, but there is a large initial cost of building a new car or buying one that is already race-prepped.”

Robert Porter, TT5, NASA Mid-Atlantic

“Honestly, I’m friends with most of my regional competitors and we all paddock together and hang out, so it’s really easy to keep tabs on them. The TT5 champ, Samed, and I run in the same region, so we see each other all the time and always share notes. The truth is Samed really helped me become a better driver, and I owe a lot of my success to him.

Even when we go out of region, we usually go as a group of at least four or five, and people I have met outside of my home region are so friendly that I usually leave with a few new friends. Social media is a great way to stay connected to those new out of town friends and stay up to date on their progress and success.”

Dennis Bakun, TT3, NASA

“While I’m competitive by nature and would really like to try wheel-to-wheel at some point, the satisfaction I get from going out on track and extracting the most from my car any my driving during each session will keep me coming back to TT. As our rules set is further refined to encourage more competitors to run with us, hopefully we’ll see more racers crossing over to TT during future events, so that we can run larger, more competitive fields, and continue to grow into better, faster drivers.”

Lapping Videos

Images courtesy of Redlinephoto, Downforce Media and Juha Liev

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