NASA rules

[Bill Waters]

Just a quick question for those familiar with the weight:hp classes and modification factors in ST1/ST2/ST3; I can't find the answer to my question in the NASA rules. (It may be so straightforward that no explanation should be necessary!)

These classes fall into the 5.50:1, 8:1 and 9:1 weight to power groups. If modifications increase or decrease these ratios to give a competitor his final "score," what is the implication of that? I can't find ballast penalties to equalize, as in the Challenge series. Is it just that one's final car prep leaves him with a modified ratio, and that, if he is beneath the breakpoint between classes, he must go to the next class and is otherwise OK?

Thanks for any help.

Bill

[Gordon Levy]

ST2 is a really good class for the car. You can also do ST3 but I think it would be more competitive in ST2.

[Jim Schenck]

Bill,

You add up all of your modification factors like tires, weight range, aero mods, etc, and it will give you the power to weight that your car needs to be over to be in each class. If you are just over powered or underweight you get bumped up into the next class, however adding ballast, intake restrictors, or narrower tires can get you back down to just under the maximum in a lot of cases. If you are going challenge legal then my personal opinion is run 245 hoosier a7s and ballast up to the next weight break to run ST2, however you can also trim down to ST3 where there are harsher aero penalties to have to compete against.

[johngeorge]

Bill,

Here is the math I use based on 2016 ST2 rules. you start at 8.0:1, then add/subtract deductions.

min weight of 2600lb = -.1 weight factor
250-275 DOT = +.3
aero - vehicle specific = -.2 (FFR cobra with aero)
(raw weight/hp = 8:1)
So, I can have 325HP (2600/8)


min weight of 2600lb = -.1 weight factor
245 and smaller = +.7
aero - vehicle specific = -.2 (FFR cobra with aero)
(raw weight/hp = 7.6:1)
So, I can have 342HP (2600/7.6)

[mhoward1]

Similar I am going for ST3:

min weight of 2600lb = -.1 weight factor
245 and smaller = +.7
No Extra Aero
(raw weight/hp = 8.4:1)
That gives me 309 WHP.

With the upgrades I am at 321 WHP, so just a ~3% throttle stop should do the trick, or tune the ECU.
So very little change from Challenge rules gets me in ST3.

[Gordon Levy]

Take 4 degrees of timing out will do the same thing.

[mhoward1]

Take 4 degrees of timing out will do the same thing.

What would be perfect would be a smart tune that cut timing out at 4500 RPM in forth gear only.

Want a challenge?

BTW, this is one of your builds.

[Gordon Levy]

Which one would that be?

[mhoward1]

Which one would that be?

Spencer Sharp's old car. The red and silver one

It's been a great car, and I somehow even managed to even win a couple of regional championships with it

[Bill Waters]

Thanks, guys; your comments clarify things a great deal. Now to build & see how it turns out! Probably be ordering car tomorrow; am building engine and have TKO, clutch, etc ready to go.

Appreciate the response.

Bill

[Gordon Levy]

Nice Howard, how do you like all the intrusion protection we put in?

[Gordon Levy]

Bill, Call me about set up and brakes. There is a ton we have figured out in all the years of racing these things.

[mhoward1]

Nice Howard, how do you like all the intrusion protection we put in?

It's all been great. The car has been dead reliable and performed as expected. I just wish the driver was as good.

[Bill Waters]

Bill, Call me about set up and brakes. There is a ton we have figured out in all the years of racing these things.

Will do, Gordon; am ordering car tomorrow; I'll call you in AM.

Bill