FS/AA vs FS/XX
 

I was checking out the entry lists for some of the NHRA national events and saw some guys entered in FS/XX. What's the difference between FS/ XX and FS/AA?

Re: FS/AA vs FS/XX
 

FS/XX is the class designation for the Factory Stock Showdown cars which run in their own separate eliminator. FS/AA is the designation for the cars that choose to run in Stock eliminator. The Factory Stock Showdown cars that don't qualify for the eliminator are not allowed to run in Stock eliminator. A FS/XX car can run in FS/AA by adjusting weight to meet the FS/AA weight break which is 5.50 - 5.99 lbs per factored HP. Conversely a FS/AA car can run in FS/XX by adjusting weight accordingly. The Factory Stock Showdown is contested at 8 National Events this year.

Re: FS/AA vs FS/XX
 

Thanks superfan. But, they are entered in stock, why are they not entered in the showdown?

Re: FS/AA vs FS/XX
 

For example. Cody Phillips is entered in FS/XX at Bristol, in stock. There is no FSS contested at this race. So why is he entered in stock as an XX car?

Re: FS/AA vs FS/XX
 

Probably about 350 grand a season.....

Re: FS/AA vs FS/XX
 

When he goes through tech, he will tech in as a FS/AA.

Re: FS/AA vs FS/XX
 

There was talk on here about different Shootout superchargers and maybe a few other things in a post, are they allowed in Stock eliminator?

Re: FS/AA vs FS/XX
 

The engine combo's currently used in the shootout are "legal" in stock but many of them are rated at a hp that put the car over the maximum allowed weight of 3,600lbs for an SFI25.5 7.5 second cage. for example the 2016-2018 COPO were delivered with a 350 with the whipple rated at 580 hp (currently factored to 617), but the rulebook also allowed a 590hp version(currently factored to 630hp) the difference between the two included superharger puller size, rocker ratio difference, and some valvetrain stuff. In the 2019+ COPO's they come with a 600hp rated 350 with the magnuson, or there is a 630hp verison also in the rulebook, again just different pulleys and rocker ratios.

With the current weight break of 5.5 in FS/AA once a combination is rated over 623hp the car will be over 3600lbs, the specs for the 7.5 second cage is limited to cars under 3,600lbs. Based on the rules you can run the higher rated shootout motors in FS/AA but it would put you over 3,600lbs so you wouldn't be permitted to make a run faster than 8.5 seconds because the cages aren't certified to 7.5 seconds at those weights.