S197 Mustang in SCCA Solo: STX vs STU vs ESP?

[Whiskey11]

In that case you'd likely run 285 RS3s in STU, or run 305+ A7s in ESP. The time difference (on a 70 second course for an STU car) is:

ESP
0.849
69.753
-0.247

If that ^^ is true then the most competitive class for our cars IMO is ESP. Not sure if there were any recent changes to STU class though.

PAX is absolutely, positively, the worst way to compare classes as ST cars lose less time on asphalt to SP cars because Hoosiers don't gain as much grip and ST tires don't lose a whole lot on that surface.

To add insult to injury, STU's PAX is even harder because of the dominance of AWD cars which benefit even more from asphalt vs concrete surfaces over Hoosier shod cars.

To show what I mean, Brian Peters in STU at Nationals ran a 122.134 combined time. Billy Brooks ran a 117.905 in ESP (in a WRX...). PAX would require Brian Peters to run a 118.323 to PAX the same as ESP. Not going to happen nor has it EVER happened at Nationals.

If you go to the Data-Derived Autocross Index (DAX) setup the index for STU is .834 and ESP is .852. This would have required Brian Peters to run a 120.450 to PAX the same as ESP. That index uses only National Tour and Nationals results to determine the factor and is a lot more fair for comparing cars.

That all ignores the reason why we requested to be moved to STU. That was to show that wider wheels and tires would not make these cars overdogs in STX. Unfortunately CAM popped into existence and has given a healthy dose of "sit on our hands until that shakes out" to the STAC and live axle allowances. I think we were lucky to get the brackets and lower control arms but I think we presented an extremely healthy and strong case to them.

With all that in mind, I remain hopeful. My car has about 100lbs of weight to come out, maybe a hair more, some power, a good diff (ordered!) and the wider wheels and tires for STU to go and had I ran .75 seconds per day (with all of that done) faster than the local I normally run against, I would have placed 9th just outside the trophies. Now I don't know if there is .75 seconds between all of those mods, or more, or less, but I remain hopeful that it all adds up because I DO think these cars could trophy in STU with the right driver (read: Not me, I'm a hack).

 

[NDSP]

I've really enjoyed running MAM, because it is basically a class for S197 mustangs and Newer Camaros. It gives me a much better feel for how I'm doing as a driver, considering I'm running very similarly prepared cars to mine. That being said, the first place MAM car would of placed 6th out of 7 in STU, and he is a quick racer. We still need more tire to be competitive in STU.

 

[sheizasosay]

How does the smaller tire affect the AS setting? What happens when you go overboard with anti-squat?

Geometrically nothing changes in respect to the AS% no matter how tall or short the tire is.....just incase that was what you had in mind when you asked Modernbeat. Youhave less tire=less grip. Add AS%=increase rear grip on throttle. At least that's the way I take interpret it.

 

[Arustik]

PAX is absolutely, positively, the worst way to compare classes as ST cars lose less time on asphalt to SP cars because Hoosiers don't gain as much grip and ST tires don't lose a whole lot on that surface.

To add insult to injury, STU's PAX is even harder because of the dominance of AWD cars which benefit even more from asphalt vs concrete surfaces over Hoosier shod cars.

To show what I mean, Brian Peters in STU at Nationals ran a 122.134 combined time. Billy Brooks ran a 117.905 in ESP (in a WRX...). PAX would require Brian Peters to run a 118.323 to PAX the same as ESP. Not going to happen nor has it EVER happened at Nationals.

If you go to the Data-Derived Autocross Index (DAX) setup the index for STU is .834 and ESP is .852. This would have required Brian Peters to run a 120.450 to PAX the same as ESP. That index uses only National Tour and Nationals results to determine the factor and is a lot more fair for comparing cars.

That all ignores the reason why we requested to be moved to STU. That was to show that wider wheels and tires would not make these cars overdogs in STX. Unfortunately CAM popped into existence and has given a healthy dose of "sit on our hands until that shakes out" to the STAC and live axle allowances. I think we were lucky to get the brackets and lower control arms but I think we presented an extremely healthy and strong case to them.

With all that in mind, I remain hopeful. My car has about 100lbs of weight to come out, maybe a hair more, some power, a good diff (ordered!) and the wider wheels and tires for STU to go and had I ran .75 seconds per day (with all of that done) faster than the local I normally run against, I would have placed 9th just outside the trophies. Now I don't know if there is .75 seconds between all of those mods, or more, or less, but I remain hopeful that it all adds up because I DO think these cars could trophy in STU with the right driver (read: Not me, I'm a hack).

Interesting. Thanks for the insight, I've honestly never heard of DAX, until now. I guess PAX is still important for me because we run on asphalt. R-Comps make a major difference here and PAX is pretty dead on in this case.

Not gonna lie, I don't know anything about running on concrete.

 

[Thinkkker]

Whiskey,
What is the most recent weight on you car? As of now, my car has gained some *hitch and such*, but in full garb the car sat at 3200.

 

[Norm Peterson]

Geometrically nothing changes in respect to the AS% no matter how tall or short the tire is.....just incase that was what you had in mind when you asked Modernbeat. Youhave less tire=less grip. Add AS%=increase rear grip on throttle. At least that's the way I take interpret it.

The AS% does change a little with tire height changes, but probably not by enough to be concerned about. The CG and the SVIC both drop by the same amount (let's say by ~1/2" when you go to a 26" tall tire), but when you project the line through the rear contact patch and the SVIC forward to the front axle line the height of that line at the front axle drops by more than 1/2" when the SVIC lies between the axles. AS% then drops slightly.


Norm

 

[jmauld]

Geometrically nothing changes in respect to the AS% no matter how tall or short the tire is.....just incase that was what you had in mind when you asked Modernbeat. Youhave less tire=less grip. Add AS%=increase rear grip on throttle. At least that's the way I take interpret it.

A shorter tire doesn't necessarily equal "less tire", does it?

 

[jmauld]

Whiskey,
What is the most recent weight on you car? As of now, my car has gained some *hitch and such*, but in full garb the car sat at 3200.

What have you done to get down to 3200? Which trim level did you start with?

 

[claudermilk]

I do indeed have the TCA022 LCA's. As to how they are allowed, it is the same LACK of language that is present in the "Lateral locating device" rules that allows us to run PHB's with rod ends and watts linkages with rod ends. Basically the rule states "You can repalce it" and then doesn't restrict with what so it is 100% open. Apparently in the SCCA the bushing rule is not overruling all other modifications which means it only applies to parts that you can't replace (such as the LCA's on a live axle car in 2014, you couldn't run a spherical but only a cylindrical rubber bushing in the stock arms).

Mark A of the SEB basically confirmed the intent was to leave this rule completely open like the lateral locating device wording. Maybe DILYSI Dave can confirm or deny that intention but that is the way it is worded.

I wont speak for BMR but I think the biggest difference is the bar stock used is thinner on the TCA032

OK, thanks. I wasn't completely sure with the wording and didn't want to run afoul of the "if it doesn't say you can, then you can't" umbrella. So I will basically copy your setup as that seems to be the hot ticket. BMR, why U no have package with the TCA022?

Can't we run R-Comps in ESP, but in STX you have to stick with a streets? Will the 295s Rivals allow me to run STX/U?

Can we start this season!? ;-)

What Whiskey said. Go here and do some reading: http://www.scca.com/solo/content.cfm?cid=44517

 

[sheizasosay]

A shorter tire doesn't necessarily equal "less tire", does it?

No it definitely doesn't. My reply contained two parts: a "just in case you thought this" and a "what he likely meant by saying to use more AS with smaller tire".

Its possible someone could think that since lowering rear ride height via springs or coilovers affects the AS and having a shorter tire lowers your car, though in a different manner, that having a shorter tire affects your AS the same.

I wasn't implying you thought that, hence the "just in case".

 

[Whiskey11]

Whiskey,
What is the most recent weight on you car? As of now, my car has gained some *hitch and such*, but in full garb the car sat at 3200.

The last weigh in was when I had the car corner balanced over a year ago. All of my numbers are based upon keeping track from that number. My 09 GT premium as it sits weighs in at 3405lbs if my maths is correct, with an 1/8th tank of gas.

Things to remove weight from:
Battery -18
Seats -65 (I have the heated, powered, leather seats both driver/passenger)
Brakes -9
Exhaust -?? (Struggling to find LT's + Catted H pipe weights vs stock weights)

There are some other little nick nacky things that I could improve weight upon such as pimpy coilovers with aluminum bodies, lighter watts link setup, etc but those are beyond the weight of diminishing returns.

I'd be thrilled to get this car down into the 3300 range but we'll see when I get there if it's possible.

What have you done to get down to 3200? Which trim level did you start with?

I too am curious about this.

 

[Thinkkker]

I have an 06 premium w/shaker 500, so its a little lighter to start since its still an 06. In FS trim with about 3 gallons of fuel the car sat 3365.

Car had AST double adjustable fronts and single rears. Enkei 18x10.5 NtS03. Seats are NRG Carbon Fiber with Corbeau adjusters. C&L Cold air. That was when I got the weight to 3200.

I will have to reweigh the car to see where its at now. I have changed a few things on it.

 

[Arustik]

^^ Not surprised your weight is fairly low, these cars are lighter than people think.

My 05 Premium weighed in at 3429 (no driver) with 8 gallons of fuel just a few weeks ago.

Eibach R2 + bunch of suspension bits, Bassani axel-back, 1 Cobra Suzuka Pro, APEX 18x10s with 295 BFG Rivals, no rear seats.

 

[Boaisy]

Last time I weighed mine, about 2 years ago, it was almost 3600 even with me in it (when I weighed 180). I haven't weighed it since then, and I have put quite a few mods on.

 

[Vorshlag-Fair]

Looks like rally cars to ASP and out of ESP is a done deal...

http://scca.cdn.racersites.com/prod/assets/SEB 14-fastrack-Nov 1-3.pdf

#13113 AWD Cars Move to ASP
Delete the following listings in ESP:

• Eagle Talon Turbo (all) (1989-99)
• Mitsubishi Eclipse Turbo (1989-99)
• Subaru Impreza WRX (non-STI) (2002-07)

Add the following listing in ASP:

• Eagle and Mitubishi Eclipse Turbo and Talon Turbo (1989-99)
• Subaru Impreza WRX all incl. STI (2002-14), Legacy turbocharged (2004-2014), Forester XT (2004-2014)

With this set of changes, the recent allowance of aftermarket LCAs and Rear LCA relocation brackets (last month's FasTrack) to solid axle cars in ESP/STX/STU, and the Watts Link rule re-write finally taking effect in 2015 (fixing the errors in the ruling from 2013 that needlessly banned SOME brands of Watts Links over nonsense wording), things are looking up for the S197 in some Pony Car friendly classes.

 

[csamsh]

It's almost like Mustang people will be drawn back to real SCCA builds when the rules make sense...

Looks like rally cars to ASP and out of ESP is a done deal...

http://scca.cdn.racersites.com/prod/assets/SEB 14-fastrack-Nov 1-3.pdf

#13113 AWD Cars Move to ASP
Delete the following listings in ESP:

• Eagle Talon Turbo (all) (1989-99)
• Mitsubishi Eclipse Turbo (1989-99)
• Subaru Impreza WRX (non-STI) (2002-07)

Add the following listing in ASP:

• Eagle and Mitubishi Eclipse Turbo and Talon Turbo (1989-99)
• Subaru Impreza WRX all incl. STI (2002-14), Legacy turbocharged (2004-2014), Forester XT (2004-2014)

With this set of changes, the recent allowance of aftermarket LCAs and Rear LCA relocation brackets (last month's FasTrack) to solid axle cars in ESP/STX/STU, and the Watts Link rule re-write finally taking effect in 2015 (fixing the errors in the ruling from 2013 that needlessly banned SOME brands of Watts Links over nonsense wording), things are looking up for the S197 in some Pony Car friendly classes.

 

[Whiskey11]

It's almost like Mustang people will be drawn back to real SCCA builds when the rules make sense...

We still have to prove it makes sense and that these tweaks will increase population. The STAC wants to see increased participation in ST. I will be putting on 285's next season for STU and hitting at least Spring Nats and Nats.

Is there anyone else who is going to make the trip or am I going to be the only one... again? We need someone with actual driving skill to pilot a prepped car!

 

[csamsh]

Well I'm doing ESP with a co driver, who is thankfully faster than I and has previous nationals experience. I guess I was mostly referring to ESP with my comment.

STU....just wait for somebody to do a C5 build, or take their SSP C5 and put RS3's on it. Bye bye rest of competition. I briefly considered looking for a 2000 C5 coupe to do just this. I think the right driver could change the shocks, tires, put headers on it, and go win. I think it would at least give the 350z a run for its money.

Anyway...the point of all that...I think we're doomed in STU without more tire, or (ideally) some sort of tire allowance based on weight & power. The unscientific testing that Terry and I did last year was enough to make me not consider STU on 285's.

Now, from a non-competition point of view, I have more fun actually driving my car on the street tires. Unfortunately I think winning is more fun than driving.

 

[Boaisy]

I think with my current mods, I'm probably in SP now. I haven't looked at the SCCA rulebook recently to check.

 

[csamsh]

I think with my current mods, I'm probably in SP now. I haven't looked at the SCCA rulebook recently to check.

If you have the CF driveshaft listed in your sig pic you're all the way to SM.