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Old 11-07-2014, 05:59 PM   #1
Ben_
 
Drives: 2010 Yaris Hatch
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Imaginary STF build

Hey guys,

I don't have money to spend on lots of expensive parts plus next season for Utah region SCCA doesn't begin till next March, but I still love writing up potential builds. Here is one for the STF class, which has a pax of 0.801 compared to the HS pax of 0.797. Not a huge difference for the MUCH greater possibility to maximize the performance of our little cars! This build has parts with bang for buck and performance in mind.

So beginning from the ground up, since that is the best way to build a car for auto-x IMO.

http://www.tirerack.com/tires/tires....R5GFR&i1_Qty=4

225-45-15 BFG Rivals maximizing the tire width limit of STF, maximizing the UTQG limit of 200 for 2015, and keeping a small diameter for gearing benefits

http://www.tirerack.com/wheels/Wheel...&association=2

Advanti Storm S1 15x7 e35 which is the exact width to match the tires also is within width limits of STF and is more budget oriented than Enkei RPF1 but is only 1 pound heavier per rim

All of the following are available on Micro Image

R1 concepts drilled and slotted rotors with carbotech track pads, SS brake lines and custom venting from the fog light holes or lower bumper grill rear brakes must remain drums to keep the factory parking brake

Whiteline 23mm rear antiroll bar, Megan Coilovers

micro image intake manifold, 1.8L TB, AFE 1.8L intake, remove plastic engine cover

Megan Header, custom 2.25" straight pipe with high flow cat

APEXI AFC-neo piggyback tuner

DENSO spark plugs, MI lightweight crank pulley, K&N oil filter

Micro Image shifter cage bushings, MI shifter cable bushings, MI short shift kit


Total Cost = 4586.94 + shipping + tuning + exhaust fab
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Old 11-07-2014, 06:27 PM   #2
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you can't change your manifold out on in STF class. that will put you in FSP

You can't do piggy back unless it is a plug'n play. No splicing wires allowed

You also can't run piping for brake cooling either. Has to remain oem.

I would go with Hankook RS-3 in 225/45/15 personally. Rivals are good also, but the RS-3's like cold weather a bit more and are more forgiving than the Rivals. Rivals don't talk back, when you break that grip, its over. RS-3 are more forgiving and like more tire pressure.
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Old 11-07-2014, 07:55 PM   #3
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Everything else you got is pretty standard in stf. Only thing i would suggest is alignment. Get some crash bolts for the front to get more camber. I would not mess with rear alignment shims. Play with tire pressure first.
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Old 11-08-2014, 07:45 PM   #4
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Intake manifold can be swapped in stf. Anything leading up to the block is fair game. Obviously I don't understand how the apex fc works. Is there a fc that is stf legal?

There was some talk going around about the hankooks this season. One of our regions best drivers got a set for his focus st in stock class and did not like them. I don't remember his comments in specific but he liked his previous set of tires better. I'm not sure what they were. Anyways the rivals are the most popular tire in our club and there are a lot of great drivers who swear by them. Maybe its because all of the venues we use have 'coated' or 'sealed' asphalt and gives minimal grip compared to concrete or plain asphalt.

My personal experience is with OEM bridgestone potenzas, khumo all seasons, and 1 weekend on concrete (my only cross on concrete) with a set of proxies r1r I got used from another Utah region guy with not much life left. The proxies had greatly improved steering feel and I'm not too sure about grip, but I'm sure it was a great improvement.
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Old 11-08-2014, 11:41 PM   #5
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Not sure what the seat rules are in STF, but in HS I run a 3" lap-belt for safety reasons. By strange coincidence, it works well to hold your butt in the seat so you can concentrate on driving. If you have an expired harness around, might be worth doing..... for safety ;)

I'd say camber, and whatever you can do to make use of as much of the front tires as possible (instead of the usual outside 1/3) will be the first priorities. Saves you money on tires in the long run too.
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Old 11-08-2014, 11:44 PM   #6
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Rule book states in 14.10.C
Air intake systems up to, but not including, the engine inlet may be modified or replaced. The inlet is the carburetor, compressor inlet, throttle body, or intake manifold, whichever comes first

There fore the throttle body cannot be changed, but cai is allowed.
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Old 11-08-2014, 11:48 PM   #7
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Anything allowed in HS is allowed in ST. So harness belts are allowed. Racing seats are also allowed, but have to weigh at least 25 lbs. including brackets and rails.
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Old 11-08-2014, 11:53 PM   #8
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http://www.scca.com/solo/content.cfm?cid=51804

If you check out the scca site and look at the archives, hankook is the dominating tire that 1st place drivers are running.

This year i ran toyo up front and hankook in back. Decent setup, but i miss my hankooks.

I placed 2nd this year in my region running stf.
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Old 11-09-2014, 12:00 AM   #9
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As far as piggybacks. You can make your harness or see if someone can do it for you. Its alot of work. Boomslangs run about $500.
I dont think its really worth it because you cant change timing with it and the toyota ecu does a great job on its own calculating a/f to compensate for the increase of air flow cai adds
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Old 11-09-2014, 08:29 PM   #10
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I was looking at the rules for street prepared, haha. Good eye.

Without the cost of the manifold and the fc the total cost would be much lower at around 3450. A very reasonable chunk of change but I'm sure this is worth at least a few seconds on lap times. Are the mods you have similar to this list? How much of a time improvement do you think this is worth? How much HP increase do you think the mods are worth?

As far as the seatbelt goes I usually lean my seat back and pull the seatbelt hard to lock it and use that to keep my butt in the seat. Works much better than nothing but I'm sure a good seat and 5 point harness would go a long way towards decreasing lap times. I often catch myself using my left leg to brace myself in the seat. No good :(
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Old 11-09-2014, 08:31 PM   #11
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no need for a 5 point or harness bar, risk of submarining is very low with autocross.
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Old 11-09-2014, 08:38 PM   #12
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It is cool seeing some yaris taking trophies in stf. :D
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Old 11-09-2014, 10:24 PM   #13
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I have a sparco fixed racing seat. I agree with xnamerx with the harness and bar. It looks cool to have, but not necessary if you got a good seat. I was using a lap belt for my first year in the yaris. Basically a seat belt that wraps around your waist and around the back of the seat. I was getting annoyed by the same problem you are having. I still braced myself with my leg against the door and the center console, even my left arm against the door on some occasions. Now I have a good seat that fixed my butt in place, but I still use my oem seat belt.

Yes, your setup is very similar to mine.
My engine
AEM CAI
Megan Headers
High Flow Cat/custom midpipe
Tunabe axleback
NST light weight crank pulley
Ballistic Ultra lightweight battery (2.8 lbs)

Suspension
Megan coilovers
23mm UR rear swaybar
Front TRD Camber bolts (2.8 neg camber in the front)

Interior
Sparco Racing seat

Grip
Rota GT3 rims 15x7 ET40
Hankook RS3 225/45 (psi: front 40ish rear 55ish)

Brakes
Currently OEM
I do plan on getting stainless steel lines and Hawk pads eventually for more bit, but I am doing good with what is on the car currently.
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Old 11-09-2014, 11:24 PM   #14
CoryM
 
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re: harnesses, it's my understanding that only lap belts are allowed.
"non-factory upper body restraints may only be used in open cars,
cars with targa-tops in the open position, or cars with T-tops in the open
position"

I just use the same lap belt holes as the OE and it works fine ( I use both belts on course). Just yank it tight before each run. You also don't really want tight upper harnesses without a HANS or similar. Basal neck fractures and all that.
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Old 11-10-2014, 05:31 AM   #15
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I don't know where you found that. What chapter, section did you get that from? That may be true for Street class, but I do believe Street Touring is allowed to have a harness bar and a harness
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Old 11-10-2014, 05:39 AM   #16
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Harness bars are allowed for a harness also in street class, therefore, its allowed in all classes
13.2
H. Driver restraints as outlined in Section 3.3.1 are allowed. Seats may
not be cut to allow for the installation of alternate seat belts or harnesses.
Passive restraint systems may disabled but may not be removed.
Removeable seat headrests may be repositioned using the
original mounting hardware only if the OE components permit it with
no modifications. This includes removing a headrest and reinstalling
it backwards. A horizontal “harness bar” may be used as part of the
installation hardware for allowed driver restraints provided it has no
more than 2 attachment points to the chassis and is bolted at those
locations. A C-type harness bar may also be used. It may have 4
bolted attachment points to the chassis (2 primary and 2 supporting
connections to resist rotation). Truss-type harness bars are not allowed.


And in street touring section 14.1
AUTHORIZED MODIFICATIONS
All SoloŽ Rules Street Category allowances, plus all allowances contained
here in Section 14
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Old 11-10-2014, 02:54 PM   #17
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The part I posted is 3.3.1, which your part references. I asked on my local club and the reply I got was to run the lap belt AND the OE 3-pt. Which makes sense with airbags.

Cheers.
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Old 11-11-2014, 09:42 AM   #18
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Yea, you gotta kinda read that as a whole instead of picking parts out of it.

Seat lap belts are required in all cars, and must be installed in cars with
passive restraint systems that do not include a lap belt
. Installation and
the use of shoulder belts or harnesses is strongly recommended, however
non-factory upper body restraints may only be used in open cars,
cars with targa-tops in the open position, or cars with T-tops in the open
position when two conditions are met:
A. The roll structure must meet either the requirements of Appendix C
or the Club Racing General Competition Rules (GCR) 9.4.
B. The top of the roll structure may not be below the top of the driver’s
helmet when the driver is in the normal driving position.

The whole lap belt required is that back in the day, they didn't have seat belts. So a stock car wouldn't have them. Then they came out with cars that had the mechanical shoulder belt that would choke you when you closed the door (80s accords). The lap belt was a separate buckle from the should buckle and could easily not be buckled in.

The part that is says:
however
non-factory upper body restraints may only be used in open cars,
cars with targa-tops in the open position, or cars with T-tops in the open
position when two conditions are met


This saying that, aftermarket harness can only be used in open cars when 2 conditions are met which is A and B.

In other words, you can not use aftermarket harness in an open car if you do not meet these 2 requirements:
A. The roll structure must meet either the requirements of Appendix C
or the Club Racing General Competition Rules (GCR) 9.4.
B. The top of the roll structure may not be below the top of the driver’s
helmet when the driver is in the normal driving position.
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