The CS/STX Debate

dhiraj_stxAh yes, the SCCA. Riddled among the detailed rule book, countless pages of conduct guides, classing designation, number width requirements and placement of it on the car, details the issue of port installed options for Street Classing aka Stock classing. In short this means as long as the manufacturer allows an accessory to be installed at the port harbor is legal. One could simply see the guys at the TRD Marketing department almost rub their hands together and queue some evil mastermind music. The powers to be at TRD then published a revised version of the accessory catalogue where the TRD lowering springs and beefier sway bars (essentially a rebadged Eibach kit) were labeled as port installed options for the FRS. After all, why wouldn’t you be able to charge 1.5 times the cost of the MSRP and label it as a genuine TRD product. That’s just good business…

The BRZ however, did not get the option. Letter writing campaigns did not make a difference here, so the BRZ’s were left without the cool kid toys and a lot of BRZ owners to questions whether to stay in the CS make the move to STX.  Would it make sense to drop the $3500 on the FRSport Bilstein MDS kit?

The issue lay in the fact that even if you drop the coin on this awesome double adjustable kit, you’d still be up against the FRS’s of the CS-World. Due to the port installed rule, the FRS’s would be able to utilize these shocks and the TRD lowering spring/sway bars giving them a significant advantage.   It was time to really sit down and make a conscious decision.

The Thought Process

After some deliberation, the decision was made to use the money towards building a STX Setup. While in the long run this yields to a more money spent, every single shortcoming of the car could be addressed. For the everyday Grassroots Racer, making the dollar go as far as it can is something we all face. This build details the apexjunky approach of how to build a competitive Twin in the SCCA’s hot STX Autocross Class while being as gingerly on the wallet as possible. The mission is simple: Save money where you can, but don’t cheap out on the crucial parts.

The apexjunky Pilot

Dhiraj Jadhav is an upcoming driver in the San Diego Region. Starting out in C-Street with his 2013 BRZ Limited, he’s driven the car in a few configurations and was ready to make the move to STX after the debate was settled. His cheery disposition, attention to detail due to his engineering background, made the move from CS to STX fairly obvious.

The Vehicle

The car that we will be working with is a 2013 Subaru BRZ Limited.

The Build Ideology

Due to the sheer nature of the modifications allowed in STX and the fact we needed to work with on a budget, we had to approach this in a systematic way and in phases.  Being hands on Dhiraj wanted to focus on building the car himself as much as he could. Even with little to mechanical experience, the FRS/BRZ platform is a remarkable car to work on with everything fairly accessible.  We felt confident in proceeding with the install.

Phase I – Suspension & Wheels

Dhiarj’s car was already somewhat set up for C-Street with a Perrin front Bar and TRD exhaust…what we then focused on was the suspension.

This is by far the most critical part of the build. After some options which included the Ohlins DFV, and the KW Variant 3, which could be sourced from HG Motorsports, we settled on a Bilstein PSS10 Coilover Kit.

Here is the parts list of the items utilized Phase I:

  • Bilstein PSS10 Single Adjustable Coilover Kit 
    • The reason for this choice over the other ones was because Bilstein is local (Headquartered here in Poway, CA), and we have Bret Norgaard, ex-Bilstein R&D Engineer, and owner of YAWSPORT to reach out to for rebuilds, tuning expertise and revalves. His vast experience in this area along with Bilstein’s rich motorsport history made this a solid choice for us.
  • Raceseng CasCam Plates with PSS10 Spring Perch 
    • The only unit that allowed for adjustment of camber and caster (still in production) was  the Raceseng CamCas Plate. Having seen this plate in person, it was a clear winner for it’s machining and durability.
  • Cusco USA Adjustable Lower Control Arms
    • Street Touring rules dictate either the toe or the control arms can be modified with adjustable units. We went CUSCO it’s durable construction of control arm and amazing Grassroots support.
  • 17×8 +35 Enkei RPF1
    • The 8″ wheel would a good way start testing and tuning tire choice. It was also the easiest to find a set of used wheels on the market for a a reasonable price. Currently mounted on are 225/45/17 Bridgestone RE71R (as of 12/10/15), which will get us to figure out the car’s behavior.
  • Winmax W3 Brake Pads
    • After running the Winmax Pads on the WRX, we found it very difficult to match the braking feel to any other brand. Our WRX felt as though it was fitted with a big brake kit with a simple pad swap and as such we recommended Dhiraj go with these. The low curb weight of the BRZ would allow the W3 compound pad to properly stop the car aggressively enough to yield a huge braking advantage.

(Phase I is completed as of 12/10/15 with the Winmax pads on order next month).

Phase II – Power

Delicious Tuning in San Diego has a fantastic STX tune which allows to get close to 200WHP on 91 octane (more if you utilize higher octane fuel). What we intend to utilize is the following:

  • Tomei Equal Length Header
    • Dyno results prove that the EL header produces a better power curve, but we will reach out to Delicious to ensure that this is the case.
  • Delicious Tuning Tune With Launch Control
    • Local to San Diego (well Escondido to be precise), and fantastic community support.
  • Revisit Exhaust options for potential lighter weight muffler

Phase III – Differential and Seats

We’ll be utilizing the Cusco lineup of Differentials and most likely the Bride seats. More on this later.