SoloRu Modifications

posted by neilschelly on Mon, 2008-10-13 07:44
neilschelly's picture

Interior Modifications:

  • Custom-made UltraShield RallySport seats
  • Cam-Lock UltraShield 6-point harnesses
  • NRG suede steering wheel and NRG QuickRelease 2.0
  • G-Tech Pro/SS in-car performance computer
  • AutoPower Race bolt-in 4-point roll bar
  • Vacuum, oil pressure, oil temperature gauges

Suspension:

  • Race Comp Engineering Tarmac-2 coilovers, 600/500 pound F/R springs, with tender springs, Vorshlag camber plates, and Torrington bearings at all 4 corners.
  • Camber bolts at each wheel
  • Rear strut tower bar
  • Tribeca 25mm front sway bar
  • Whiteline 22mm adjustable rear sway bar, on stiffest setting
  • Modified Kartboy rear endlinks
  • Custom-made heim joint front endlinks by Small Fortune Racing
  • Hoosier A6 autocross tires in 255/40R13, mounted on 13"x9" Diamond Racing wheels
  • Falken Azenis RT-615K tires in 195/60R14 street tires, mounted on 14"x5.5" steel wheels
  • ARP extended lug studs on all 4 corners

Bushings and Mounts:

  • SuperPro Steering rack bushings
  • STi GroupN Engine Mounts
  • STi GroupN Transmission Mount
  • Reinforced Pitch Stopper: This started as a JDM STi pitch stopper and was further reinforced with polyurethane by Deyeme Racing
  • Kartboy front/rear shifter bushings
  • Kartboy transmission crossmember bushings
  • Kartboy rear differential crossmember bushings (race durometer)
  • Reinforced rear differential subframe bushing (Windo-Weld)

Suspension Work:

  • -3.5 degrees of rear camber, -4 degrees of front camber, and 1/8" front and rear toe out.
  • Corner balancing by Small Fortune Racing

Drivetrain Equipment:

  • Subaru XT clutch-based rear limited slip differential
  • Exedy organic clutch
  • ACT Street Lite flywheel
  • Phase 1 5MT transmission from an EJ18 Impreza (with approximately the RS gearing)
  • OBX Helical front differential
  • 5MT DCCD (electronic center differential) from a Version 1 JDM STi Type RA
  • DCCDPro Universal Controller.

Engine Modifications:
During the winter offseason from 2007-2008, I built an EJ22 motor (from a 2000 Outback Sport) to the best Street-Prepared motor I could muster. The only rules I didn't take full advantage of were balancing the crank (which I've heard varying opinions on it being useless or nearly useless for Subaru boxer motors and the max allowed 0.047" overbore. The 0.020" overbore I did could be accomodated by pistons and rings from Subaru for really cheap, whereas the full allowed overbore would have required I commission custom-made pistons.

  • Porting the intake manifold: I'll worked with Small Fortune Racing to get better flow out of the stock intake manifold. It looks decent to begin with and seems to have a good flow already, but cleaning out the casting leftovers and porting and gasket-matching seems to have improved it. Results here and here.
  • Phenolic Spacers from Grimmspeed, to increase intake plenum volume and reduce intake manifold temperatures.
  • Smoothing the throttle body: There's a small seam in the throttle body that probably negatively disrupts airflow through the throttle body. Small Fortune Racing worked on this with the intake manifold. Results here.
  • Reshaping the heads' ports: The intake ports and exhaust ports both have a lot of excess material available to widen the ports and increase head flow. Small Fortune Racing worked on this with the rest of the intake. Intake port results here and here. Exhaust results here.
  • Planed the heads: The heads were planed 0.012" as specified in the service manual for a little extra compression.
  • Bore out the cylinders: The cylinders can be bored out up to just over 0.040" diameter according to the rules, assuming you can find new stock-weight/shape pistons to fit. I used the Subaru 0.020" second standard overbore pistons (they don't make bigger) and had the machining/boring done at Performance Automotive Technology.
  • Intake: The intake is a high-temp flexible rubber hose paired with a nice K&N cone filter in the fender well for lots of forced cold air.
  • Exhaust: A set of aftermarket equal-length exhaust headers for the single-port engines doesn't exist. I got a high-flow cat from Random Tech and had a local shop connect that up to a FlowMaster Series 40 muffler with 2.25" piping and two Vibrant Technology 12" resonators. Headers will have to wait and I'm not sure I need them anymore, as power definitely felt better when I added the resonators.
  • Lightweight and Underdriven pulleys: I've got a power steering pulley (from Group A), alternator pulley (from Unorthodox Racing), and an underdriven crank pulley (from Unorthodox Racing).

Brake Modifications:

  • 240mm front disc brakes from early FWD Imprezas (to fit under 13" wheels)
  • 260mm rear disc brakes (using '98 RS calipers ground to fit within 13" wheels)
  • Goodridge stainless steel brake lines
  • ATE Super Blue or Typ200 brake fluid
  • Single-stage brake booster
  • Hawk HPS pads in front
  • Porterfield R4-S pads in rear
  • Brake vacuum reservoir: This will come in handy since I've been frustrated more than a few times by having my power brakes cut out on me after lots of left-foot-braking without releasing the gas pedal, like in extended slaloms.
  • Lachute Performance Master Cylinder Brace

Other Modifications:

  • Removed Air Conditioner (~30lbs, 25 of which in front of the front axles)
  • Odyssey PC680 lightweight battery, relocated to rear of the car (35lbs in front of the front axle moved to 15lbs in back)
  • Removed roof rack (10lbs from roof))
  • Removed Fog Lights (5lbs from front bumper)
  • Removed stereo and amplifier (30lbs)
  • Swapped for a plain 'L' hood (5lbs from over the front axle)