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Old 08-01-2014, 03:34 PM   #1
Speed Addict
Scooby Newbie
 
Member#: 327313
Join Date: Jul 2012
Chapter/Region: International
Location: Brasil
Vehicle:
2009 WRX STI
68 Alfa 1750 GTV

Subaru Banner Slow Spool up + Narrow Power Band : 473whp STI w/ CS600 Cosworth Longblock

I have a 09 STI with a Cosworth CS600 Longblock with the supporting parts/mods that are listed after the text below.

For now, hp is satisfactory as the car has been Dyno'd recently with 473 awhp @ little under 7k rpm with 1.7kg (+-24 psi) turbo boost. The issue is that I have slow spool up for a GTX 3076R turbo and when the wastegate does open it snaps to 80's-F1-style all or nothing binary power delivery.

I've had many turbo cars including a much missed GC8 2000 Impreza but none of them were even close to this kind of all or nothing narrow power band.

Don't get me wrong, I'm very happy the car is awesome and a riot do drive, but, I do track days and the first and only TD I took this particular car I was losing traction on all fours when the boost kicked in around 4650 / 4800 rpm on Pirelli Stock Car Slicks, in second gear. This cost me dearly on my lap times and to make matters worse, I hit the stock rev limit all the time and the rpm drops below the narrow power band on every gear change.

My tuner and I have a few ideas of what would improve spool-up time in theory, but, before I spend more of my hard earned money on parts I would really appreciate some input from anyone that feels they can contribute on what would be their course of action.

I can post the dyno chart if anyone thinks it will be usefull.

Thanks in advance!

Parts List:
Cosworth CS600 longblock - 2.5L 8.21 CR Forged Crank, big valve headers w/ high lift cams + titanium springs and retainers
Custom G&R Reinforced deck treatment
Garret GTX 3076R Externally Gated Turbo (standard location)
Tial MVR Wastegate
Tial outlet pipe for ATP GT30
Perrin FMIC
Perrin Turbo 3" Inlet Hose
Samco Radiator Hose Kit
K&N Cone Filter
DW 265 Series Fuel Pump
DW 1000cc topfeed injectors
Cosworth High Flow Fuel Rails
Cosworth TGV
Cosworth Heavy Duty Timing Belt
Aeromotive Fuel Regulator
Tomei Fuel gauge
Tomei Fuel Rail Adaptor
Killer B Performance Large Oil Pan
Killer B Oil Pickup
Killer B Oil Baffle
Grimmspeed Boost Control Solenoid
Braided AN Steel Air Lines
Braided AN Steel Fuel Lines
Braided AN Steel Brake Lines
Perrin Master Cylinder Brace
DBA 4000T3 Slotted Front Rotors
Ferodo DS3000 Pads
Invidia Catless Downpipe
Invidia Up Pipe
Invidia Q300 Cat Back Exhaust Titanium Tip
Grimmspeed Exhaust Manifold Cross Pipe
Custom G&R front air ducts for rotors
Exedy Twin Disc Clutch
Kartboy/Turn In Concepts Short Shifter and all Bushings
Eibach Prokit Lowering Springs
Eibach Rear Swaybar
Whiteline Rear Camber Bushings
Whiteline Camber Bolts Front
Whiteline Antilift Kit
Whiteline Subframe Rear Traction Kit
Whiteline Steering Rack Bushings
Defi Red Racer EGT Gauge
Defi Red Racer Pressure Gauge
Defi Red Racer Boost Gauge
PLX Air Fuel Ratio Sensor Module and Single Gauge Combo
Perrin Gauge Pod adapters
Perrin Dual Gauge Pod

Parts that will be bought before more track duty:
Mishimoto Oil Cooler Kit
Mishimoto performance Radiator
KW V3 coilovers
Cusco Top hat
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Last edited by Speed Addict; 08-02-2014 at 02:40 PM.
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