Subiesport Magazine - April/May 2008 - (Page 94)

SUBIE TECH Advertiser Directory Audio Integrations 89 COBB Tuning 59 Cosworth 37 Disc Brakes Australia 51 Easy Street 8 Endura-Tech 19 Flatirons Tuning 46 H&R Special Springs 15 HarmanMotive 11 Hawk Performance Brakes 5 JSC Speed 53 Mach V Motorsports 13 MediaSpigot Photo Services 20 OAKOS Automotive 78 Performance Race Engineering 57 Subiesport.com 17 Primitive Enterprises 95 RacingBrake.com 91 Rally Armor 31 Royal Purple Cover 2 Slowboy Racing 58 Subaru North America Back Cover SubaruGenuineParts.com 67 Subiesport Subscriptions 79 Whiteline 55 This directory is provided as a service to our readers. To advertise your company in Subiesport Magazine, contact Ryan by phone at: 425-458-4949, ext 3. or email: ryan@subiesport.com Figure 4 - (top) As RPM increases, the total time to inject fuel decreases. (bottom) A stock turbo tuned STI with 560 cc stock injectors runs very high IDCs to maintain proper fuel-to-air ratios. A similar car with larger 740 cc Deatschwerks injectors runs much lower and therefore much safer IDCs. liseconds on a 4-stroke engine. At 6,000rpm this total available injection time is 20 milliseconds. Therefore, at low engine speeds and loads the IDCs are typically low. At higher rpm and load, IDCs rise. Low and high-impedance injectors explained. The coil is the driving force behind the open and closing of the injector. The more powerful, precise and consistent the coil, the better a fuel injector will be able to regulate fuel flow. There are two major differences in coil design that separate injectors into two main groups: low-impedance and high-impedance. Low-impedance coils have a lower electrical resistance and therefore require much more current when charging (opening) than does a comparable high-impedance injector. Low-impedance is great for quickly charging a coil and precisely controlling the opening and closing of an injector. However, the current needed to properly drive a low-impedance injector is not to be found in the stock Subaru ECU. In that regard, low-impedance injectors work very poorly unless the engine management is designed to run these higher-current devices. Because of this, stock Subaru ECU applications require the use of a higher-impedance injector for best tuning results. Higher-impedance injectors can be opened and closed using the lower current injector drivers of the stock engine control computer. Unfortunately, highimpedance coils are less capable of opening and closing larger injectors, and therefore the largest of injectors are generally low-impedance. Project STI gasses up! Our Project STI is gathering steam for what we hope will be a great season of drag racing and track events. During a recent dyno tune our beast hit the limits of the fuel system at 510 wheel horsepower on 92 octane pump fuel using 850cc injectors. Our lovely GT4037 hybrid turbo is barely breathing at this modest boost level of 24psi. The airflow should be 25 to 30 percent higher once we push the turbo into a better efficiency range of 30+ psi. The goal for this car is 600 to 650 wheel horsepower on race fuel. Clearly our power goals are writing checks that 94 MAY 2008

Table of Contents Feed for the Digital Edition of Subiesport Magazine - April/May 2008

Subiesport Magazine - April/May 2008 Contents Travis Geny Letters Readers' Rides Subaru News Wicked in White Pink Rules Harman Motive Nouveau Tuning the 2008 STI 2008 Rally Guide Alcan 5000 Rally Alcan Unleashed WRC Rally Monte Carlo WRC Rally Sweden WRC Rally Mexico 100 Acre Wood Kumakubo! D1 Drifting Where to Buy Subiesport 2008 Impreza WRX 2007 Legacy GT 1993 Impreza Wagon Fueled Up Ad Directory Spotted!

Subiesport Magazine - April/May 2008

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