| It's become apparent that the engine management on newer turbocharged vehicles are specifically designed to take advantage of higher-than-pump octane fuel when available. My wife's WRX runs SUBSTANTIALLY better with a splash of toluene than it does on just regular 92 octane. My largest complaint with the car has been it's surging/inconsistent throttle response as boost builds. When you pass about ~7psi at part throttle, you can tell the ECU is totally jacking around with the timing as it detects light knock. If you slowly lift off the throttle around 10-12psi, you will feel the engine lightly buck and surge. With about 1.5 gallons of Toluene in the tank, the throttle response is perfectly linear and smooth. Slowly lifting off the throttle around 10-12psi will be smooth and just as you would expect from any other car. Further research into the design of the engine management setup reveals some very clever knock control systems that can widely and granularly alter the engine's octane requirements. Much like the "low octane" z32 maps, the WRX apparently has 10 "performance levels" that will scale timing and fuel delivery based on what it learns of the fuel octane by constantly "testing" the limits. (advancing timing until knock occurs, then backing off slightly) It seems to scale from ~89 to ~94 octane. You can get piggyback setups like the UTEC and manually adjust the knock threshold, timing correction, and duration. Apparently the new US-Market Lancer EVO has a similar setup that scales to ~100octane, although specific details about it are still very sketchy.
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