Subaru Enthusiasts Car Club of the Sierras - View Single Post

cody · 2009-03-26, 12:27 PM

Only if you'd knock without it. A proper 91 octane tune won't knock under normal circumstances, but even a good tune will knock on a hot day with a heat soaked IC. This is where you'll see the benefit of NOT LOSING performance due to the heatsoak>knock>ECU retarding timing. 100 octane actually has less energy per liter or whatever than 91 octane, but since it does it's job and decreases the propensity for the car to knock, you can run more advanced timing and boost on it. That's how race gas tunes will take advantage of it. I spike my octane with Torco when I autoX on hot days even though I'm tuned for 91.

2009-03-26, 12:27 PM	#27
cody Candy Mountain Real Name: Cody Join Date: May 2005 Location: Californication Posts: 7,751 Car: 03 Pussy Wagon, now with more pink! Class: TESP OMG Internet!	Only if you'd knock without it. A proper 91 octane tune won't knock under normal circumstances, but even a good tune will knock on a hot day with a heat soaked IC. This is where you'll see the benefit of NOT LOSING performance due to the heatsoak>knock>ECU retarding timing. 100 octane actually has less energy per liter or whatever than 91 octane, but since it does it's job and decreases the propensity for the car to knock, you can run more advanced timing and boost on it. That's how race gas tunes will take advantage of it. I spike my octane with Torco when I autoX on hot days even though I'm tuned for 91. __________________ Slow and low, that is the tempo.