Ford Focus Forum, Ford Focus ST Forum, Ford Focus RS Forum - View Single Post - anyone using premium gas ?
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Old 12-06-2011, 02:53 PM   #34
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Originally Posted by zak404 View Post
Running premium fuel allows the engine computer to advance the timing thus resulting in more power on the lower end torque curve, the burn time for higher octane fuel is also longer resulting in more power.
It would be interesting to see some dyno tests done with regular fuel and premium fuel.
Any of you that used to race will remember what quicker advance curves did for cars.
Adding advance does not necessarily mean more power. To get max power and efficiency maximum cylinder pressure needs to occur approximately 20 degrees after TDC. To much timing will hurt power just as much as too little.

Back when cars had distributors and springs/weights/vacuum controlled the advance curve the engineers didn't have the CAD tools to design and model engine designs that are available today. Quite often you couldn't establish the ideal advance curve because of poor combustion chamber design and inconsistent manufacturing so they established safe limits. This allowed the enthusiast to tune for their needs and make a significant improvement.

Today designs are very well optimized before the first piece of metal is machined and there is much less room for improvement.

A muscle car era bug block mopar needs upwards of 40 degrees of advance to make max power. The current generation Hemi, LS or Mod Motor makes max power with less than 30 degrees of advance and runs to much higher rpms.
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