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Do I need to run 93 octane or higher with the higher spark temp? I still have stock internals (no pistons, rods, or porting or intake manifold). so the only difrents is the spark. would running a mid grade help with responce?

Chris
 

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I don't think you have to, I always run 91 in my Focus but I have some stuff done to it.
 

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No. Amount of spark doesn't necessitate more octane; spark timing and compression do. Get new plugs and open the gap up to around .060-.065". The hotter spark is supposed to be able to jump a larger gap, giving more spark to more completely ignite the fuel/air mixture in the combustion chamber. I say .060"-.065" because they recommend .065", but some people say they get misfire with the gap that high - play around until you reach a happy medium.

To be completely honest, though - I've had the Screamin' Demon coil and Livewires combo for a couple of years now, and I don't think it really makes that big of a difference. The stock ignition coil is quite powerful and more than enough for even forced induction applications.

I always run 91 in my Focus but I have some stuff done to it.
Not to pick on you, but I don't see any mods in your sig that would mean you need to run 91. If that's all you have done, 91 is not only a waste of money, but it's building up carbon deposits on your valves and head.
 

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I like my Demon coil...not much of a difference in power though.
 

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I picked up about a MPG on my Focus, but not much of a seat-of-the-pants improvement in power. Run your car w/87 octane fuel. Unless you are running a power-adder or high-compression, the "higher grade" fuels will make no difference in your vehicle performance. Some actually claim that running premium fuel slows their car down since it burns slightly slower than the 87 octane regular. In fact, your owners manual instructs you to run only 87 octane.
 
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