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I have a '94 mustang GT convertible. it is stock except for shorty headers. I currently use 87 octane gas, the cheap stuff. I've heard I should use 93 octane. Can my car use that gas, and why should I use it ? Oh, I plan on getting a performance chip soon, would that change what gas type I should use ?
 

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If your engine is stock and you are using the stock ECU tune, then there is no reason to use anything more than 87 octane, your car won't make any more or be any faster. If you get a chip though, chances are you'll have to use premium fuel, since the chip will change the ECU parameters and bump up the timing to eek out a little more power.
 

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Don't fall for the the common delusion that higher octane means higher performance. That's backwards. It's higher performance engines that need higher octane.

Higher octane just means the fuel can tolerate a higher compression ratio without detonation ("knock") a condition where the fuel/air mixture starts to burn before the spark fires, from the heat caused by compression (like a diesel).

Unless you raise the compression ratio of your engine, it needs no higher than 91 octane to get full performance. If the owners' manual says 87 octane, that's plenty, but most cars now need at least 89. Any higher octane would be treating a problem you don't have, like giving antibiotics to someone who has no bacterial infection.

A high performance chip may alter the ignition timing and fuel mixture. If it advances the spark, then a higher octane gas may be in order. If it richens the fuel mixture, then that won't change the octane requirement. The chip manufacturer will tell you what octane gas to use.
 

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it realy dosnt matter you can boost the octaine on the 87 when ever you want with overthe counter octain booster or fuel injecter cleaner,the gas will not efeect the chip, if you wanna make big power go for a super charger and shorty headers
 

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Definitely NOT 93, Octane ratings are based on compression ratios and your headers or chips will not affect the ratio but might need to adjusted after the chip is installed.
 

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timing changes can affect ping, no a higher octane would be needed, but if you are running perfectly on 87, then use 87, theirs literally NO gain to using higher octane fuel if you don't need it
 

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uhhh. read the manual. it will tell u what to use. i use 93 octane in mine gt mustang and it runs a lot better!!!
 
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