Octane Question
11-15-2006, 08:53 AM
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Octane Question This isn't totally related to LS1's but just a Gas/Octane general question. I was discussing octane and gas with someone who has a new car which is designed to run on regular. Here is his theory:
"Premium fuel in a car designed for unleaded will give you benefits as its a cleaner fuel, leaves less deposits, better performance/economy (higher octane rating)"
Now I thought that cars the require regular unleaded burn different and technically using premium would actually leave deposits because it's not being "burnt" properly. Am I crazy or is he right
"Premium fuel in a car designed for unleaded will give you benefits as its a cleaner fuel, leaves less deposits, better performance/economy (higher octane rating)"
Now I thought that cars the require regular unleaded burn different and technically using premium would actually leave deposits because it's not being "burnt" properly. Am I crazy or is he right
11-15-2006, 09:11 AM
#2
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Fuel in the US is a little odd as you have a cheap fuel 87 octane.
Now octane rating stands for the combustability of the fuel. High octane fuels don't combust as easy and thus allow higher states of tune of boost with less risk of detonation.
You won't automatically pick up HP using higher octane fuel. Some cars do, mostly turbo's but they need the electronics such as anti knock to be able to do this.
The new s197 Mustang is rated to run 87 octane. Running 91 or 93 won't really give you any HP unless you get the PCM tuned for it. But it won't do any harm either.
Now this is where it's a little odd, as I think the 87 octane fuel has slightly different content and generally is cheap by comparison. Not sure of the exact content but I think premium has a form of cleaner in it which is good for the engine/injectors.
Don't run 87 in a car tuned for higher octane though, this will pull timing as a best case and reduce power but it may cause detonation and just run like crap and cause damage.
Now octane rating stands for the combustability of the fuel. High octane fuels don't combust as easy and thus allow higher states of tune of boost with less risk of detonation.
You won't automatically pick up HP using higher octane fuel. Some cars do, mostly turbo's but they need the electronics such as anti knock to be able to do this.
The new s197 Mustang is rated to run 87 octane. Running 91 or 93 won't really give you any HP unless you get the PCM tuned for it. But it won't do any harm either.
Now this is where it's a little odd, as I think the 87 octane fuel has slightly different content and generally is cheap by comparison. Not sure of the exact content but I think premium has a form of cleaner in it which is good for the engine/injectors.
Don't run 87 in a car tuned for higher octane though, this will pull timing as a best case and reduce power but it may cause detonation and just run like crap and cause damage.
11-15-2006, 09:39 AM
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See I always thought that if a car is tuned to run on 87, that if you were to run a higher octane that the car wouldn't make use of that extra octane, thus no real benefits other than a cleaner fuel.
11-15-2006, 09:51 AM
#4
300bhp pretty much nailed it. Octane rating is nothing more than a fuel's resistance to combustion. 93 doesn't combust as easily as 87, so you can run more aggressive spark curves/compression ratios/boost levels as you move up in octane rating. If the car is tuned to run on 87, the only way you'll pick up power with higher octane fuel is if you are experiencing spark knock (pinging) with the lower octane (resulting in the pcm pulling timing). As far as higher octane being cleaner, I say phooey. Nothing about 87 octane will be "dirtier" than 91/93 once past the fuel filter. JM2C. 
