Gas Octane questions
Thread Starter
Staging Lane
Joined: Aug 2005
Posts: 80
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Gas Octane questions Hail,
I was arguing with an co worker of mine regarding 91, 89, 87 octane. He ask me why do I need to put 91 octane on your Camaro. His questions was that " is 91 octane a necissity for your vehicle and this guy uses 87 on his 2007 lexus. What's your guys thought on this?
I was arguing with an co worker of mine regarding 91, 89, 87 octane. He ask me why do I need to put 91 octane on your Camaro. His questions was that " is 91 octane a necissity for your vehicle and this guy uses 87 on his 2007 lexus. What's your guys thought on this?
Yes you need to run 91 octane in your car because it was tuned from the factory to run on 91. If you put lower octane gas in it will absolutely run, but the computer will pull timing to avoid detonation which will reduce power output. Plenty of info on this board about octane and what it is/does, do some searches and you'll have lots of ammunition to back up your argument with your coworker.
Teching In
Joined: Oct 2007
Posts: 14
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From: east side st paul for life
yes and no i dont know about how they come tuned but i tuned mine with a hypertec to run on 87 this will decrease my power a bit but i think i have enough and gas costs enough $$$. if you run 87 when its tuned to 91 it will create a pinging sound beacuse the gas isent igniteing on time. this is very hard on your. car if you ever start to hear these run it on 91 right away
The reason LS1/LT1 engines call for premium fuel is because of the high compression ratio, which makes them more likely to knock. The higher octane fuel has higher knock resistence. And as was said before, these engines CAN run on 87 octane, but this will result in reduced power.
Even if you pull timing you won't make good power on low test. It is all about compression ratio.
Another misconception is people with **** cars think putting high test will magically transform their car. Waste of money.
Another misconception is people with **** cars think putting high test will magically transform their car. Waste of money.
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12 Second Club
Joined: Sep 2005
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From: Bucks County, Pa.
Hail,
I was arguing with an co worker of mine regarding 91, 89, 87 octane. He ask me why do I need to put 91 octane on your Camaro. His questions was that " is 91 octane a necissity for your vehicle and this guy uses 87 on his 2007 lexus. What's your guys thought on this?
I was arguing with an co worker of mine regarding 91, 89, 87 octane. He ask me why do I need to put 91 octane on your Camaro. His questions was that " is 91 octane a necissity for your vehicle and this guy uses 87 on his 2007 lexus. What's your guys thought on this?
F*** the yuppiedrone, use 91 and then show him why by blasting his TOYota's doors off!! 
Gas companies are largely to blame for that, they make people think that premium is somehow "better" than regular through marketing, and you just cannot tell some people otherwise. Most people don't know anything about cars.
What most people don't understand about octane is that the higher the rating the better it's ability to resist pre-ignition. It doesn't give you more power just because it's 93 vs 87.
Diesel engines operate by heat of compression. As the piston moves upward on the compression stroke the temperature in the combustion chamber rises. It's this rise in temperature alone that ignites the fuel and air mixture, because there is no spark plug to ignite it.
In gasoline engines we do NOT want this to happen. We need the fuel to be stable enough to withstand the heat and the amount it's being compressed so we have as much of the fuel there to ignite when the spark plug fires.
To put it simply if your engine is running fine with no pinging or knock-retard on 87, then you will see no gains or benefit from running 93. If you have an engine like an LS1, or other engine with higher compression and more aggressive timing tables, you will need to run higher octane.
Now here is where a lot of people get lost...the most power is made using the lowest octane without seeing pre-ignition. Use higher than you need, and you could actually lose power. I get funny looks from old school guys all the time when I tell them my 11.34-1 SCR heads/cam car runs perfect on 93, and that I have NEVER ran "racing" fuel in it.
Diesel engines operate by heat of compression. As the piston moves upward on the compression stroke the temperature in the combustion chamber rises. It's this rise in temperature alone that ignites the fuel and air mixture, because there is no spark plug to ignite it.
In gasoline engines we do NOT want this to happen. We need the fuel to be stable enough to withstand the heat and the amount it's being compressed so we have as much of the fuel there to ignite when the spark plug fires.
To put it simply if your engine is running fine with no pinging or knock-retard on 87, then you will see no gains or benefit from running 93. If you have an engine like an LS1, or other engine with higher compression and more aggressive timing tables, you will need to run higher octane.
Now here is where a lot of people get lost...the most power is made using the lowest octane without seeing pre-ignition. Use higher than you need, and you could actually lose power. I get funny looks from old school guys all the time when I tell them my 11.34-1 SCR heads/cam car runs perfect on 93, and that I have NEVER ran "racing" fuel in it.
The only thing I can think of is that with cheaper gas there might be buffers that they use to cheapen it up. Like methanol or some other chemical. [Would that be cheaper though?] That would be the only way you might be less MPG from low test. But that means there are variables in this. Not comparing the same thing...
What most people don't understand about octane is that the higher the rating the better it's ability to resist pre-ignition. It doesn't give you more power just because it's 93 vs 87.
Diesel engines operate by heat of compression. As the piston moves upward on the compression stroke the temperature in the combustion chamber rises. It's this rise in temperature alone that ignites the fuel and air mixture, because there is no spark plug to ignite it.
In gasoline engines we do NOT want this to happen. We need the fuel to be stable enough to withstand the heat and the amount it's being compressed so we have as much of the fuel there to ignite when the spark plug fires.
To put it simply if your engine is running fine with no pinging or knock-retard on 87, then you will see no gains or benefit from running 93. If you have an engine like an LS1, or other engine with higher compression and more aggressive timing tables, you will need to run higher octane.
Now here is where a lot of people get lost...the most power is made using the lowest octane without seeing pre-ignition. Use higher than you need, and you could actually lose power. I get funny looks from old school guys all the time when I tell them my 11.34-1 SCR heads/cam car runs perfect on 93, and that I have NEVER ran "racing" fuel in it.
Diesel engines operate by heat of compression. As the piston moves upward on the compression stroke the temperature in the combustion chamber rises. It's this rise in temperature alone that ignites the fuel and air mixture, because there is no spark plug to ignite it.
In gasoline engines we do NOT want this to happen. We need the fuel to be stable enough to withstand the heat and the amount it's being compressed so we have as much of the fuel there to ignite when the spark plug fires.
To put it simply if your engine is running fine with no pinging or knock-retard on 87, then you will see no gains or benefit from running 93. If you have an engine like an LS1, or other engine with higher compression and more aggressive timing tables, you will need to run higher octane.
Now here is where a lot of people get lost...the most power is made using the lowest octane without seeing pre-ignition. Use higher than you need, and you could actually lose power. I get funny looks from old school guys all the time when I tell them my 11.34-1 SCR heads/cam car runs perfect on 93, and that I have NEVER ran "racing" fuel in it.
Excellent post, should be a sticky. Especially the last point, that is very true even though it might seem counter intuitive. Are you talking about the Shell commercials underwater with everything fine and dandy because you used V-Power? You know that you are saving 1000s of clownfish each time you fill up with V-Power!
The only thing I can think of is that with cheaper gas there might be buffers that they use to cheapen it up. Like methanol or some other chemical. [Would that be cheaper though?] That would be the only way you might be less MPG from low test. But that means there are variables in this. Not comparing the same thing...
The only thing I can think of is that with cheaper gas there might be buffers that they use to cheapen it up. Like methanol or some other chemical. [Would that be cheaper though?] That would be the only way you might be less MPG from low test. But that means there are variables in this. Not comparing the same thing...
I haven't seen that commercial you're talking about but that sounds like something they would say. If you really want to help the environment, use the gas that will run most efficiently in your car. Better mileage=less pollution.
Joined: Nov 2001
Posts: 34,651
Likes: 2,577
From: Schiller Park, ILL Member: #317
If your friend can afford a '07 Lexus and uses 87 octane gas, he's probably just a cheap ***hole! 
My brother's '05 Audi states 91 octane fuel only. I bet your friend's car does too. 91 octane fuel is all that touches my '98 transam.
My brother's '05 Audi states 91 octane fuel only. I bet your friend's car does too. 91 octane fuel is all that touches my '98 transam. 