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I was just wondering, to settle a conversation, if a engine that has been designed to use 87 octane was running on 93 what would be the drawbacks (besides the cost)? I had heard that a small amount of power would be lost due to the full ignition of the fuel would be in the 'exhaust cycle' of the engine. Any truth to that?

No not really any cumbustion in the exhaust cycle. But not any real gain unless you have some timing or fuel and air controller.
Higher octane burns slower letting you advance the timing safely. That is the benefit, but only in conjunction with the afore mentioned parts.

high octane allows u to get better mpg well least ive noticed with my storm. also little more get up and go. cost sucks, but if u turbo or nos your mx3 u should run high octane to prevent detantion.

but in cars such as the newer 2.0 "neon's" it is rated for the 85 octane and will actually perform worse with the higher octane. but with most cars it doesn't matter, it is just that the computer doesn't agree with the octane level on some cars

yep but basicly if higher octane didnt do something or wasnt required no need to have it for sell, but good idea to run 91-93 octane with turbo or nos setups

higher octane is useless in our cars. Unless you've tuned it for the higher octane it does nothing for you except empty your wallet faster. Keep buying it if you want but you dont get any improvements whatsoever from it.

Everyone in the world seems to say "I get better MPG with higher octance and my car is faster", is think thats a load of crap. I have never noticed an increase in MPG using a higher octance then specified, Although I have noticed that using a lower octane then the manufacturer recommends will worsen MPG and power <retards timing> for the average econobox the only benefit from higher octane will be a lightened wallet - unless you have the mods to use the higher octane. Although in some rare cases higher octance can be a benefit - The SCC 350z dyno results show that a higher octane did gain a few HP IIRC.

Octane # just mean how easily the gas burns. Do the math.

Test your mileage. My dad's civic got enough more mileage to make up for the increased price.

The higher the octane, the more resistant it is io predetonation, and the slower burning it is. Your car will run the best with the least amount of octane required.

People think their cars run better with high octane because they paid more for it. A car is designed to work for a certain octane. When you put higher in, it hurts you more than helps you. There is more additives in the higher octane fuels at the pump to clean your engine out etc.. Performance wise, you are hurting yourself. Unless you are in a situation where you are detonating you don't need a higher octane.

slowmx3 wrote:People think their cars run better with high octane because they paid more for it. A car is designed to work for a certain octane. When you put higher in, it hurts you more than helps you. There is more additives in the higher octane fuels at the pump to clean your engine out etc.. Performance wise, you are hurting yourself. Unless you are in a situation where you are detonating you don't need a higher octane.

What do you attribute the increase in power and performance in vehicles that have the opportunity and use a really high octane (106 octane) race gas on their street vehicles when on the track? Your partially right ... cars are designed to work for a certain minimum octane. The key word here is minimum. When you put higher in, it does not hurt more than it helps you. What more additives are you refering to? If you're refering to the possibility of a possible ethanol content of 10%, I'm more than happy to see that in there. You're absolutely right that if you encounter pinging (detonation), switching to a higher octane is a good alternative.

PATDIESEL wrote:No not really any cumbustion in the exhaust cycle. But not any real gain unless you have some timing or fuel and air controller.
Higher octane burns slower letting you advance the timing safely. That is the benefit, but only in conjunction with the afore mentioned parts.

i am with him on this one

jschrauwen wrote:

slowmx3 wrote:People think their cars run better with high octane because they paid more for it. A car is designed to work for a certain octane. When you put higher in, it hurts you more than helps you. There is more additives in the higher octane fuels at the pump to clean your engine out etc.. Performance wise, you are hurting yourself. Unless you are in a situation where you are detonating you don't need a higher octane.

What do you attribute the increase in power and performance in vehicles that have the opportunity and use a really high octane (106 octane) race gas on their street vehicles when on the track? Your partially right ... cars are designed to work for a certain minimum octane. The key word here is minimum. When you put higher in, it does not hurt more than it helps you. What more additives are you refering to? If you're refering to the possibility of a possible ethanol content of 10%, I'm more than happy to see that in there. You're absolutely right that if you encounter pinging (detonation), switching to a higher octane is a good alternative.

Actually, it depends on the car's computer. I've seen tests where cars lost power going from 87 to 93. But I've also seen where it gains a few. But the gains are minimal either way on a normally aspirated engine. More gains can be had running higher octane than the owner's manual says if you're running turbo or supercharger.

With my compression being low on my car, last week i decided to try a tank 87 to see what would happen...man, it drank that like water