Premium or regular unleaded?
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From: No. Platte NE
Because when they run that octane, the engine [computer] is tuned to give more power because the higher octane will keep detonation from happening. If I filled up my Mustang with 100 octane, it will not all of a sudden have a gain of 20 HP. I have my computer tuned to run with 91 octane vs 87 for some HP gain. I HAVE TO run 91 or higher octane with the tune or there will be trouble. The reason a car on 91 octane could make, say, 500HP, but on 100 octane, can make 700HP. Statistically, you are wasting money.
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From: Northern California
It may not seem like it, but if you take use extra dollar or two at every fill up times how many times you fill it up in say, a year...
I feel you on the truck. My F150 has two 20 gallon tanks. That is a fun visit to the gas station if I fill them both up.
I feel you on the truck. My F150 has two 20 gallon tanks. That is a fun visit to the gas station if I fill them both up.
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From: Atlanta, GA
I'm trying to get my car ready to go full-synthetic soon.
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I have seen (meaning I did not say it or come up with it, so think about that before you ask me where I came up with it) that E85 has an octane rating of 105. If your car is tuned for it, performance wise, it would allow you more power due to the octane rating.
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I have filled up my Neon 2 times in the past month. Verses about 5 times in the truck. I feel that the Neon enjoys the more expansive gas over the 89 so I do it. Its still only a $20 trip to the pump max. But ya, your definatly right paying a dollar more every fill up deffinatly does add up.
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Maybe one tank wouldn't kill it, but put only e85 in there and you'll eventually have a fuel pump go out or some materials in the fuel system break down and deteriorate. Yes, depending on where you fill up, E85 at a station may go anywhere from 100 octane to 105. The mixtures are different depending on what the station has thus the fluctuation of the octane rating. Since most cars can't run e85, though, you'll see people trying other means like octane boosters or racing fuel before hitting the track or drag strip, right?
Yes, you will get more power from e85 in a car that can run it. Its a better, cleaner burn that allows for more 'head room' with the car's overall performance because the car won't dumb down the timing to prevent knocking or pinging. The key is to find what fuel works for your car the best.
http://en.wikipedia.org/wiki/Octane_rating
However, burning fuel with a lower octane rating than required by the engine often reduces power output and efficiency one way or another. If the engine begins to detonate (knock), that reduces power and efficiency for the reasons stated above. Many modern car engines feature a knock sensor – a small piezoelectric microphone which detects knock, and then sends a signal to the engine control unit to retard the ignition timing. Retarding the ignition timing reduces the tendency to detonate, but also reduces power output and fuel efficiency.
The rest of the 'stuff that matters':
It might seem odd that fuels with higher octane ratings are used in more powerful engines, since such fuels explode less easily. However, an explosion is not desired in an internal combustion engine. An explosion will cause the pressure in the cylinder to rise far beyond the cylinder's design limits, before the force of the expanding gases can be absorbed by the piston traveling downward. This actually reduces power output, because much of the energy of combustion is absorbed as strain and heat in parts of the engine,[citation needed] rather than being converted to torque at the crankshaft.
A fuel with a higher octane rating can be run at a higher compression ratio without detonating. Compression is directly related to power (see engine tuning), so engines that require higher octane usually deliver more motive power. Engine power is a function of the fuel, as well as the engine design, and is related to octane rating of the fuel. Power is limited by the maximum amount of fuel-air mixture that can be forced into the combustion chamber. When the throttle is partially open, only a small fraction of the total available power is produced because the manifold is operating at pressures far below atmospheric. In this case, the octane requirement is far lower than when the throttle is opened fully and the manifold pressure increases to atmospheric pressure, or higher in the case of supercharged or turbocharged engines.
Many high-performance engines are designed to operate with a high maximum compression, and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.
A fuel with a higher octane rating can be run at a higher compression ratio without detonating. Compression is directly related to power (see engine tuning), so engines that require higher octane usually deliver more motive power. Engine power is a function of the fuel, as well as the engine design, and is related to octane rating of the fuel. Power is limited by the maximum amount of fuel-air mixture that can be forced into the combustion chamber. When the throttle is partially open, only a small fraction of the total available power is produced because the manifold is operating at pressures far below atmospheric. In this case, the octane requirement is far lower than when the throttle is opened fully and the manifold pressure increases to atmospheric pressure, or higher in the case of supercharged or turbocharged engines.
Many high-performance engines are designed to operate with a high maximum compression, and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.
Last edited by add|ct; Aug 7, 2009 at 11:14 AM.
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Well, sure but if you ran that stuff in an unconverted car you're crazy.
Maybe one tank wouldn't kill it, but put only e85 in there and you'll eventually have a fuel pump go out or some materials in the fuel system break down and deteriorate. Yes, depending on where you fill up, E85 at a station may go anywhere from 100 octane to 105. The mixtures are different depending on what the station has thus the fluctuation of the octane rating. Since most cars can't run e85, though, you'll see people trying other means like octane boosters or racing fuel before hitting the track or drag strip, right?
Yes, you will get more power from e85 in a car that can run it. Its a better, cleaner burn that allows for more 'head room' with the car's overall performance because the car won't dumb down the timing to prevent knocking or pinging. The key is to find what fuel works for your car the best.
http://en.wikipedia.org/wiki/Octane_rating
Thus, cars with flex fuel not getting the benefits of the higher octane e85 if they can't compress at the higher ratio and the engine retarding the ignition timing. One solution could be getting an Ignition Control Module, but if the cars PHYSICALLY can not compress higher it will have its limits. See the foreign versions of flex fuel cars that have the ability to compress at the higher ratio on e85.
The rest of the 'stuff that matters':
Maybe one tank wouldn't kill it, but put only e85 in there and you'll eventually have a fuel pump go out or some materials in the fuel system break down and deteriorate. Yes, depending on where you fill up, E85 at a station may go anywhere from 100 octane to 105. The mixtures are different depending on what the station has thus the fluctuation of the octane rating. Since most cars can't run e85, though, you'll see people trying other means like octane boosters or racing fuel before hitting the track or drag strip, right?
Yes, you will get more power from e85 in a car that can run it. Its a better, cleaner burn that allows for more 'head room' with the car's overall performance because the car won't dumb down the timing to prevent knocking or pinging. The key is to find what fuel works for your car the best.
http://en.wikipedia.org/wiki/Octane_rating
Thus, cars with flex fuel not getting the benefits of the higher octane e85 if they can't compress at the higher ratio and the engine retarding the ignition timing. One solution could be getting an Ignition Control Module, but if the cars PHYSICALLY can not compress higher it will have its limits. See the foreign versions of flex fuel cars that have the ability to compress at the higher ratio on e85.
The rest of the 'stuff that matters':
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From: Atlanta, GA
Yeah, if it wasn't so much for an aftermarket conversion I may think about going flex-fuel, but its just not worth it. Its ridiculous that in other countries the flex fuel cars can run E100! w00t!
