Fuel quality vs. performance

[cobrajet84]

Even with a flex fuel truck i try to find non-ethanol fuel, have to pay a few cents more per gallon, but its worth it to me.

[MikeNH]

None around here that sell ethanol free fuel. I run E85 to maximize the benefit of the BlackBear tune. Plus at current prices it less per mile than premium.

 

 

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[Coalbunny]

Here the E-free is 88 octane and it goes for close to the same price as super unleaded. AFAIC it's worth it. I'm just not sure how long it will take before I notice a difference.

[TooTall1]

I have a Mills Fleet Farm here with 2 grades of ethanol free gas, 89 and 91 octane. The 89 is about 5 cents more a gallon than other stations sell their E10- 87 octane for.

[yukon25008.1]

I checked, there are none near me

[kstruckcountry]

I run with the lowest ethanol possible. My truck is flex, but I have never run e-85 and never will. I recognize ethanol for what it is: political posturing that is harming the ag industry and funneling money to the people doing the damage.

[Wires]

E85 is better for performance. It has an appx 107 octane rating. Correct on the milage though it drops. Ryan

 

Higher effective octane, but octane has nothing to do with performance unless you are running a super high compression engine, or one under a lot of boost. E85 has 25% less energy per gallon, which directly translate to a performance loss. (Obvious with the 25% worse fuel mileage).

[RyanbabZ71]

Higher effective octane, but octane has nothing to do with performance unless you are running a super high compression engine, or one under a lot of boost. E85 has 25% less energy per gallon, which directly translate to a performance loss. (Obvious with the 25% worse fuel mileage).

 

 

Feel free to come drive my truck so you can feel the difference between E85 and premium? It is noticable.

 

 

Use of E85 in an engine designed specifically for gasoline would result in a loss of the potential efficiency that it is possible to gain with this fuel. Use of gasoline in an engine with a high enough compression ratio to use E85 efficiently would likely result in catastrophic failure due to engine detonation, as the octane rating of gasoline is not high enough to withstand the greater compression ratios in use in an engine specifically designed to run on E85. (However, Flex Fuel Vehicles are designed to run on any mixture of gasoline and ethanol, from pure gasoline to E85, and avoid this problem.) Using E85 in a gasoline engine has the drawback of achieving lower fuel economy, as more fuel is needed per unit air (stoichiometric ratio) to run the engine in comparison with gasoline. The additional ethanol required for a stoichiometric fuel ratio helps compensate for lack of energy provided by ethanol's lower heating value (LHV), which is lower than the LHV of gasoline.

[Chris]

I'm booking my flight Ryan. You have full coverage right?

 

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[MikeNH]

Higher effective octane, but octane has nothing to do with performance unless you are running a super high compression engine, or one under a lot of boost. E85 has 25% less energy per gallon, which directly translate to a performance loss. (Obvious with the 25% worse fuel mileage).

 

 

Doesn't make less power cause the engine just uses more of it. Then the higher octane allows for more aggressive timing to be used. Not to mention by my calculations it is currently less expensive to run than premium, which is nice given the cost of fuel these days to have whatever break you can get. I just wish GM could make the gas tank bigger like the F-150 and Ram. 32-36 gallons would be kickass because it would help offset the lousy range with E85 and when I did run premium (as I would to go back east to visit the parents) I'd have amazing range compared to now.

[Wires]

Timing an octane doesn't make extra power. Both are myths that plaque the engine and automobile industry.

 

There is no way the engine could use an engine that would utliize high enough compression to get maximum power out of E85 and not explode on gasoline. The power difference is much like switching a propane grill to natural gas. You need a much large jet for NG to get enough fuel out to get similar heat. Yet, a NG grill tends to still grill cooler than propane.

 

The otto style engine (in everything except the wankle style rotary in the RX-8) is found in basically every vehicle on the planet. The design is pretty simple: Piston sucks in air/fuel, compresses it and then a spark lights the mixture which blows the piston back down making power.

 

In order to get the harvest the maximum amount of energy out of that down stroke, you need that full ignition just after TDC (Top Dead Center). The issue is depending on how much throttle, the engine design, temperature, etc, it takes a bit of time for the mixture to light, and reach that full ignition. This is where the timing comes in. The plug is fired early (aka timing advance), so as the piston starts cresting over TDC, the mixture is fully lit and it can push the piston back down. If you light the plug too early, then you get a "ping" or detonation, since the mixture is full lit on the upstroke, and it's trying to stop the piston. Too far, and you blow a hole in the piston.

 

In a higher compression engine, running higher octane prevents that pre-ignition by slowing the flame kernel front. But running higher octane and more advance isn't going to get you more power (unless the engine design was so poor that the flame kernel propagation in the engine was incrediabley slow).

 

But at the end of the day, the amount of HP that engine can produce is equal to the how many lbs/hr of fuel can be burnt in it, as well as the energy/lb of the fuel being consumed.

 

If you're losing 25% fuel economy, then you're not gaining power, you're losing it. Regardless of what the butt-dyno says.

[MikeNH]

You don't lose power with E85. This is fact. GM advertises a 10 or 15 HP gain from E85 on the LC9 5.3 and that is SAE Certified, so it isn't something they pulled out their backside.

[kstruckcountry]

Usable power increases with ethanol. Power per gallon decreases.

[Wires]

Still would like to see the dyno plots comparing the same engines, on the two fuels. Not like GM would ever lie about anything. Much like Dodge's commerical with their 36MPG 1/2 ton in Canada.....

 

Still pegging money on them just bumping up the rev limiter on the E85 fuel to give "more power". My 6.2L couldn't even get GM's HP rating because they put a lower rev limiter from the factory. Wasn't until I did a Wester's tune did I get the avertised HP rating.

 

So is that GM being honest or a lie???

 

At the end of the day, run E85 if you want to do something good for the planet since it burns cleaner. But if I have to pay the same $/gallon for gas as inferior E85, I'll burn the dino oil....

[MikeNH]

It's tested per SAE guidelines and the graphs are on GMpowertrain.com. The manufacturers won't pad power figures, there are too many high profile cases where the automakers have been burned by bumping power figures. Go look for yourself, I'm not going to even attempt that site on my phone. As for the Ram commercial, I don't care what Ram does, especially in Canada.

 

 

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