Which Octane gas are you using?

[SlowRoller]

Please describe 'runs better',,,

 

[Dubstep Shep]

alot of us have old vehicles with old rubber and gaskets that don't like ethanol , and the water in ethanol causes corrosion in fuel lines and tanks and wherever else it can , I'll use 100% gas whenever I can , there's plenty of that ethanol crap out there for anyone that wants it , I'm sure someone will find something to correct on this post , Jeeze

Sure, the older vehicles may have fuel system components that were not designed to work with ethanol.

But again, ethanol doesn't hold a different amount of water than gasoline does. It's not like ethanol somehow magically makes water appear inside your tank. Ethanol absorbs the water and holds it mixed in with the fuel. Gasoline does not, and will allow the water to separate out.

If you want to run 100% gas, that's fine, but you should know it isn't what 100% gas used to be. The additives they use to bring the octane rating up have changed, which is a big reason why gas companies use ethanol now: It's cleaner.

E10 = 10% Ethanol, 90% gasoline. will you visually notice a cleaner combustion chamber? in the real world, no. in a test lab, probably. - My personal experience as an engine builder for 10 years. E85 (race) engines are usually "cleaner". The biggest shortcoming of E85 (at gas stations) was the inconsistency of Ethanol %. It would vary between 85% and 90%, which throws the fuel and ignition mapping off. My last performance car (Evo 8) would need its tune touched up nearly every tank. Yes, there was a laptop in the car at all times, lol. The wording on most 10% Ethanol pumps should say something like "gas contains *up to* 10% Ethanol added"

I've never seen e85 out of the pump be any higher than about 84% ethanol. In the winter you're lucky to get 50%.

This is where flex fuel vehicles are awesome. Because the stoichiometric ratio change is linear with the change in the alcohol content, you can make a tune for 100% gas, make a tune for 100% alcohol, then add a flex fuel sensor and the computer will interpolate between the two tunes.

 

[Hemifatboy]

It's not magic , how cute , Google ethanol attracts and absorbs water even from the air , I've been reading this crap since they came out with gasahol , it's a dumb idea and causes a lot of mechanical issues , plus were burning our food to subsidize the farm and corn lobby

 

[John94z]

Didn't bother reading but in 5 pages in sure someone has pointed out that you won't get more fuel savings running a higer octaine fuel nor will you see hp gains. The only thing high octaine fuel does is prevent detonation on high compression engines. The hemi isnt really that high and idk about you but I don't race my truck. I use 87. Any more and you are wasting your money.
* disclaimer- I know someone will respond saying they used 92 octaine and saw such and such results etc.
No you didnt, it's all in your head. Any improvements you saw were from other coincidental conditions.

 

[Hemifatboy]

Agreed John and it's even worse , the slower more controlled burn of higher octane gas can cause incomplete burn if the engine can't compensate enough and you could actually get worse gas mileage

 

[iam_canadian22]

E10 = 10% Ethanol, 90% gasoline. will you visually notice a cleaner combustion chamber? in the real world, no. in a test lab, probably. - My personal experience as an engine builder for 10 years. E85 (race) engines are usually "cleaner". The biggest shortcoming of E85 (at gas stations) was the inconsistency of Ethanol %. It would vary between 85% and 90%, which throws the fuel and ignition mapping off. My last performance car (Evo 8) would need its tune touched up nearly every tank. Yes, there was a laptop in the car at all times, lol. The wording on most 10% Ethanol pumps should say something like "gas contains *up to* 10% Ethanol added"



Gas stations have to guarantee you are getting "at least XX octane". If you can PROVE that they didn't sell you what you paid for, you can take some form of legal action.

Bad gas was the 3rd leading cause of detonation related engine failure in the EJ257 and 4G63 (Subaru STI and Evolution 1-9) engines that I've rebuilt over the years. Granted, this was in a very high performance application, and the first and 2nd causes were the "kill tune" (very hot tune with knock control turned off), and the owners turning up the boost past what their vehicle was built and tuned to handle. (yes, guys actually did do that ALL the time)

Point is - getting bad gas DOES happen. However, I saw it frequently due to the nature of my job. In reality, the first two causes of engine failure related to DET were WAY ahead of bad gas.

Most of our Hemi's are tuned for 89 from the factory. Running 87 will be ok under normal driving conditions, but the ECU WILL pull out some ignition timing to compensate for the lower detonation resistance 87 has.

Auto's 101 says (simplified) that ignition timing advance is used to generate more cylinder pressure (which is what obviously drives the piston down, making torque), as compensation for lower Volumetric Efficiency (VE). Wasted energy needs to (try to) be compensated for (pretty much every production engine on the planet needs to compensate for poor VE). Taking some of that ignition advance away (because the lower octane can't handle the pressure (heat)) usually results is lower torque. I say "usually" because the timing has to be retarded past a certain point (MBT - for those of you who know what that is) before the quicker burn stops compensating for the less advanced ignition timing - which the timing is usually pulled back enough to rob the engine's torque production, lowering overall VE = more energy wasted = more fuel needed to do the job.

https://www.youtube.com/watch?v=sEf8va1S7Sw

This is a cool video to note when the spark plug fires. Pay attention to where the piston is when the mixture is ignited.

On the flip side, running 91/92/93/94 (whatever you have), won't yield much, if any, benefit without being tuned for it. Higher octane resists detonation more (takes more heat and pressure to get it to ignite on its own), and the byproduct is, it takes a little longer to complete its burn. So without the ignition timing advance to compensate for that, it might not do anything good for you. In less common cases, engines might actually lose power because the piston is at the end of its power stroke (Bottom Dead Center), before the air/fuel burn generated its maximum pressure (torque). But, I have no idea if this happens on our trucks.

Bottom line - run the fuel that you're tuned for. Especially if you tow/haul, or see WOT frequently. I run 89. Once the usually ****** winter blend arrives in the Chicago area, I'll probably spike my gas with 5-10 gallons of 93. My experience with V-8's tell me that I probably wont notice any benefit, and I'll stop throwing cash away at the pump.

Sorry if I lost anybody, stopped making sense, or said something inaccurately... I'm not sure if I've had too much coffee this morning, or not enough...?

Our pumps do say up to##

 

[Rzrman328]

I know someone will respond saying they used 92 octaine and saw such and such results etc.
No you didnt, it's all in your head. Any improvements you saw were from other coincidental conditions.

 

[bassheadhemi]

From the owners manual

DO NOT use gasoline containing Methanol or gasoline
containing more than 10% Ethanol. Use of these
blends may result in starting and drivability problems,
damage critical fuel system components, cause
emissions to exceed the applicable standard, and/or
cause the “Malfunction Indicator Light” to illuminate.
Please observe pump labels as they should
clearly communicate if a fuel contains greater than
10% ethanol.

Problems that result from using gasoline containing
Methanol or gasoline containing more than 10% ethanol
are not the responsibility of the manufacturer and may
void or not be covered under New Vehicle Limited
Warranty.

So be careful not using E15 in an Hemi Ram.

Also the argument where ethanol is not bad in modern cars because the tank doesn't vent to atmosphere is crap. Humidity is getting inside the storage tank at the station and since most of them are directly vented to atmosphere you can be sure that fresh air is rushing inside the vent pipe as the pumps are filling cars. Yes some will have pressure/vacuum valve, but it is a minority.

 

[GP4L]

Sure, the older vehicles may have fuel system components that were not designed to work with ethanol.

But again, ethanol doesn't hold a different amount of water than gasoline does. It's not like ethanol somehow magically makes water appear inside your tank. Ethanol absorbs the water and holds it mixed in with the fuel. Gasoline does not, and will allow the water to separate out.

If you want to run 100% gas, that's fine, but you should know it isn't what 100% gas used to be. The additives they use to bring the octane rating up have changed, which is a big reason why gas companies use ethanol now: It's cleaner.



I've never seen e85 out of the pump be any higher than about 84% ethanol. In the winter you're lucky to get 50%.

This is where flex fuel vehicles are awesome. Because the stoichiometric ratio change is linear with the change in the alcohol content, you can make a tune for 100% gas, make a tune for 100% alcohol, then add a flex fuel sensor and the computer will interpolate between the two tunes.

Back in 2006-09 E85 was usually at least 85%. Winter blend was usually 70%.

 

[GP4L]

Our pumps do say up to##

Same here.

 

[Dubstep Shep]

It's not magic , how cute , Google ethanol attracts and absorbs water even from the air , I've been reading this crap since they came out with gasahol , it's a dumb idea and causes a lot of mechanical issues , plus were burning our food to subsidize the farm and corn lobby

I'm going to address your claims with reason and facts, and my hope is that you'll do likewise.

I'm well aware of how ethanol absorbs water. It doesn't "attract" it though. It simply will mix with the water completely to form a solution, rather than forming a mixture like water and gasoline will. Gasoline will allow the water to precipitate out rather than holding onto it.

What this means is that ethanol will essentially hold the water and burn it with the fuel, whereas gasoline will allow the water to pool separately from the gasoline. That can cause major issues.

E10 will hold some water, but the ethanol/water will precipitate out from the gasoline. This is where some people think that e10 will cause the water to separate out. It's not the separation of the water, it's the separation of the ethanol/water solution from the gasoline.

As for mechanical issues, that only occurs in older vehicles or those that are not tuned for ethanol. A modern vehicle will have zero issues running e10, many have no issues running e85, and the vehicle will run cleaner than on 100% gas.

Finally, the government subsidy for ethanol ran out awhile back.

From the owners manual


So be careful not using E15 in an Hemi Ram.

Also the argument where ethanol is not bad in modern cars because the tank doesn't vent to atmosphere is crap. Humidity is getting inside the storage tank at the station and since most of them are directly vented to atmosphere you can be sure that fresh air is rushing inside the vent pipe as the pumps are filling cars. Yes some will have pressure/vacuum valve, but it is a minority.

E15 is not tuned for in the truck, which is why you shouldn't run it.

As for the other argument, again, ethanol becomes a solution with the water, whereas gasoline will allow it to precipitate out. What that means is that no matter what portion of fuel you get from the tank, the % mix will be the same between the water and ethanol. With gasoline, you could get 100% gasoline or 100% water depending on where you pull from in the tank. The amount of water total in the tank will not change.

 

[Dubstep Shep]

Back in 2006-09 E85 was usually at least 85%. Winter blend was usually 70%.

I've tested at a lot of different pumps and never seen more than 84. They have to go really low in a lot of circumstances because it can be difficult to start in really cold climates.

 

[GP4L]

I've tested at a lot of different pumps and never seen more than 84. They have to go really low in a lot of circumstances because it can be difficult to start in really cold climates.

Yep, I learned that the hard way in 2006

Back then, E85 didn't suck like it does now.

 

[Selcher]

Using nothing but 91 for about 14 years now...

 

[Hemifatboy]

I'm going to address your claims with reason and facts, and my hope is that you'll do likewise.

I'm well aware of how ethanol absorbs water. It doesn't "attract" it though. It simply will mix with the water completely to form a solution, rather than forming a mixture like water and gasoline will. Gasoline will allow the water to precipitate out rather than holding onto it.

What this means is that ethanol will essentially hold the water and burn it with the fuel, whereas gasoline will allow the water to pool separately from the gasoline. That can cause major issues.

E10 will hold some water, but the ethanol/water will precipitate out from the gasoline. This is where some people think that e10 will cause the water to separate out. It's not the separation of the water, it's the separation of the ethanol/water solution from the gasoline.

As for mechanical issues, that only occurs in older vehicles or those that are not tuned for ethanol. A modern vehicle will have zero issues running e10, many have no issues running e85, and the vehicle will run cleaner than on 100% gas.

Finally, the government subsidy for ethanol ran out awhile back.



E15 is not tuned for in the truck, which is why you shouldn't run it.

As for the other argument, again, ethanol becomes a solution with the water, whereas gasoline will allow it to precipitate out. What that means is that no matter what portion of fuel you get from the tank, the % mix will be the same between the water and ethanol. With gasoline, you could get 100% gasoline or 100% water depending on where you pull from in the tank. The amount of water total in the tank will not change.

Quote " methanol and ethanol are hydroscopic they attract and absorb water "
That seems clear to me
Check into phase separation in gasohol and the problems it can cause , these are separate from the other reasons not to use it in an older vehicle

 

[Hemifatboy]

And as far as gov subsides they haven't given in , they are determined to make us use more ethanol , incentives , tarrifs , and forcing gas stations to use more ethanol pumps , the epa is involved now , that means it never goes away , they will make us like it

 

[Hemifatboy]

By the way I almost always use 89 octane and I'm done with this thread , believe whatever you like

 

[sbuko213]

I'm using 91 because the DS tune I'm running right now, and that's the highest I can get down here.

 

[TruckNut]

89 octane unless it's a cheaper brand of gas like Costco or Kroger. When there I fill with the best they have, usually 91.

 

[FXCLM5]

89 octane unless it's a cheaper brand of gas like Costco or Kroger. When there I fill with the best they have, usually 91.

believe it or not Costco is actually a Tier 1 like Chevron, Shell etc

I always thought it was a Tier 2 where their additives are not as controlled.