Which Octane gas are you using?

[BogsRam14]

89 but occasionally fill with 93 here and there.

 

[Mfabriz]

I run 89 as well .


Sent from my iPhone using Tapatalk

 

[Kotta390]

Whoever think that by using 93 octane is better because it is a cleaner fuel, needs to do more research on how octane rating is calculated and how it is designed. Run 87 or 89, whichever you prefer. The PCM will adjust for lower octane. Is it a BIG difference between the two?? NO.... If anything the performance is probably the same, but with 89 octane you will have less knock events, which means slithgly better fuel mileage and possibly slightly better performance depending on the area you live in. I can promise you it is NOT a noticeable difference. You MIGHT be able to measure it at the strip, but a 3-4mph gust going down the track will more likely offset the numbers then the octane of fuel.


I personally just run what the manufacturer recommends.

 

[Dubstep Shep]

93 on the race tune, but on the daily tune I'll run 87 or 89 depending on the time of year.

I also make sure to run e10. It's easier here in Texas because almost everywhere runs it now, but it's a lot cleaner for your fuel system, among other less pronounced benefits. The MPGs are a few percent lower, but most people wouldn't even notice it.

 

[Riccochet]

89 for daily commuting. 93 for towing.

 

[Bullitt279]

Switching to 89 to see if any difference

 

[SyN]

93 on the race tune, but on the daily tune I'll run 87 or 89 depending on the time of year.

I also make sure to run e10. It's easier here in Texas because almost everywhere runs it now, but it's a lot cleaner for your fuel system, among other less pronounced benefits. The MPGs are a few percent lower, but most people wouldn't even notice it.

Dubstep: is there anything out there information wise. That shows or proves that E10 gasoline runs and burns a lot cleaner than 100% gasoline?

I have seen actual pictures of a fuel system that has been run over 80,000 miles with E85 gasoline. The injector tips the valves the top of the Pistons were totally spotless. So I know that he 85 burns very very clean

I have heard a few owners talk about E10 burning cleaner but I never have actual seen proof.

 

[APFSDS]

i go back and forth from 89 to 87, but i also don't use crap gas. i'll drive past arco and no-name places to go to QT or Shell.

 

[Hemi395]

I usually do 89. I'll throw a tank of 93 in if its pure gas.

As far as brands go, I usually avoid the no name stations and try to hit Shell or Mobil/Exxon. If you really want the "best" gas search Top Tier Gasoline

 

[Rzrman328]

i go back and forth from 89 to 87, but i also don't use crap gas. i'll drive past arco and no-name places to go to QT or Shell.

I Know lots of guys that do this. including myself.

Maybe it's mental but I will easily pass a grungy, no name gas station for a chevron or mobil lol.

 

[Bigdaddy]

I run 92 octane when I tune it with my tuner but other time I run 87 octane with the tune.

 

[Dubstep Shep]

Dubstep: is there anything out there information wise. That shows or proves that E10 gasoline runs and burns a lot cleaner than 100% gasoline?

I have seen actual pictures of a fuel system that has been run over 80,000 miles with E85 gasoline. The injector tips the valves the top of the Pistons were totally spotless. So I know that he 85 burns very very clean

I have heard a few owners talk about E10 burning cleaner but I never have actual seen proof.

I can't say I have any documentation on me right now, but it's a helluva lot better than MTBE or any of the other octane additives they use in 100% gas.

 

[Medic4302]

Interesting. Following.

 

[Hemifatboy]

I've heard alcohol absorbs a lot of water plus it's very corrosive and breaks down any rubber it touches

 

[loveracing1988]

I've heard alcohol absorbs a lot of water plus it's very corrosive and breaks down any rubber it touches

While true, there hasn't been non alcohol resistant rubber in fuel systems in years.

 

[lagerstout]

Every tank is 89 octane.

 

[Dubstep Shep]

I've heard alcohol absorbs a lot of water plus it's very corrosive and breaks down any rubber it touches

That isn't exactly true... Water is technically an alcohol. What makes an alcohol an alcohol is the -OH that's attached to it. Water is actually the simplest alcohol that you could ever make, but because of that it never separates its -OH off and thus is never used like an alcohol.

Anyways, all alcohols will have that -OH and then something attached to it.

Hydrocarbons, on the other hand, have no Oxygen in them. They are a chain of Carbon atoms with Hydrogens at every joint where there isn't another Carbon.

What this means is that Alcohols tend to be polar molecules, like water, where as Hydrocarbons are non-polar. What I mean by polar is that one side of the molecule actually has a positive charge and the other side has a negative charge.

Essentially what this means is that with most alcohols, water will readily mix and combine with it and form a solution. Hydrocarbons, on the other hand, will not form a solution, but a mixture, meaning that the water will precipitate out of the mixture eventually.

What this means is that ethanol will actually "hold" onto the water and burn it with the fuel. 100% gas will not, however, and water buildup with gas can cause very serious issues with your vehicle.

While true, there hasn't been non alcohol resistant rubber in fuel systems in years.

This is also 100% true. All vehicles in the US must be compatible with at least 10% ethanol. Most have fuel systems that are capable of e85, even if the vehicle isn't tuned for it.

 

[Hemifatboy]

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

 

[GP4L]

Dubstep: is there anything out there information wise. That shows or proves that E10 gasoline runs and burns a lot cleaner than 100% gasoline?

I have seen actual pictures of a fuel system that has been run over 80,000 miles with E85 gasoline. The injector tips the valves the top of the Pistons were totally spotless. So I know that he 85 burns very very clean

I have heard a few owners talk about E10 burning cleaner but I never have actual seen proof.

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"

This has been my thoughts as well! Just because I push a selected button at the pump--->Do I actually Trust that I am getting that selected Octane that I am paying for? How many gallons are still in the pump from the previous buyer {Different Octane} that I am actually paying for that is Not My Selected Octane? It would be nice just to have 2 Octane selections again... Unleaded and Super Unleaded...

Years ago Super Unleaded was dyed Red! If you used a clear inline fuel filter-->You could actually see that you were running premium...

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...?

 

[Tray Burge]

Yeah, it doesn't hurt it, but it runs better with higher octane- I didn't buy mine for good gas mileage anyway. I always put Blue Stabil in it EVERY time I fill up to combat the Ethanol too.