Run a tank of 91+ in your 6.0.

sdeeter19555 · February 13, 2017

It isn't practical to run e85 in some locations...around here it's hard to find and almost the cost of regular unleaded.

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Colossus · February 13, 2017

Who gives a dang about cost? it's the fun/performance factor when you run E-85 and the truck has some get up and go. (Same with 91+)

Cowpie · February 14, 2017

It isn't practical to run e85 in some locations...around here it's hard to find and almost the cost of regular unleaded.

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So true. It is more a regional thing.

KMK454 · February 14, 2017

I ran 91 and noticed no difference other than it being more expensive. I even filled up when the tank was on E, so it wasn't mixing with lower octane fuel.

4wdriver · February 14, 2017

I ran 91 and noticed no difference other than it being more expensive. I even filled up when the tank was on E, so it wasn't mixing with lower octane fuel.

Same here

4x4Pete · February 14, 2017

I noticed the 5.3 in the 1500 seemed to run and idle better. The 6.0 seems less responsive to high octane. It idles and runs the same on either grade.

EZTundra77 · December 15, 2018

So I am genuinely curious if anyone has dynoed 87 vs 93 octane in a stock L96. Never underestimate the perceptions of the butt dyno. IF there an actual performance increase, then that increase is worth exactly what someone is willing to pay for it. I was an avid 93 V-power junky. But since nobody has ever actually shown numbers from a dyno, I can justify 80¢/gal more. I do believe V-Power cleans the fuel system better, so I bought a case of Chevron with Techron and Run a bottle every other month for cleaning. At 10k miles a year, the diff between 87 and 93 is about $700/year (12 MPG). That's a big cost. Over 10 years, that's the cost of a supercharger and a few pro fuel system cleaning

SierraHD17 · December 15, 2018

I have never dynoed my truck because honestly it's a waste of money for something underwhelming.. somebody want's to pay for my dyno time sure.... otherwise no.

That said I must be the only one to actually datalog his truck prior and aft of tuning it. I will say this about my 2017 L96.

Prior to tuning or logging I ran 87 octane from whatever gas station. The truck actually got the best fuel economy it has ever gotten on 87 gas and of course the truck was totally stock at that point. So prior to tuning I pulled out HP and logged some data. On a bunch of WOT pulls and whatever else I could do I lost no timing to pre-igntion with 87. Now the ECM stock has some safe guards like a burst knock feature where it just pulls timing immediately on a large throttle transition. That said at the whopping 18 or 19 degrees of full throttle advance it still didn't knock on 87. Pretty safe to say to you can run 87 and gain nothing going to a higher octane fuel with the stock tune.

However after adding even 2 to 3 degree's of timing the truck started to knock on 87... but I also disabled burst knock. So let's say I had left the stock tune alone minus the anti knock features on throttle transition would I have seen knock? Probably.

After that however I jumped the truck to 94 octane with 10% ethanol or 91 octane without and have not seen any notable knock since even with 30 degrees of ignition timing. I don't have 30 written in the table but there are timing adders that add to the stock table. I run premium all the time now as I do not consider the price change in the gas consequential. If E85 was available I may run it but I don't like the system this ecm uses to determine alcohol content and honestly may as well disable it.

The factory spark table is so weak for non ethanol that it would be hard pressed to do anything knock wise on low octane fuel. I don't like how ethanol content is inferred on these as they have no actual sensor like the 2014+ ethanol optioned half tons do. It's a half assed way of doing things that like the prior GMT900 flex fuel trucks have experienced can lead to the ecm doing strange things and causing issues. Oh well. These heads don't need 30 degrees..... probably 26 would be lots but I really don't care as I don't have any issues set how I am.

Edited December 15, 2018 by SierraHD17

EZTundra77 · December 15, 2018

1 hour ago, SierraHD17 said:

I have never dynoed my truck because honestly it's a waste of money for something underwhelming.. somebody want's to pay for my dyno time sure.... otherwise no.

That said I must be the only one to actually datalog his truck prior and aft of tuning it. I will say this about my 2017 L96.

Prior to tuning or logging I ran 87 octane from whatever gas station. The truck actually got the best fuel economy it has ever gotten on 87 gas and of course the truck was totally stock at that point. So prior to tuning I pulled out HP and logged some data. On a bunch of WOT pulls and whatever else I could do I lost no timing to pre-igntion with 87. Now the ECM stock has some safe guards like a burst knock feature where it just pulls timing immediately on a large throttle transition. That said at the whopping 18 or 19 degrees of full throttle advance it still didn't knock on 87. Pretty safe to say to you can run 87 and gain nothing going to a higher octane fuel with the stock tune.

However after adding even 2 to 3 degree's of timing the truck started to knock on 87... but I also disabled burst knock. So let's say I had left the stock tune alone minus the anti knock features on throttle transition would I have seen knock? Probably.

After that however I jumped the truck to 94 octane with 10% ethanol or 91 octane without and have not seen any notable knock since even with 30 degrees of ignition timing. I don't have 30 written in the table but there are timing adders that add to the stock table. I run premium all the time now as I do not consider the price change in the gas consequential. If E85 was available I may run it but I don't like the system this ecm uses to determine alcohol content and honestly may as well disable it.

The factory spark table is so weak for non ethanol that it would be hard pressed to do anything knock wise on low octane fuel. I don't like how ethanol content is inferred on these as they have no actual sensor like the 2014+ ethanol optioned half tons do. It's a half assed way of doing things that like the prior GMT900 flex fuel trucks have experienced can lead to the ecm doing strange things and causing issues. Oh well. These heads don't need 30 degrees..... probably 26 would be lots but I really don't care as I don't have any issues set how I am.

If I did mods or noticed knock, I would run higher octane. Otherwise, I think your conclusion is in line with my guess...which is that stock engines that call for 87 can run 87 while getting full performance. But I am open to data stating otherwise. I'm not asking for a dyno sheet to confirm my suspicion. Rather one to the contrary. I would love to see dyno sheet that showed any HP increase with 93.

EZTundra77 · December 16, 2018

Also, can I confirm that E85 makes more power? I was under the impression it made less power. I know you have to change your oil twice as often if you run E85. That extra oil change cost should also be factored in the overall difference in price of E85

SierraHD17 · December 16, 2018

There was a dyno sheet from Diablo I think if you look on their website for these. The stock E85 tune showed a 25 or 30 hp increase which makes sense. The ecm adjusts for the new stoich value as you increase the alcohol content and then the alcohol adder dumps some ignition timing into the main spark table you will not see on normal gas. It's just all the timing lol. Really i think their premium gas tune and e85 tune were pretty close to the same numbers.

Edited December 16, 2018 by SierraHD17

cmysstailights · December 17, 2018

There was a dyno sheet from Diablo I think if you look on their website for these. The stock E85 tune showed a 25 or 30 hp increase which makes sense. The ecm adjusts for the new stoich value as you increase the alcohol content and then the alcohol adder dumps some ignition timing into the main spark table you will not see on normal gas. It's just all the timing lol. Really i think their premium gas tune and e85 tune were pretty close to the same numbers.

I ran bully dog on my 6.0 and e85 gas. Was told 93 tune would work. Truck ran worse and towed worse. Went back to stock tune and e85. Now looking into blackbear tune since they said their tune will let me run e85 or 87 just like factory

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SierraHD17 · December 17, 2018

Bullydog junk is garbage... you just learned why you don't run a snakeoil handheld that improves nothing.

I would not waste my time with 87 octane fuel tuning. You will gain some drivability but you will gain almost absolutely zero power from stock...

Edited December 17, 2018 by SierraHD17

cmysstailights · December 17, 2018

I run primarily e85. I was told by them that the 93 tune would work with e85. Boy they were wrong, live and learn. Only reason why i am looking at e85/87 tune is i tow 12k lbs. I usually carry 20gallons extra for return trip home. But there will be other trips that are further and cant be locked into just e85 which is readily available by me but not when traveling.

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Cowpie · December 22, 2018

One of the aspects to E85 is that it cools the intake air into the cylinder, which makes the air in the combustion chamber more dense. That leads to a more efficient burn. It is one of the aspects that allows some engine developers to run significantly higher compression ratios in E85 specific engines like the Cummins Ethos engine and the Ricardo 3.6 EBDI engine.

One thing for certain, there are significantly lower combustion deposits with higher blends of ethanol. There is a pretty good video on this, and ethanol use in general. Covers blends of methanol, ethanol, and pure gas and wear on engines. One thing that many use as a claim against ethanol... formation of formaldehyde and such... is actually an issue with Methanol, not Ethanol.

Edited December 22, 2018 by Cowpie