2008 Gmc Sierra 5.3 LC9 on E85

[Richiefcknrich]

Hello every one,
I been searching around for a few days trying to find out if I can run E85 with my diablo intune tunner...
I have had the premium fuel tune on the truck for 5 years and I love it works great no issues, I was just wondering if I can do any thing to run E85? Do I need custom tune or can I use the tune I have loaded now? Main thing I don't want to lose and performance I have now with the 93 octane tune.....
Thanks
Richie

[Richiefcknrich]

Truck is a factory flex fuel truck.

[wehowardjr]

Yes you can.

[Richiefcknrich]

Yes to what part?

[wehowardjr]

This might answer your questions.

https://forum.diablosport.com//viewtopi ... 62&t=64486

[Richiefcknrich]

Thanks, but from what I read when I started searching is the 14-17 are different then 08-13. Something gm is doing different those newer year trucks. I more after the performance end, like is the e85 going to give me more power though the rpm range? I heard it adds a few hp high end but adds a good bit in the low to mid range rpm too. I have seen stuff googleing it but I want answers I can trust, that's why I am asking here. I figure you guys do this day in day out and would have the answers.
Thanks
Richie

[wehowardjr]

I would run E85 if I was living back in Illinois where E85 is cheaper than regular, or used to be 6 years ago. Here in central Florida where we now live E85 is more than gas and there are only a few stations that carry it. The cost and time to travel for a fill up just isn't worth it. The Diablo guys can help you more.

PEACE

[Richiefcknrich]

Thanks man I appreciate the help. I am in good old Michigan and we have e85 all over and is about $1.20 cheaper then the mobile 93 octane....... don't get me wrong saving cash is a plus but I am more looking to see if the performance is same or better then using 93 ........

[wehowardjr]

I just remembered I asked Lew about E85 and found his reply email to me. Not sure if it will help but will post it here anyway.

From me to Lew.....

Good morning. I contacted you not long ago about a custom tune and still plan to purchase one, soon I hope. But on to my question.... I currently have the 87 tune loaded on my 2011 Silverado with the 5.3. In a previous email you stated I would get better performance and I think mileage was mentioned if I do the 91 octane. Where I live the only “good” gas stations that sell 91 are about 3 to 5 miles away. With traffic at times I might as well pack a lunch driving that far. There is a station 5 minutes from me that sells E85. Is there a tune on the i2 that would give me better results over 87 and equal to 91 if I started using the E85?

Thanks in advance

Lew's reply....

nope.. there are no e85/flex fuel settings available in the tune file at all for that older 2011 truck.. only on 2014 and newer..


and e85 gives worse gas mileage anyway, due to the high alcohol content, and the stoich air fuel ratio of e85 is very rich at 9.0.. so you would lose a lot of mileage using e85...


you want to use 87/89 octane and the 87 tune, or use 91/93 octane and the Diablo Tune..

[Richiefcknrich]

Thanks man , looks like I might just have to keep with the 93 here..... that sucks was hoping to get a few more hp out of the e85.....

[06MonteSS]

you wouldn't gain much really anyway.. and you would lose mileage, since e85 has a different Air/Fuel Ratio, and makes it run a lot richer.. so you would lose mileage.. and you would have to fill up more often, so there's really no cost savings at all... e85 isn't really worth anything unless you go turbo/supercharger setup, bigger injectors, etc.. in which case you would need to take it to a shop to get a custom dyno tune anyway...

[Richiefcknrich]

Even if the truck uses the 30% more fuel at $1.20 per gallon here I would still save money per month, or am I missing something on the conversion of the fuel from 93 to e85?
You say I wouldn't gain much any way, does that mean I would have just as much or even a little more horse power with the e85 as I do on 93 octane?
You brought up e85 would help on a super charger on the truck, this winter I will be adding one and I heard you can run more then 7 lbs of boost with e85 (my understanding is max 7psi on pump 93 right)?
Thanks for the replys by the way I am just trying to figure it out ........