2006 GMC Sierra 5.3 Flex Fuel/E85?

[airitech]

Hey guys! I've been wanting to run E85 for awhile just to see how it is and i have a few questions.

Trucks a 2006 gmc sierra 1500 5.3 vortec crew cab.

I also heard like this year has an aluminum block or something.

 

Yes my VIN has the Z in the 8th digit, and the gas cap says Flex Fuel E85. I was wondering what the "rules" so to speak are with E85. Can i run 100% E85 or is there a limit like 50% gas and 50% ethanol? Can i just goto the pump having a half a tank of normal 87 octane and fill the rest up with E85 and be fine, or do i have to get my ECU reporgrammed?

 

Basically looking to ask if i can goto the E85 pump in town, and fill up even if i have any amount of normal 87 octane in.

 

I know to expect fuel mileage drops, but do i get a horsepower increase?

 

Thanks in advance!

[wehowardjr]

I asked a knowledgeable person about running E-85 in my 2011 Silverado and his answer was as follows.... "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..."

 

I'm sure it has it's fans but from what this guy said I plan to stay away from it.

[Batiatus]

I run E85 almost exclusively in my 5.3. Yes, the mileage drops from 11.5 MPG to about 9.8 MPG. The cost difference at the pump is 31¢, so the cost to run E85 vs gas is negligible for me. I like the performance & lower emissions of the E85.

 

YMMV, literally.

[kstruckcountry]

The Flex Fuel GMT800 pickups have an iron block, if you pop the hood it's easy to spot. The pickup should run more consistently if you get the tank down to the empty light before putting in E85. The stock tune is pretty lazy on these pickups, so the power bump on E85 may not be all that noticeable without a custom tune. Decreased mpg and cold start will be noticed on E85.

 

Sent from my SM-G920V using Tapatalk