E85 blend

[grainboy]

I have a flex fuel 5.3 in my gmc pickup. At 10:1, it sometimes pings on straight gasoline. Yesterday I added 7 gallons of E85 to the tank, then topped off with gas, for total of 25 gallons. No pinging, and no loss of power either. My truck doesnt run well on straight E85 in the summers in Arizona.

My question is: How much E85 can I blend with gas in a normal carburated system without damage to fuel system? Bear in mind most of Phoenix gas is E10 year round. 25% E85?

 

[pyroman]

Someone may have to back me up on this but I wouldn't go above E15. At that point, damage to your fuel system is very likely.

 

[blown65]

Takes a different tune. More E the more fuel your going to need. Personally after all the small engine damage that happened here locally, Ill never run ethanol fuels if I can help it. Luckily we have a few stations that have non-E fuels.

Every small engine that we own ended up with stuck intake valves and bent pushrods.

 

[downwardspiral]

Ethanol has a different stoichiometric AFR than fuel, and different ratios of ethanol to gasoline require different tunes (as mentioned). A carbureter can be tuned a run a certain ratio. As mentioned, the ethanol will eat away at the fuel system, so if you want to run e85 you can build an e85 safe fuel system.To really run e85 as a flex fuel, you need a fuel composition sensor to compensate for what is actually entering the engine from moment to moment. This really isn't possible with a carburetor, but possible with efi (megasquirt can handle it ).

 

[grainboy]

All I wanted to do is raise the octane on the cheap. Tolulene is an option, but is smelly and toxic. I have a readily available supply of E85, and am going to blend in one gallon to a tank and see what happens.

 

[downwardspiral]

All I wanted to do is raise the octane on the cheap. Tolulene is an option, but is smelly and toxic. I have a readily available supply of E85, and am going to blend in one gallon to a tank and see what happens.

I wouldn't personally do it. If you decide to give it a shot post back with how it runs. I'm curious to see what would happen. . I've heard nothing but complaints about higer levels ethanol with carburetors on stock tunes. e85 does smell pretty nice .