[nick_casper]

I run 10% ethanol because it is what the car was tuned on. With 15% ethanol on the way will it be safe to run with the same tune? Would we be better off running ethanol free or E15 with an E10 tune?

[ZO6Ted]

Really depends on how aggressive the tune is and if your E tables are turned on. Tuners here can offer more.

[timesublime]

E15 is ~88 octane

[KingLT1]

No unless a flex sensor is installed and the tune is set up for it. Then yes up to the point where you run out of fuel system. If stock fuel system is still in place then back to No because stock fueling is barely adequate for E10 with boost.

[KingLT1]

Originally Posted by timesublime

E15 is ~88 octane

Not if it's 93 octane blended with 15% Ethanol.

[timesublime]

E15, often sold at the pump as Unleaded 88, for its octane rating, can safely be used in all cars, trucks and SUVs from 2001 on.

[nick_casper]

The E10 here is available in 91 octane. Hopefully we can still get E10 through the summer.

[mariojas]

Originally Posted by nick_casper

The E10 here is available in 91 octane. What are you all going to use if E15 is all that is available after Bidens executive order.

[KingLT1]

Originally Posted by timesublime

E15, often sold at the pump as Unleaded 88, for its octane rating, can safely be used in all cars, trucks and SUVs from 2001 on.

That's because it's mixed with low octane pump fuel. I agree not to use pump E15 If it's labeled 88 octane. Ethanol basically adds octane to the base fuel it's being blended with.

[cjperformance]

Originally Posted by nick_casper

I run 10% ethanol because it is what the car was tuned on. With 15% ethanol on the way will it be safe to run with the same tune? Would we be better off running ethanol free or E15 with an E10 tune?

Depends on your tune.

#1 The octane would still have to meet or exceed what's recommended... for a supercharger running any real boost, I would think anything less than 91 octane is "bad". Even 93 is "bad", lol.

#2 Even if the octane is right... an extra 5% eth in E15 is going to make it run slightly leaner than E10.

Bottom line, run what the tune is designed for, if you have flex fuel and the octane is sufficient, then you should be ok.

If the octane is too low it's asking for trouble.

If the octane is ok, but you dont have a flex fuel tune... then it's going to run a little leaner, which is especially bad for a sc. Enough to cause problems? Don't know, depends on your setup.

With no flex fuel, the eth free is prob better because it will tend to run richer. It's counter-intuitive because it will run richer, but consume less volume of fuel.

[timesublime]

Re-reading the mandate, and from what I gather it only applies to e15-88 octane. The mandate allows it to be sold in the summertime in locations that typically disallow e15 in the summer months. Nothing in there about blending other grades to 15%.

[nick_casper]

Originally Posted by timesublime

Re-reading the mandate, and from what I gather it only applies to e15-88 octane. The mandate allows it to be sold in the summertime in locations that typically disallow e15 in the summer months. Nothing in there about blending other grades to 15%.

I hope this is the way it goes. I work in the O&G industry and we are hearing rumblings of major fuel shortages this summer. I think I'll use eth free over E15 if those are my only choices.