LS4 Performance - 93 with ethanol or 91 without ethanol?

06-11-2012, 03:22 PM
I've heard some conflicting opinions about the adverse effects of ethanol so I wanted to ask you guys...

I'm currently tuned for 93 and I only buy from Sunoco. I just discovered a gas station selling 91 with no ethanol but it is a "Nice N Easy" convenient store and I'm not sure where their gas comes from. Would I be better off with running Sunoco 93 with ethanol or is the off brand 91 without ethanol a better option?

06-11-2012, 04:02 PM
i'd stick with the 93. the computer is going to be able to compensate for the it since its only going to be 10 or so percent ethanol.

also i dont think labeling if it contains ethanol is required in all sates now so they might both be ethanol.

06-11-2012, 05:08 PM
Damn! All the Northeast has 93 and 94 octane here. You need to move here

LS1 Racing
06-12-2012, 10:54 AM
Octane rating is simply a fuel's resistance to pre-ignition (knock). It doesn't really matter how they get there, ethanol or no, so 93 is 93 and 91 is 91, regardless of ethanol content. For our cars, always go with the highest octane rating, so I would use the 93.

Now, you will notice a hit to fuel mileage with ethanol, and the higher the percentage of ethanol, the worse the mileage gets.

You'll just have to decide what's best for you, but knowing how much these cars knock on the factory tune, I'd go with the 93.

06-12-2012, 01:58 PM
Yeah I thought I would be better off with 93 but some jackwagon was telling me different, and I didn't know for sure if I was right. Thanks for the responses.