Ethanol blended gasoline, hurting engine performance, i'm afraid... Options

[saleeka]

This past weekend, I encountered a scenario that got me thinking about ethanol in gasoline again- is it hurting vehicle performance? It all started with a trip over to Wisconsin. On the way home, I had to fill the car up, so I pulled into a station just before I crossed back into MN. I've been filling my car up with premium fuel for quite some time, as I have always felt that it's made a difference in the performance of my car, even more so now that my car has 185,000 miles and has lost a lot of its original power. I noticed that the station I was at had premium fuel that was rated at 91 octane. Typically at home, the station I frequent sells 92, so immediately I thought to myself that I may notice a difference and experience decreased performance. I certainly did not expect it to make the difference that it did. There was a very noticeable improvement in the power that car was putting out! Now that I’ve used up half the tank and have seen that this wasn't a fluke, I started to ask myself why this particular tank of gas was making that difference, and it occurred to me just now.

Here in MN, it's been law for years that all gasoline sold in the state be at least 10% ethanol. After some research, I found that in WI, gasoline that is 91 octane or higher does not have this similar requirement. I then decided to read up on ethanol gasoline blends. I found that for ethanol blends to be used efficiently, the engine burning the blend should have higher fuel injection pressure or larger injectors than that of an engine that runs on gasoline alone, thus explaining why the ethanol-free gas in my car is "creating" more power... Annoying! This is also why only EFI engines can tolerate ethanol blended fuel without re-tuning of various parts of an engine's fuel supply system (cars without electronic oxygen sensors cannot compensate for the difference in energy the fuel contains. I'd also argue that some EFI systems, like our older ones, don't do a good job of adjusting, either. Most vehicles in the USA can only tolerate up to a 90/10 % split without big problems). More discouraging facts: ethanol blends have larger amounts of water in them compared to gasoline, and they also contribute to accelerated engine wear thanks to the "drying" effect alcohol has...

All this info makes me suspect that my car isn't as tired and worn out as I once thought. I'm now thinking it's the gas blends we are required to use in this state. For those of you who have easy access to ethanol-free gasoline, I'd strongly recommend selecting that choice over the blend.

[playr158]

you do know higher octane gas...the only difference between 91oct. and 87oct. is that 91oct. is HARDER to burn...thus less likey to give your little gt any performance.

[saleeka]

you do know higher octane gas...the only difference between 91oct. and 87oct. is that 91oct. is HARDER to burn...thus less likey to give your little gt any performance.

I think that this is an oversimplification because it doesn’t take into consideration the energy content of the fuel itself (something the octane rating doesn’t measure). Ethanol blend has less energy in comparison to regular gasoline, so having a higher octane rating makes the fuel more controllable, so to speak, and in turn you can extract more energy from that fuel. I haven't been able to compare "normal" gasoline in varying octane ratings to be able to agree or disagree with you, but when it comes to E10, I have noticed a power difference with different octane ratings, and in particular at higher RPMS. Throttle response with 87 rated E10 versus 91 rated "gasoline" is like comparing night and day...