@otis posted:I am in Canada and locally I have access to Petro Canada Ultra 94 with Ethanol and Shell V-Power 91 without. I haven't had problems with either, but am loyal to Shell and know of quite a few strong motors that don't have an issue on it. A couple years ago I was reading a few forums on which was better of the two. Of course there is lots written on the ethanol vs non and I came to find the story of a small time independent circle track racer (I can't remember if it was dirt track or pavement) that was in a class that couldn't run race fuel. He was quite competitive that year and was fighting for sponsorship. He said being an independent at the time and having to watch every dollar and make every race point count he had quite a few things broken down stat wise. In regards to fuel he said he was consistently getting a lap to a lap and a half more out of the Shell 91 vs the Petro Canada 94. He wouldn't have been pushing high horsepower in his class, but I thought it was an interesting statement.
It may have just been a reference that he acknowledges that higher octane fuel produces less heat calories and as a result less total horsepower?
I'm surprised that anyone would notice the differences between a 91 and a 94 octane fuel.
The advantage to say 108 Sunoco leaded racing gas is that you can run higher static compression ratio but in order to take advantage of that, you need to alter the distributor advance curve and probably the cam timing events. You would gain horsepower and torque by doing so but to go back to 91 unleaded pump gas you would have to reverse that.
So to say that you make more power with racing gas, it isn't the gas that makes more power, it's the other mechanical changes it allows you to make.
A street car that puts 5 gallons of 108 in at the track is only likely to see the engine idling down from 900 to 750 or so.
If you set up your engine with 10% ethanol gas then you have already made the adjustments to it. That amount of alcohol won't hurt anything in the engine. At 20% you are going to have problems with any rubber based components like fuel lines exposed to it.
You would need to read the engineering specs of the product that you want to use like an "Aeroquip) -6 fuel line to see if it is certified for alcohol exposure.