Every now and then I arrive at the pumps and find the there is no E5, I have an S&S carb 105 cui Evo motor so E10 is a no go area.. apart from the terrible pinking it causes, I think there are other corrosion issues associated with it.
So is the solution to carry around a bottle of fuel additive or octane booster? Just for emergency use.. or perhaps just use E10 and an additive permanently.
Had an excellent response from @Alex Henderson elsewhere but want to add it here to help other members..
Alex Henderson
You need your jetting and/or timing looking at if your engine won't run without pinking on E10. It doesn't matter who manufactures the engine, what displacement it is or whether it's carbed or injected. Pinking/detonation occurs when the cranking pressure is too high for the octane rating of the fuel and/or the ignition point (timing) is too advanced. A 105" engine can easily have a cranking pressure lower than an 80" engine - this depends on the intake closing point of the camshaft. I run a carbed 11.5:1 engine but it only cranks 195 psi and runs perfectly on E10. I'm finding that I can advance the timing more with E10 fuel which would suggest that it increases the octane rating. It also burns cooler and is cleaner in terms of piston crown deposits - all good. It is corrosive to some alloys and it embrittles Nitrile o-rings which is not really a problem - just change any exposed o-rings to Viton. I was concerned initially because a lot of my builds crank well over 200 psi but I'm seeing no issues. E10 contains less energy by volume than non ethanol fuel which means that running E10 in an engine without any air/fuel ratio corrections will run richer and this is why there are reports of worse mileage. I'm at the dyno regularly with engines running E10 and we're seeing no loss of power once they're set up correctly. The last one was a 117" build at 205 psi and it put out 137 ft/lbs of torque. I have no problems with it.
The Australians have E85 and use the greater knock resistance to get improved performance from turbo cars. The sophisticated aftermarket ECUs are able to take the output from a "flex fuel sensor" and adjust ignition timing and boost depending on what's in the tank.
