Originally Posted By: Cujet
Originally Posted By: 45ACP
Originally Posted By: Cujet
As a "turbo guy", I love E-85. It's cheap and it allows high compression engines to tolerate high boost and make excellent HP.
I do hope for continued E-85 pumps throughout the country.
It's not uncommon to use 11 to 1 compression ratio's on E-85, along with significant boost. Try that with 93 octane!
Im not following you. Im familiar with 87, 89, (90 and 91 in the Mid-west. 86 is NEVER going in my car) and 92, 93, 94 for Premium. I see 92 and 93 about equally.
I have also been taught that unless your car NEEDS it, get 87. I also do not know how to determine if a car NEEDS high octane gas, any car. Old or new...... import or domestic.. the 80s/90s/2000s on high-end cars (?) blur the line. 70s cars, too.
Now, about E85:
1. Doesnt it have special marked pumps, like Diesel does? (and therefore, select availability?)
2. How is it better than the 87, 89, 92/93?
Maybe i can learn something here.
Well, in this case, the fuel is unique and quite different from high octane gasolines. Also, the poster above is only partially correct. It's not just the mods that make the HP. It's the significantly increased volume of fuel required to achieve proper combustion (remember that alcohols contain less energy per gallon) . Put another way, it's because of its lower stoichiometric fuel ratio and lower heating value. This additional quantity of fuel, coupled with alcohol's excellent "latent heat of vaporization" result in a more dense air charge, whether normally aspirated (a modest improvement) or boosted (where it works exceptionally well in various ways such as cooling valves and pistons in addition to the more dense air).
There's more too. While the octane of E-85 is not all that high (94-96 in knock engine tests), it soundly outperforms much higher octane race gas in many forced induction applications. This is due to a situation where the fuel and air are quite densely packed in the combustion chamber, and certain fuels have vastly slower flame fronts and significantly higher detonation resistance under these conditions.
The two fuels that come to mind that work very well under very high boost applications are Toluene and certain alcohols. Both far exceed the predicted performance of the "calculated octane value". The 1980's vintage turbo F1 cars were a prime example of this (they ran off a mix of Toluene, that met modest octane rule requirements, yet were able to run unlimited boost!!! ) .
It's quite common for E85 turbo guys to run 11 to 1 compression ratio's and 30+++ pounds of boost in port fuel injected engines without any detonation detected. There are very few/none gasoline based fuels that can do this.
Yes, direct injected engines can run even higher CR's with E-85. Testing is now going on with turbocharged E85 only engines that run 14 to 1. It's almost difficult to believe, but it works very well and is quite thermally efficient.
I'm not sure this has been clarified in relation to 45ACP's question: E85 is 85% ethanol and 15% gasoline, not to be confused with the 85 OCTANE regular you'll see from eastern Colorado on up into the Rockies.
