E85 releases less thermal energy then 91 oct pump gas, when compared on a 1:1. At stoichiometric, E85 releases more thermal energy 91 oct, and it is this extra thermal energy that one must keep in mind when using it on engines with weak sleeves and ect. The engine runs cooler, but more energy is released out to the cylinder walls and ect. which can develop cracks in the cylinder sleeves that start within the cylinder and work their way up to the deck. (not from the top down)
Lower engine operating temps that come with using E85 increases charged air density, which allows for more fuel to be burned in the combustion process. After all, fire can't exist without a very important catalysts that fuels it, and that catalysts is oxygen. The fuels maximum thermal energy is released at the pinnacle of its thermal expansion process, which is initially set off by a spark set through ignition timing. !5 degrees advanced means the fuels thermal expansion process is timed to set off at 15 degrees before top dead center. The time it takes for a fuel to release it's max energy after igniting is called the burn rate. Ethanol burn rate is higher(burns faster) than 91oct. and increases it's burn rate faster then 91 oct. as cylinder temperatures rise.
Upgraded ignition systems are needed for the conversion and are needed for configurations using "coil on plug" at the 400hp+ mark on forced inducted engines. Our ignition of choice is the Jacob's Ignition Systems. If you can't find someone selling a good used one, then, Mallory Ignitions work the same.
DETONATION: Why and how it happens.
Temperatures rise in a combustion area from the heat that is generated by the simple compression of the air /fuel mixture. Pre-mature detonation of a fuel, before the combustion process is complete, is due to the fuel having reached it's flash point from that heat. (This is why over heated engines are known to diesel for a bit after being shut off) Detonation can destroy pistons, piston rings, rod bearings, and crack piston wrist pins. The damage to engine components is caused from the fuels maximum thermal energy being released while the piston is still in the compression stroke of the combustion process. It's like hitting the head of the piston with a sledge hammer while the piston is coming up.
There's too many beliefs on where to set ignition timing when tuning E85 and I don't want to waste my time arguing with someone else about their beliefs or style of tuning. Nothing can be argued with what I've posted in this so far, these are just facts.
Higher burn rate of ethanol means it's thermal expansion process needs to start later than that of 91oct. Engines that are found to take higher ignition timing settings after the E85 fuel conversion were initially not using a fuel with a proper octane rating for it's given application. (octane level is what raises the temperature of what the fuel flashes at)
City driving conditions are difficult to mimic during a tune session due to the higher engine compartment temperatures which cause heat soak. Tuning the engine at a minimum of 190F is recommended.
Discovery of stoichiometric reading from the first test in 2004 indicates what can be considered same for both 100% ethanol (E100) and petrol, meaning stoichiometric is the same for a mixture of 85% ethanol and 15% petrol (E85). It's good to be paranoid and taking away .1 a/f from the given, already known, stoichiometric of 14.7 a/f.
Power gains varied between forced inducted engine configurations. Power gains reflect better results with configurations lacking proper cooling of it's charged air.
Lower intake air temps as much as 120F on root style superchargers was noticed. All forced inducted configurations made substantial horsepower and torque gains. Naturally Aspirated engines made enough torque for considering the E85 conversion worth spending the time and money on.
Just trying to help some of you out there, that's all.
Pro Street Import
Dec. 15, 2021