Quote:
Originally Posted by VNeBLOB42
I knew I could count on you. walloftext. maybe one day you can show us noobs how to do it.  |
Challenge accepted, this is a non-techie wall of text back at you:
Other port-injected markets swap injectors to inject the massive amount of fuel required to support higher HP with typically pure e85, compared to stock gasoline requirements. It's never done, to my knowledge, for the sake of material issues with e85. In fact, I just plain haven't seen diddly to support e85's corrosive-witchcraft with ANY late model vehicle. I am fairly confident that the n54 market will enjoy 100% e85 tuning via cobb in the next year. Piggies cannot support such a thing without taking some leaps of faith, but I digress.
e85 will do nothing for you on a stock tune except restore power lost due to excessive timing being pulled. Same goes for any tune - e85 simply and purely raises the knock threshold. You can run more timing, more boost, and make more power before running into knock ('bad' timing corrections - the stock tune makes a living correcting timing even on good 93 octane).
The N54 DME allows for 34% more fuel to be added to the original amount it expects to inject for gasoline for a certain load/rpm/afr. Basically, you need more e85 per unit of air mixture than gasoline to hit stoich, so the DME adds e85 by upping STFT% realtime, fully closed loop, to hit AFR targets. It says "woah wtf this mix is running LEAN add fuel, add fuel, add fuel, ok it's close, add some more, ok now we're good." Make sense? LTFT learns this for idle and cruise, STFT deals exclusively with this issue during WOT.
Go over 34% STFT, and you will run lean because the DME has no further authority to inject more fuel. You will pop mixture codes with a CEL. I hit this ceiling at 45% e85.
Bottom line: Piggies have some maps that take advantage of the higher knock threshold of e85 mixes. They either run more boost, more timing, leaner AFR, or all three. ATR is a sandbox and suffice to say the same is true, everything can be made more "aggressive" to find power under this higher knock threshold. Stock tunes will recover lost power due to timing corrections being reduced. Most stay around 20-40% mixed, almost noone does more than 50% right now due to inherent DME limitations, namely STFT at WOT.