|Thought I should share this from Greg at SZ after he helped me out wondering the same stuff this week. I've been asking a lot of the same questions. Also, it might save him from repeating himself with others.
You can run the stock ECU with our map switcher and programs to run any amount of Ethanol safely.
You will need to read the ethanol content to know what program to select.
For up to 550 HP, the fuel requirement would be 740cc injectors and a Walbro 525 fuel pump, the OEM Nissan hose works best, no issues with the factory fuel rails.
Here is more detail……
E85 is designed as a flex fuel, it is not safe to run as a single program for any ethanol content.
E85 assumes 85% ethanol and 15% gas, but It is not.
E85 is legal to sell as low as 51% and as high as 85%. The fuel volume required for the proper mixture changes as the ethanol content changes.
I have never seen 85% come out of pump.
Here in California, our E85 has been 80% year round.
Many cold areas of the Country sell 65% in the cold months, and 70 to 80% in the summer and varies between stations and areas.
You can also get stuck not finding a E85 station and require putting in pump fuel, so you really want the ability to put any amount of E85 or pump fuel safely. It is difficult to change fuels with E85 and run a single E85 tune, the burn rate is crazy different than normal fuel.
Ethanol and gas can be mixed in any amount, the more ethanol content, the more boost you can run, and the more ignition timing you can run safely.
The more ethanol content, the more fuel is required to have the correct mixture.
E85 is not always the same, you can get stuck with some E85, need to buy more fuel and only be able to get pump gas, so you fill up and now you have say E25 or E30, you cannot run your pump gas tune because it would be too lean, you cannot run your E80 tune because it would be too rich and will have too much timing.
We make tune scaling for different ethanol contents for the stock ECU, it requires manually selecting based on what the ethanol content gauge reads. To make it simple, we provide tunes for every 10% with our map selector , you just need a gauge and sensor to know what you have, and match the tune.
To keep it simple, we make corresponding number tunes.
0 = no start program
1 = E10 (pump fuel is E10, 90% gas with 10% ethanol)
2 = E20
3 = E30
4 = E40
5 = E50
6 = E60
7 = E70
8 = E80 (this would be safe for full E85)
This way you have a tune for whatever you get at the pump, or if you cannot get E85. You can mix any amount of pump gas with E85 and you will have a proper tune.
You would want to install an ethanol content sensor and gauge, we have a plug and play unit that only requires adding power and ground, and installing the ethanol sensor in line on the fuel return hose.
You can view the parts here:
Ethanol sensor and gauge
The switcher set up runs $350, the 8 programs to run E85 runs $350
Full E85 requires 30% more fuel than gasoline at full load, you can run it leaner at cruise, we also can run a lot more timing, so at cruise E85 consumes about 15 to 20% more fuel than gasoline.
Still a great value over race fuel for the cooling effect and high octane.
So to run E85 at full tilt, the injectors need to be 30% larger than gasoline, more fuel pump capacity is also required.
The 740cc injectors support 750 wheel HP on gasoline, and about 550 wheel HP on E85. For higher power E85 cars we run top feed injectors.
The stock fuel pump supports 550 to 600 wheel HP on Gasoline, about 380 to 420 wheel HP on E85.
The Walboro 525 fuel pump supports at least 750 wheel HP on E85.