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Discussion Starter · #1 ·
Hi,

I was curious if anyone here has converted to E85 by using 30% or similar larger injectors than stock and no change to the base tune? I stumbled across the idea and it turns out that others have tried it and it works well.


E85 is attractive in a boosted application. It is much more detonation resistant and runs cooler. That's the point.
 

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Just because you put a larger injector in and give it e85 the ECU will not know that it needs 30% more fuel, it will need to be tuned. And depending on what year your truck is, "just getting it tuned" isn't an option.
 

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Discussion Starter · #3 ·
Just because you put a larger injector in and give it e85 the ECU will not know that it needs 30% more fuel, it will need to be tuned. And depending on what year your truck is, "just getting it tuned" isn't an option.
The computer knows lamba, which On E85 is approximately 30% more fuel than gasoline. So lamba will be possible on E85 at the same injector pulse width as the 30% smaller injectors.

When they tune for E85 on a stock injector they raise the fueling 30% across the curve as a base tune.

They are doing the methods I described on other vendors with success. It gets it really close and during closed loop about dead center.

To do it right you'd change the injectors, empty the fuel system of gasoline then fill it with e85. The first startup after the larger injectors will be with E85 in the system.
 

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The computer knows lamba, which On E85 is approximately 30% more fuel than gasoline. So lamba will be possible on E85 at the same injector pulse width as the 30% smaller injectors.

When they tune for E85 on a stock injector they raise the fueling 30% across the curve as a base tune.

They are doing the methods I described on other vendors with success. It gets it really close and during closed loop about dead center.

To do it right you'd change the injectors, empty the fuel system of gasoline then fill it with e85. The first startup after the larger injectors will be with E85 in the system.
I've been on this forum since 2008, and never read about anyone doing what you're describing. You should be a pioneer and let us know. lol
 

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Discussion Starter · #5 ·
I've been on this forum since 2008, and never read about anyone doing what you're describing. You should be a pioneer and let us know. lol
Ok. They are doing it on this thread, it's on the LS platform, but there are other platforms who also used this shortcut. On cars that they tune the ECU's the first step is usually to bump fuel by 30% across the board. This gets closed loop very close, and WOT will "work", but can use further tuning to optimize it. Here is the thread: Running E85 with out Tuning?? - LS1TECH - Camaro and Firebird Forum Discussion
 

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I think it will work. The computer doesn't care about anything other than making 14.7:1 AFR. It simply adjusts injector pulse widths until its sensors read that it's made Lambda. Stock injectors can't deliver enough, but bigger injectors can.
But, why would you want to? The fuel efficiency would go through the floor. What you might save at the pump you will more than make up for in increased fuel usage. E-85 has nowhere near the energy density of regular. You will use about 25%-30% more fuel.
 
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Discussion Starter · #7 ·
I think it will work. The computer doesn't care about anything other than making 14.7:1 AFR. It simply adjusts injector pulse widths until its sensors read that it's made Lambda. Stock injectors can't deliver enough, but bigger injectors can.
But, why would you want to? The fuel efficiency would go through the floor. What you might save at the pump you will more than make up for in increased fuel usage. E-85 has nowhere near the energy density of regular. You will use about 25%-30% more fuel.
O2's measure oxygen content or lambda. On E85 it's 9.765:1. The reason for doing it is E85 runs cooler, it's 35% cheaper than the 93 octane here in my area, it will be extremely hard to almost impossible to detonate at the BOOST levels i intend to run, and it simplifies the system because you don't need timing retard on E85 at the boost levels I will be at. E85 will give me additional comfort under boost.

Fuel ........................ AFRst ........ FARst ....... Equivalence Ratio ... Lambda
Gas stoich ................ 14.7 .......... 0.068 ................ 1 ................... 1
Gas max power rich .... 12.5 .......... 0.08 ................. 1.176 .............. 0.8503
Gas max power lean .... 13.23 ........ 0.0755 .............. 1.111 ............. 0.900
E85 stoich .................. 9.765 ....... 0.10235 ............ 1 ................... 1
E85 max power rich ...... 6.975 ....... 0.1434 .............. 1.40 ............... 0.7143
E85 max power lean ..... 8.4687 ...... 0.118 ............... 1.153 .............. 0.8673
E100 stoich ................ 9.0078 ...... 0.111 ............... 1 .................... 1
E100 max power rich .... 6.429 ........ 0.155 .............. 1.4 .................. 0.714
E100 max power lean .... 7.8 .... ...... 0.128 .............. 1.15 ................ 0.870
 
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