How much boost?

mine was tuned at 18.5psi on pump gas 93. I don't think its the amount of boost alone that matters, its the amount of timing and boost that determines the octane you need.
 
I've been looking into this also. not really to try to run more boost, just a cheaper fuel. Mine is mostly stock, no cats late model blower, a little od, 73mm maf, 190 lph fuel pump and 36lb injectors. i've got a tweecer to take care of the tweeking. From what i gathered, the ignition curve is different from e85 vs 93 and also the afr must be modified. It looks like the closed loop should be ok. since the o2 sensor will account for the increased need for fuel, as long as you don't reach the limits of the injectors. how is the open loop afr value derived? it was stated that stoich is 1 volt for both fuels. http://www.e85mustangs.com/tuning.html It looks like e85 requires about 30% more fuel, so do the injectors need to be 30% bigger as a starting point? after the fuel system is upgraded, is all that is need is to tune for the afr with a wideband? Also i was under the impression that if your vehicle was designed to accept 10 and 15% blended gasoline that the fuel system should be compatable with e85.
sorry so long
 
First off, don't attempt to use the software that comes with that Tweecer... 3/4's of the parameters are wrong for our cars.

Its not so much that you require more boost, its you can run more boost with E85 if you wanted to. You do need to increase fuel delivery as was mentioned.

As for Stoic, it hovers around the .46 volt range on the narrowbands, but the car doesn't sit there to get stoic, it actually keeps adjusting your AFR from rich to lean around stoic so you'll see the O2 sensor voltage bounce back n forth around the .46 range.

A Wideband is a must to tune for E85.

Frit
 
I've been looking into this also. not really to try to run more boost, just a cheaper fuel. Mine is mostly stock, no cats late model blower, a little od, 73mm maf, 190 lph fuel pump and 36lb injectors. i've got a tweecer to take care of the tweeking. From what i gathered, the ignition curve is different from e85 vs 93 and also the afr must be modified.

Stoic is different on alcohol compared with gasoline, so yes the AFR's will have to be different.


It looks like the closed loop should be ok. since the o2 sensor will account for the increased need for fuel, as long as you don't reach the limits of the injectors. how is the open loop afr value derived?

Open loop fueling is probably derived from the open loop fueling maps.

it was stated that stoich is 1 volt for both fuels.

Take this for what it's worth. Don't tune your car off a narrowband sensor. Wideband sensors are not expensive.


http://www.e85mustangs.com/tuning.html It looks like e85 requires about 30% more fuel, so do the injectors need to be 30% bigger as a starting point? after the fuel system is upgraded, is all that is need is to tune for the afr with a wideband? Also i was under the impression that if your vehicle was designed to accept 10 and 15% blended gasoline that the fuel system should be compatable with e85.
sorry so long

You will need larger injectors if you're at or above 70% duty cycle at wide open throttle then, but as a simple answer, yes you will need bigger injectors.

As for tuning. You can run a lot more timing and a lot more boost on E-85 in comparison to gasoline. Alcohol has better resistance to detonation.
 
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