Thread: E85

**Razer440** · 03-15-2011, 01:52 AM

I'm sure it has been discussed on here before. But E85 in out cars. Is it okay to run some E 85 in a 3S or is it better to stick with gasoline? I am just curious cause there is a gas station near me that sells E 85 ($2.99/gal) and Premium gas is $3.85 /gal.
Can I save some money and use E85?

**beepbeep** · 03-15-2011, 09:58 AM

There are modifications that need to be done to your 3S before you can start using E85, as in fuel pump, fuel injectors and fuel controller.. You can't just put it in the tank in place of your normal gasoline and go. So, you will have to consider the cost of the modifications into account as well as the difference per gallon of fuel. HTH

**Ninja Performance** · 03-15-2011, 10:27 AM

Plus the added 30-40% volume of fuel you will use off sets the savings.

-Chris

**Tiberius** · 03-15-2011, 10:27 AM

I think from a mechanics point of view E85 is OK in our cars. I read somewhere you should change the injector seals to Viton but that's about it.
But you can't switch to E85 without changing the engine management and you need to change to higher capacity injectors and fuel pump.

**Ninja Performance** · 03-15-2011, 10:31 AM

If you increase your injectors to ones that flow 30-35% more, then you may get away without having a fuel controller. But 30-35 is an estimate and E85 isn't always E85 so... It's not the way to do it.

-Chris

**Jesters Deadd** · 03-25-2011, 03:55 PM

Plus you will have closed loop issues if you don't do something with the o2 sensors.

**Tiberius** · 03-25-2011, 04:14 PM

If the fuel ratio has been adjusted there won't be any closed loop problems. O2 voltage for stoich mixture is the same for E85 as for petrol, only the AFR it represents is different.
So adjust the AFR with bigger injectors and an S-AFC and you're good to go.

**Jesters Deadd** · 03-29-2011, 06:06 PM

The AFR for gas is 14.7ish and E85 is 9.8ish... how will his O2s give the same voltages if he uses the original O2s?
If he put new injectors in and adjusts his S-AFC to get the correct 9.8 AFR, when the car goes closed loop it will always think it is running rich and try to lean it out. O2s don't read when the fuel is at stoich they read AFRs. 14.7 AFR for E85 is really lean. His trims will all bottom out and the closed loop function will be pointless. It will actually keep messing up your "tune" until the trims all bottom out.

**Tiberius** · 03-29-2011, 06:15 PM

because O2 sensors don't measure AFR, they measure oxygen in the exhaust gas. An O2 voltage of 0.5 V means the same amount of oxygen in the exhaust gas with E85 as with normal petrol.
A (not adjustable) AFR gauge scales the O2 voltage to an AFR by relating the voltage to a scale for petrol combustion. Strike 14.7 on the gauge face and put 9.8 in it's place and your gauge is corrected for E85.