Everything needed for E85

[Darbshaw]

I am going to be needing a new fuel pump and I am planning on getting the radium engineering kit as a replacement for the OEM (SC plans in the future). I was gonna be going with the Walboro 255 but I saw the AEM pump for E85 is only an extra $25. http://www.radiumauto.com/Fuel-Pump-...6-M3-P314.aspx

My question is: Can I run e85 with just this upgraded pump? Would I need the extra fuel commander thing sold on like build journal or is that just needed to run less than E85, E60 etc. This may also be a dumb question but I would also be able to run normal 93 octane on the e85 pump or strictly e85
https://thebuildjournal.com/shop/bmw...el-kit-e46-m3/

Thanks for any help on the noobish questions

[mrgizmo04]

You don't NEED a special fuel pump to run e85 and the fuel pump on it's own is not what is going to make you power. So...

Yes, you do need either an e85 specific tune (at which point you will need to run the same ethanol content all the time, because the tune is "static" and is tuned for specific ethanol content, however gas stations with e85 and not all created equal and actual ethanol content varies), or, a piggy back commander like APE or AFD. These commanders have a sensor that figures out % ethanol running through the lines and adjusts the injector duty cycle (since ethanol has less energy density, duty cycles are increased). With a commander you can flip flop all you want between different mixes of 91/93 and "e85" from the stations and it will adjust the duty cycle automatically. And those commander kits come with all the electrical connectors and fuel lines that you need.

If you have a lot of other mods like headers, intake, cams, tune, etc, you need to look into upgrading your injectors because stock ones will be beyond maxed out.

Sent from my SM-G950U using Tapatalk

[Tbonem3]

If you have a lot of other mods like headers, intake, cams, tune, etc, you need to look into upgrading your injectors because stock ones will be beyond maxed out.

Would you say that even if you always targeted around an E50 mix?

[mrgizmo04]

Would you say that even if you always targeted around an E50 mix?

Relationship between mods and e85 is non linear and inverse, the more mods you have the lower the "e" you can run on stock injectors. On a stock engine with an e85 kit, you can prob run full e85 and be safe. Think of the other extreme case if you ran a supercharger on stock injectors. That thing pumps in so much air that stock injectors have to be at 100+% duty cycle to keep up just on pump gas, so running any e85 will further overload them and in that case you should be running e0 since they are already maxed out.

Somewhere between fully stock (injectors can handle full e85) and full blown (injectors can handle no more additional fueling and thus can handle e0), lies the combination of all the NA mods with exhausts/intakes/cams/tunes. What that exact spectrum from e85 to e0 corresponding to NA mods is, I dont know, but i think from what I read and discussed with Hassan, doing full exhaust, non-csl intake and a tune pushes you toward E50 for semi safe target. Further adding csl rep box and cams on top I'd assume would probably warrant E30 max before injectors are fully overloaded (picking a number out thin air with no science behind it here, just to illustrate a point).

Sent from my SM-G950U using Tapatalk

[mrgizmo04]

Supercharger as example in the above was just as an easy extreme case to illustrate a point, realistically you will hit over 100% injector duty cycle with combinations of mods even before going forced induction.

Sent from my SM-G950U using Tapatalk

[Darbshaw]

Okay, thanks for the help. I forgot to add but I currently have a Build Journal B-Spec tune for 93/E85, catless headers, and an Agency Power Section 3. So nothing too crazy. I do plan on doing my injectors as well eventually. Although the SC kits I'm looking at come with high flow injectors with them so I'm debating the need of buying new ones now or not.

I'd like to just get my current ones cleaned but I don't think I can lose the car for roughly a week to do so. My car is currently at 163k and from what I've know its the same fuel pump and injectors since she left the factory.

[Jimbo's M]

For myself with stock DME, I see no reason to go above the lower E60's just for the simple fact that that is ~100 octane and no further gains can be had and will merely tax the duty cycle/fuel pump unnecessarily.

[Nihilation]

From what I understand, a stock'ish engine will nearly max out the duty cycle on stock injectors when running 100% E85. Especially so with mods and a tune. A safer ethanol blend would be in the E50-60 range, which from what I hear is about the sweet spot.

My pure E85 setup sitting the corner is:

1. AEM 320lph pump (installed)
2. Bosch EV14 52lb 550cc fuel injectors (in hand)
3. APE x85 flex fuel kit (in hand)
4. 93 Octane Tune from HTE (or your favorite tuner)

This setup will allow my car to run 100% E85 or any 93 octane mix however since the tune would be for 93 octane the advantages of E85 are limited to:

1. Cheaper fuel, at the expense of decreased (30% or so) fuel economy
2. Safer on the engine because
   1. Richer air-fuel ratio burns cooler
   2. More knock resistant
      1. May allow for a more aggressive 93 octane tune

To maximize power output with E85 you'll need a e-blend specific tune that can increase timing over what 93 octane can handle -- but on our NA engines, we're probably only talking 5-10 whp if we're lucky. So is it worth it? Maybe if you have the ability to easily switch maps (MSS Mapper or a stand alone ECU?) at the pump. For me, I simply want to try E85 for myself and know that I can run it if I choose to.