Here is a prime example of a returning E-tune customer that first tuned on pump gas and is now ready to do a second tune on E85 fuel.

This particular car has no flex fuel sensor so we can not truly consider this a “flex fuel” tune but the owner has easy access to E85 so he has no need to blend the E85/gasoline.

This E85 tune, like the original tune is all done through a series of emails and the occasional live connection when needed. Through a series of customer provided data logs and tuner provided tune/calibration revisions the engine is finally tuned for the best possible balance of reliability and performance.

Honda S2000 2.4L stroker Infinity ECU upgrade

Before diving into the calibration it is very important to ensure your fuel system and ECU are up to the task of making the switch to E85. Here is a short list of just a few common E85 related parts we use on all of our shop cars and customer builds.

If you are planning to make the switch to E85 don’t hesitate to contact us for questions support and the best possible pricing on all your hardware needs.

Supporting mods for E85:

  1. Ethanol safe fuel pumps – Walbro, AEM and Bosch fuel pumps
  2. Injector Dynamics 1300cc ID1300x fuel injectors                                                   ​
  3. Flex Fuel friendly ECU or EMS – AEM Infinity & Motec M1ecu
  4. Adjustable fuel pressure regulator- AEM,  Radium Engineering
  5. Custom Tune or E-tune – Brewed AEM Infinity E-tune
  6. Wide band o2 gauge/sensor – X Series AFR gauge & sensor kit
  7. Fuel pressure sensor and or gauge – X Series 0-100 psi pressure gauge

Pump gas tune data log Series 2 AEM EMS S2000 2.4L stroker

AEM E-tune S2000 e85
AEM E-tune S2000 e85

Modifying the pump gas tune for E85 (Fuel & AFR/Lambda)

With the pump gas map completed ready for E85 we start by modifying the main fuel map/s (either the main map or if flex fuel a secondary/flex fuel map).

**note you may also want to modify your Lambda/AFR targets** An engine will require ~10-35% more fuel throughout the rpm range with E85 vs gasoline.

One benefit to Ethanol rich fuels is that it will burn/ignite/combust at leaner AFR than gasoline. This allows the tuner to “lean burn” (1.1-1.3 Lambda) the engine at low RPM and engine load saving fuel and in some cases drastically reducing emissions.

Of course, under mid to high engine load and RPM the AFR must be on the “rich” side of things (.7-.9 Lambda depending on engine power/size and use).

Modifying the pump gas tune for E85 (Ignition timing)

Moving onto the ignition timing portion of the E85 calibration we can make a general increase of 1-2* timing across the entire map and in some case up to ~9* on some engines.

In most cases a NA high compression engine like the stroked F20 in the examples will take 2-7* more timing throughout the entire RPM range. At higher RPM the timing advance will increase slightly more due to the burn characteristics of Ethanol rich fuel.

**tuning the ignition timing portion of the map will make power but if pushed too far can easily damage the engine. It is very important to leave this type of tuning to a professional unless your are 100% confident in tuning theory and the software/ECU being used.**

E85 Fuel & Timing map Series 2 AEM EMS S2000 2.4L stroker

**Note, this example is WILL NOT work perfectly for your engine, do not attempt to simply copy these values into your calibration. To be used as an example and reference point only, no 2 engines, fuels or setups are exactly the same, tune accordingly!**

AEM E-tune S2000 e85 retune

Tuning tip:

Knock – a frequency, sound, vibration from an internal combustion engine, often used to describe pre ignition or detonation Check out the Velocity Element Knock Kits with complete shielded coax harness.

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