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SMT-FTX Technical Manual - Ethanol

SMT-FTX TECHNICAL MANUAL

Perfect Power Online Manuals.

 

Support for your SMT-FTX Unit.

ETHANOL

The addition of Ethanol to the regular fuel, or using E85 (15% fuel, 85% Ethanol) requires some special considerations:

 

  • You need approx. 30% more fuel quantity for E85
  • The Octane rating of E85 is off the chart (very high)
  • It is green
  • It has cold start problems


The Ethanol applications can be described in three main categories:

 

  • Ethanol Performance
  • Manual Ethanol adjustment
  • Automatic Ethanol adjustment

 

 

ETHANOL COLD START

 

The SMT-FTX has a COLD START enrichment table linked to the engine temperature. Ethanol requires very large fuel quantities below zero Celsius.

 

These large fuel quantities work in two ways:

  • They increase compression (which results in some heat)
  • They increase the ‘CARBON’ fuel portion for ignition

 

The E85 Cold start map is only active in Manual and automatic Ethanol mode.
The supplied DEFAULT map is a good start. Entry is in percent!

 

 

ETHANOL FOR PERFORMANCE

 

In this application one would use the very high Octane rating together with high compression and improved ignition. Of course, you need to put 30% more fuel in to the engine and need to check if the OEM injector’s can handle this. Remember, if you increase the power you need more fuel as well. The required fuel gets easily out of hand as can been seen:


20% more power
30% more fuel for E85
=56% total fuel increase


This increase is in most cases, if not all, too much for the standard injectors to handle. In most cases even the fuel pump can’t handle this.

 

The first solution which comes to mind is replacing the injectors with higher flow rate ones. However, this is not ideal because the side effects are numerous. A better solution is to use an EXTRA INJECTOR (AUXILIARY INJECTOR) placed in the manifold. If this extra injector is of the same flow rare as the OEM injector then it can increase the fuel delivery by 25% for a four cylinder engine. Double the flow rate and you have a solution!

 

The mechanical work is easy as compared to replacing the OEM injectors with high flow rate ones.
Regardless of the previous advice here is a list of possible solutions to a fuel increase of 50%


BIGGER INJECTORS
The SMT-FTX can reduce the injection time by up to 80%


INCREASE FUEL PRESSURE PROGRESSIVELY
It is a little tricky to find the correct fuel pressure regulator, but it can work by using the increase/decrease OEM fuel injection.


AUXILIARY INJECTION AND MECHANICAL WORK
It makes use of the injector staging or normal injection mapping of the AUXILIARY injector circuit.


A LITTLE BIT OF EVERYTHING
The SMT-FTX is your partner. The solution above depends very much on your circumstances and what you are used to.

 

 

ETHANOL FOR STREET USE, MANUAL ADJUST

 

This is the most popular version, because fantastic fuel economy can be achieved. Here is how it works:
The tanking if E85 requires that you add fuel on top of the normal fuel injection.
The question is how much? The actual fuel required by the engine depends
very much on your driving and what you expect your engine to do.

For the following table I assume that you have undiluted E85 in your tank:

 

Operation Addition Save
Cold starting 33% 0
Heavy Towing 33% 0
Town driving 22% 9%
Cruising 15% 16%

 

The above table is a guideline! More or less savings can be expected.
If you race the engine from one traffic light to the next then you probable save less than 9%.

To enter this operation:
Tick        SYSTEM DEF, Man E85: AN1 is Mix

SMT-FTX Fuel Tuner - ShiftF2 - System Definition

The next step requires some engineering:
Connect the wiper of a potentiometer to the AN1IN pin 2.

 

SMT-FTX Fuel Tuner - Potentiometer Wiring

Connect power (+5V) to the potentiometer.

The following drawing explains:

SMT-FTX Fuel Tuner - ShiftF2 - System Definition

Explanations: Putting close to 5V on the AN1IN input pin causes the unit to add 33% more fuel and it will activate the COLD START enrichment.

 

 

ETHANOL FOR STREET USE, AUTOMATIC ADJUST

 

This mode of operation requires that the unit has a NARROW BAND AFR PROBE. The units will then monitor the AFR measured, compare it with the AFR Target and adjust the Ethanol fuel addition once the measured AFR falls outside the window.

 

Setting up:
Tick        SYSTEM DEF, Auto E85 Mix Adj
(Untick)    SYSTEM DEF, Man E85: AN1 is Mix)
(Untick)   SYSTEM DEF, NAFRIN is ANA#2)

 

E85 AFR WINDOW: This allows the AFR to change in small amounts before the fuel is changed.
PARAMETER, E85 AFR Window
A setting of 0.3 AFR is a good start. The actual setting depends on the OEM ECU regulation!

E85 ADJ Time: This is the response time in seconds of the fuel adjust.

COLD START map.
The Default setting is a good start!

SMT-FTX Fuel Tuner - F12 - E85 Cold Start