¶ Engine Constants
¶ Overview
From the Settings menu, select Constants
Here you need to setup the engine constants. Fill out the fields in the bottom section before calculating the Required Fuel.
¶ Configuration
¶ Required Fuel Calculator
The required fuel calculator determines the theoretical fuel injection time that would be required at 100% VE. This is determined by knowing the engine capacity, the size and number of the fuel injectors and the number of squirts that will be performed in each cycle. Increasing this figure will lead to an overall increase in the amount of fuel that is injected at all points of the VE map (And vice versa).
You should set all the values in the
Settingssection below before performing theRequired Fuelcalculation
¶ Settings
- Control Algorithm: The load source that will be used for the fuel table
- Squirts per Engine Cycle: How many squirts will be performed over the duration of the engine cycle (Eg 720 degrees for a 4 stroke). most engines will not require values greater than 4. For sequential installations, this should be set to 2 with the injector staging set to 'Alternating'(Internally Speeduino will adjust the squirts to 1)
- Note that for 3 and 5 squirts, you must have a cam signal in addition to the crank.
- Injector Staging: This configures the timing strategy used for the injectors
- Alternating (Recommended for most installs) - Injectors are timed around each cylinders TDC. The exact closing angle can be specific in the Injector Characteristics dialog.
- Simultaneous - All injectors are fired together, based on the TDC of cylinder 1.
- Engine stroke: Whether the engine is 2 stroke or 4 stroke
- Number of cylinders: Number of cylinders in the engine. For rotary engines, select 4.
- Injector Port Type: Option isn't used by firmware. Selection currently does not matter
- Number of injectors: Usually the same as number of cylinders (For port injection)
- Engine Type: Whether the crank angle between firings is the same for all cylinders. If using an Odd fire engine (Eg Some V-Twins and Buick V6s), the angle for each output channel must be specific.
- Stoichiometric ratio: The stoichiometric ration of the fuel being used. For flex fuel, choose the primary fuel.
- Injector Layout: Specifies how the injectors are wired in
- Paired: 2 injectors are wired to each channel. The number of channels used is therefore equal to half the number of cylinders.
- Semi-Sequential: Semi-sequential: Same as paired except that injector channels are mirrored (1&4, 2&3) meaning the number of outputs used are equal to the number of cylinders. Only valid for 4 cylinders or less.
- Sequential: 1 injector per output and outputs used equals the number of cylinders. Injection is timed over full cycle. Only available for engines with 4 or fewer cylinders.
- Board Layout: Specifies the input/output pin layout based on which Speeduino board you're using. For specific details of these pin mappings, see the utils.ino file
- MAP Sample Method: How the MAP sensor readings will be processed:
- Instantaneous: Every reading is used as it is taken. Makes for a highly fluctuating signal, but can be useful for testing
- Cycle Average: The average sensor reading across 720 crank degrees is used. This is of Event average are the recommended options for 4 of more cylinders
- Cycle Minimum: The lowest value detected across 720 degrees is used. This is the recommended method for less than 4 cylinders or ITBs
- Event Average: Similar to Cycle Average, however performs the averaging once per ignition event rather than once per cycle. Generally offers faster response with a similar level of accuracy.
- MAP Sample switch point: Instantaneous MAP sampling method is used below this RPM and the selected method is used above this RPM. Default value: 0 RPM. This can be used to improve low RPM thorttle response, by using instantaneous MAP sample method around idle RPM for fastest MAP response and then switch to other methods at higher RPM to get rid of the MAP noise that instantaneous mode can have.
The Oddfire angles should only be used on oddfire engines (Primarily some specifica V6s)