The following procedure illustrates how to create a math channel in the DataLink II software to use your Boost PSI and Fuel Flow channels to detect changes within your fuel system.
Boost to Fuel Ratio is very useful, since O2 sensors are not reliable in a supercharged methanol application. The reason for this is that in most supercharged applications, the engine is over-fueled, as some of the methanol goes towards cooling the inlet charge as well as sealing the supercharger. Due to this, in addition to the latent heat of vaporization of methanol, the air/fuel ratio often goes beyond the range of a traditional O2 sensor, which typically tops out at .65 Lambda, or 4.2:1 in the case of methanol, which has a stoichiometric air-fuel ratio of 6.4:1.
Looking at the data below, you can see that the Boost/Fuel Ratio varies from 2.71 to 2.92 throughout the course of the run on this particular vehicle.
To add this channel, first open the file to which you wish to add the new channel. If it is a run file, simply open it from the ‘File’ menu in the DataLink II software. If you wish to add it to your configuration file so the channel will appear in all subsequent downloaded files, select ‘Open Car Configuration’ from the ‘File’ menu, and select the appropriate configuration file from the available list.
Once the desired file has been opened in the software, select the ‘Channel Maintenance’ option under the ‘Edit’ menu.
Click on the channel in the list where you would like to insert the new channel. In this example, we will be placing it immediately after the ‘Fuel Flow’ channel, so we will highlight the next channel in the list (‘TDC RPM’). Click on ‘Easy Insert Channel’.
Now we need to select the type of channel we will be inserting. Since we are going to create a simple expression, we should select ‘Calculation’ from the list and then select ‘RATIO’ as the type . Click ‘OK’.
Name the channel ‘Boost/Fuel Ratio’, or something similar. Select 'Boost Press' by clicking on it in the 'Divide Channel' in the left-hand column and the select 'Fuel Flow' by clicking on it in the 'by Channel' in the right-hand column. Set any number of digits before the decimal point and 3 after. You don't have to enter a Unit, although some use 'Air/Fuel' in this field. In the Maximum result value field, enter '6' for supercharged methanol. When complete, the channel should appear as shown below.
Simply click ‘OK’ to add the channel to the list, and then ‘OK’ a second time to return to the main screen of the DataLink II software. You should see the channel button ‘Boost/Fuel Ratio’ appear in the location into which you inserted it. If you are satisfied with the results, be sure to click ‘Save’ from the ‘File’ menu.
For questions or assistance in adding these channels to your system, please contact us at Performance Data Systems at (949) 652-6300 or email us at support@racepds.com.