The following procedure illustrates how to create a math channel in Caliper to use your Fuel Flow channel to detect changes within your fuel system.
For Racepak users, click here to learn how to create and view the channel in the DataLink II software.
CC’s Per Turn is a very useful channel, as it is a direct comparison of Fuel Flow to Engine RPM. Therefore, if the value changes throughout the RPM range of the engine, and no bypass jets are being either opened or closed, there may be an issue with the fuel system. When bypass jets are opened or closed (more commonly referred to as “leanouts” or “richening circuits”), the CC’s Per Turn channel will clearly show when these events occur, as there will be marked “steps” in the channel, because the Fuel Flow values change dramatically in relation to Engine RPM.
Looking at the run below, you can see that the efficiency of the fuel pump begins to fall off as the Engine goes above 8700 RPM. After the shift, the RPM drops back down and the CC’s Per Turn continue on at about 9.15-9.20 CC’s.
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 Caliper software. If you wish to add it to your configuration file so the channel will appear in all subsequent downloaded files, select ‘Open 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 ‘Show Channel Configuration’ icon in the upper right corner of the screen.
Click on the '+' button on the right side of the screen. Caliper will ask you to select which type of channel you are adding, either Math or Lookup. Select Math and press OK.
Type the name "CC's Per Turn" in the Name field, replacing the default name (usually "Math Channel 1").
Click on the 'Insert Channel' button and select ‘Fuel Flow’ from the list Then, multiply that value by the constant to convert gallons to CC’s by typing ‘*3785’. Then, divide by Engine RPM by using the ‘/’ character and then clicking on 'Insert Channel' and then ‘Engine RPM’. The completed expression should read as ‘{Fuel Flow}*3785/{Engine RPM} as shown below.
Be sure to set the decimals to 3 significant digits. The minimum value should be set to ‘0.0000’ and the maximum should be set to ’10.0000’ for supercharged gas and methanol and even nostalgia top fuel/funny car. For supercharged nitro, the maximum should be set to ’40.0000’.
Finish off by selecting your favorite color to represent this channel.
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.