You may have an aircraft with a modified or non-certificated engine added to that airframe. Same with the prop. That's alright - you can add these by looking up the make or model vs. selecting the suggested TC'd engines.
First, select the "+" button in the Engine or Prop Tabs from your aircraft profile to bring up the search page to add selected engines or props, i.e. for engines:
As an example, there's a conversion kit (STC# SA1437CE) for the Cessna 172 that allows you to upgrade to a 210 HP Continental engine (IO-360 K or IO-360 KB). If we wanted to account for this, we'd add it manually.
To add a non-TC'd engine to your aircraft profile, look up your engine using the make/model: REMEMBER: less is more. Start searching the model name first to see what comes up (i.e., "IO-360" in this example):
Searching for IO-360 :
we'd then scroll down and select IO-360K and then hit the add selected Engine button above:
Hit the button "Add Selected Engine":
And then you'll see it appear on the right:
If there's a random engine or prop that you need to add that is not in the system - please contact us.