When is SOHC better than OHC?

First, awesome job guys. Even without many options for now, this game is really fun and promising.
I am building some engines, using the i4 demo for now, that are basically the same except for the head, compression ratio and ignition timing to make the example simpler. I can't make a engine using SOHC that is better than the same engine using OHC, all of the OHC engines are more economical, a little more powerful, cheaper and take a considerable less time to build.
Those are the engines in question, am I missing something? what sort of circumstances using a two valves SOHC head is better than just OHC?
Thanks
Edit: sorry for the grammar, English is not my first language.

I am building some engines, using the i4 demo for now, that are basically the same except for the head, compression ratio and ignition timing to make the example simpler. I can't make a engine using SOHC that is better than the same engine using OHC, all of the OHC engines are more economical, a little more powerful, cheaper and take a considerable less time to build.
Those are the engines in question, am I missing something? what sort of circumstances using a two valves SOHC head is better than just OHC?
Thanks
Edit: sorry for the grammar, English is not my first language.