The old system just split fitting the engine to the car into flywheel, starter motor and valves. This always caused a bottleneck and was unrealistic, as nobody actually assembles a car engine in the car. Plus the opportunity to set up a separate line for car engines which then got merged wwith the car sounded like good fun.
After some thinking about the best way to do this, and to retain flexibility and not introduce entirely new levels of confusion and complexity, I decided that handling car engines as a resource (just like steel) made the most sense. That way I could re-use the existing mechanics, and overhead conveyor system, but I could also use this opportunity to introduce extra features to the whole idea of resource objects and upgrades…
In the current version of the game, resource objects are just objects. A chunk of steel is a chunk of steel. It can be used as the input to a slot which effectively turns it into a sheet of steel, but thats it. Any manufacturing upgrades are limited to merely making the steel sheet faster, cheaper or using less power.
I decided we could do better 
Now car features can also be applied to resources. So for example, a manufacturing slot which makes car starter motors (which I’ve renamed ECU, to reflect that this is a more complex and all-encompassing component), can simply churn out ECUs, or it can be upgraded (after the relevant research) to add the ‘stop start’ feature to the component. This means that when that ECU is combined with an engine assembly and Transmission to create a powertrain object, that object also now has the ‘stop start’ feature, and then when it gets fitted to the car, the finished car now has that feature too.
This works with the new engine assembly system as follows:
We have new resource types:
- ECU (previously starter motor)
- Engine Block
- Transmission
A new manufacturing slot produces Engine assemblies by combining engine blocks and valves.
A new manufacturing slot produces drive trains by combining engine assemblies , ECUs and Transmissions.
The old 'fit engine assembly slot now fits the powertrain to the car in a single action.
Eventually I can add new manufacturing slots for the new transmission and engine block, to further flesh-out the whole engine production process.
The only complexity I had left to solve today was to make it apparent to the player what extra upgrades had been applied to resource objects. I decided to use something similar to tooltips, but red, which show up when you select the slot that contains them. For example here is the powertrain construction slot without being highlighted.
And now with.
I don’t yet have new resource graphics for power-train, engine block and transmission, so I’m using my ‘engine’ graphic for all of them for the time being
Feedback and questions most welcome. This is aimed for 1.15.
