Hi, guys! Since I like making tutorials but hate to do voiced-videos, I’m just going to try my absolute best to do some Engine Building 101 classes here on each type of engine and application. I plan on exercising all possible outcomes for each individual type of engine. Before I get started, I want to make it very clear that I will not use quality sliders, but I will suggest where to invest quality for each type of engine.
Please don’t reply to this thread, just send me a PM if you want to request a certain engine type, need help, have a suggestion, etc. Thanks. 
[size=150]Efficient Engines (Naturally Aspirated)[/size]
Achieving high-efficiency is not all that difficult in Automation. The key is using the top fuel delivery methods of that time, low friction cast pistons, high compression, DOHC, 15.0:1 Air:Fuel ratio, moderately advanced timing (81 seems to work best while maintaining compression), and low exhaust diameter. Engines with a large stroke and small bore tend to be more efficient than engines with a large bore and small stroke. This doesn’t influence efficiency too much, so if your engine is not very reliable because of the stroke, reduce the stroke and increase the bore. Invest in the Fuel tab and/or Top End tab for more fuel efficiency. Here is an engine I made that is at maximum efficiency for a 2.0L I4:
