Engine Design, Performance vs Revolutions slider

[Dolehof]

Durability hits on moving both the torque and RPMs to max is around 10-15 points. That's off the top of my head roughly 50% of the slider changeable durability. The rest of durability is generated from your sub component selection.

I can't see the point ratings in the game, but I noticed my durability star rating went down when I moved the performance slider in design focus panel up, but not when I moved revolution slider in the performance panel up.

If I design a new engine, with all siders starting at 40 and move performance all the way down and compensate that with the revolution slider giving a few ticks up to get back to the rpm I started out with I have a slightly cheaper engine that seems to perform just as well.

Also note, just because an engine has increased RPMs does not mean that its optimal brake specific fuel consumption changes much. Combustion is dependent on Air, Fuel, and Spark. One can adjust the levels of these to provide maximum RPMs, Torque, or even least fuel consumption at certain ranges. Remember, you're seeing Peak RPMs, Peak Torque, and Peak Fuel Economy. These do not all happen at the same time.

I understand that, although I'm not sure about the the Peak Fuel Economy, a well designed gearbox seems to give my cars a better fuel economy than the engine itself. So fuel economy seems to be more of rough indication of average fuel economy with an average gearbox.

(Also note, that a lot of RPM increasing techniques such as reducing piston ring thickness or using thinner oil actually improve fuel economy as well. )

I understand that many of those techniques improve engine efficiency as less energy is lost through friction. A better engineered engine tends to be better I guess )