Tue Jul 01, 2014 11:15 pm by Dragawn
*Sigh* I don't want to give my secrets away before the endurance challenge starts, but I'll give you guys a small insight.
I managed to get a competitive Turbocharged engine for GT2, which complies to the restriction of 30+% economy.
There seems to be a misconception here: Good ol' OHV and pushrod designs may be cheap and reliable, but they have suckish efficiëncy, not only resulting in a general power drop, but also resulting in higher fuel consumption.
Since this game calculates realistic fuel consumption in pretty low revs, it is beneficial to economy to have your high torque as low as possible, so your turbo should pick up as soon as possible. A high AR ratio turbo setup may help pick the turbo to pick up earlier, but, probably due to a less efficient turbine, the engine becomes less efficiënt too at the same time. So if you only consider good economy you'd indeed want a low AR turbo setup, but sadly in even slightly high revs the turbo simply won't be able to provide the engine with enough boost power anymore. This is why I've experimented way before with turbo/NA hybrids with the turbo only acting in low revs, but it simply isn't worth the extra weight/price tag. So in general it's a balancing act, but the golden rule to economy is some good power down low.
Edit: With AR efficiency I meant high AR is efficient in high revs and low AR is efficient in low revs.