Economy

[vrmcardoso]

First of all, I'm sure this has been discussed before, so I appologise in advance. But I looked and I looked and didn't find anything (okay I didn't look that much, but that's just because the search tool wasn't very helpful)

I dont get the economy stat on the engines. I mean, g/kwh is pretty self explanatory, but how come my performance engine and my economy engine have similar economies (Maybe because I suck, let me know if thats the case)

To be more specific, here are the engines:
2.0L I6 Turbo with 346HP has an economy of 15,14%

0.9L I4 Turbo with 95HP has an economy of 15,29%

Also, to make things more confusing to me, theres my middle ground engine:
1.5L I4 NA with 88HP has an economy of 17,52%
Sure, this one doesn't have a turbo, but its much bigger than the economy engine and apparently its consuming a lot more. But most of all, how is that 346HP beast consuming the same as my 0.9L shoe box?

[pyrlix]

Thats not the economy, its the efficiency The stat its a bit confusing... but it is being measured in the Cruise RPM Range, which is 1500 to 2500ish RPM.

I'll give you a small explanation on Efficiency of Petrolengines. May sound confusing or complex... (Killrob please dont beat or kill me for errors, correct them if they exist )

Lets say you have an engine. And some Fuel, 27 Litres of petrol to be exact. Petrol has... around 10kWh of Energy per Litre (or per 780grams).
This particular engine produces whopping 74kW and when running on peak power, it sucks the 27L canister empty in just 2 hours. Which results of 108kWh of Output Energy in these 2hours.
The Result is: 270kWh of Input, but 108kWh Output. You obvioulsy lost energy (heat, friction etc.)... And if you divde the Output by the Input, you get the result 0,4. Thats your Engine Efficiency there - 40%.
Just tells you how efficient your engine is, the higher the better. But dont ask me how Automation calculates that XD

To your 3 engines:
The 346HP Engine is economic in the Low RPM Range, until you stomp it. The same for the 95HP engine. These are the kind of the downsizing engines that would be used in a lets say Golf. Once as GTI, once as Blue Motion.
And why do you think that the 88hp consumes more? Its more efficient, it should consume less fuel in a car, in the same car, with the same Gearbox, and penalty weight for the 95HP engine...

Hope I could help (and confuse you a bit XD)
//Pyrlix

[vrmcardoso]

Haha! Got it. I assume fuel consumption will be a stat for the complete car, then. Makes sense.

About the 1.5L consuming more, that was a typo. I meant to say I didnt understand why it consumed less than the 0.9L

But now I understand its just more eficient. Which is entirely possible.

Thanks man!

[Der Bayer]

I'd like to add another point: When you are cruising at 100 km/h, you need a certain amount of power to keep your speed because of rolling friction, drivetrain friction and air resistance. Let's say you need 20 kW and your gearbox is set up in a way that you are running at 3000 RPM when going 100 km/h. A very small engine, which makes exactly 20 kW at 3000 RPM at full throttle, will probably be highly efficient because the throttle is open and the engine does not have to suck air against a partially closed throttle. If you put a powerful engine into the same car, you still only need 20 kW for cruising. So if it makes 200 kW at 3000 RPM and full throttle, the throttle is only about 10% open while cruising. So the engine has to suck air through a nearly totally closed throttle and efficiency gets worse.

Looking at a BSFC graph will hopefully make the low efficiency at partially closed throttle a bit more understandable:

1-s2.0-S019689040900096X-gr3.jpg (39.58 KiB) Viewed 2173 times