Small turbocharged engine is the current trend now and is starting to replace larger naturally aspirated engines. Manufacturer claims it has the same or even better power than its larger counterpart. Today I had nothing to do and browsed Chevy USA’s website. When I took a look on Chevrolet Sonic, I was amazed by this:
Reference: chevrolet.com/sonic-hatchbac … train.html
Chevrolet Sonic is offered in 2 (or probably more) engine configuration. A turbocharged 1.4L and NA 1.8L. Both has same peak horsepower rating but turbo engine attains it at lower RPM and the 1.4L has more peak torque and occurs in lower RPM. The 1.4L turbocharged engine looks better in any aspect. So I tried creating them both in Automation.
Here’s the 1.4L turbocharged.
And here’s the 1.8L naturally aspirated.
Quick comparison to them both
Much to my surprise, the 1.4L is not as good as I imagined. It requires 100 octane gas to attain the desired amount of torque and horsepower and the fuel consumption isn’t that great either compared to the 1.8L version. Sure it has more torque and burns less fuel than 1.8L engine at 2700 RPM, but as we can see from the BSFC graph, it burns fuel like crazy on idle and past 4000 RPM while the 1.8L engine doesn’t use more than 300 g/kwh on 6000 RPM.
Not to mention the 1.4L turbocharged engine costs $358.39 more, heavier, has less MBTF and responsiveness, and more expensive to service.
So… Is there no replacement for displacement?
P.S. if anyone owns a Chevrolet Sonic, do they really require 95 octane fuel? Can they run on 91 properly? It’s amazing that they make such power and torque given their displacement.
Hmm, so where is the turbocharger on the 1.8L engine?
no, I own a 2012 Cruze with the 1.4 Turbo ( same as the sonic)., and I use regular and that’s what the mfr recommended anyway.
and, no there is no 1.8 Turbo on offer by G.M at the moment (in USDM at least.), I would know because I sell them.
I have a sneaky suspicion that the turbo on the 1.4T is of the variable nozzle kind so maybe that explains the huge difference in figures and the high octane gas needed.
There is no turbo on the 1.8 L. The turbocharged engine is 1.4 L
The 1.4L makes the same horsepower as 1.8 L at lower RPM and has more torque at lower RPM.
What surprises me is that the turbochargef 1.4 L runs fine on regular gas as headacheengineering said. Replicating such engine in automation would require the car to use ultimate gas to achieve the desired result.
I think it’s because Automation doesn’t provide a ton of customization for turbos. Many manufacturers use twin-scroll turbos that give the car peak torque starting from a very low RPM while maintaining torque and efficiency across the RPM range. Automation only lets you use single turbos tuned for a specific RPM, so it’ll be difficult/impossible to recreate a lot of real life turbo engines.
Ahh, I was getting confused by the “And here’s the 1.8L turbocharged” note above the picture when I glanced at the post.
Well, one thing you should not forget though is that the turbo engine you built there will give the car significantly better performance than the larger NA version because of the convex torque curve - just put them into a test car to try them out. Also take a look at the Power/Torque video I made a while back, if you haven’t seen it yet: youtu.be/vX8wlkSDwSY
You guys are right about the turbos in Automation though, it is but the simplest variant that is available right now, so I don’t think it’s even possible to compare Automation’s turbo-engine figures to modern turboed engines.
Cheers!
Yeah, I think without twin-scroll turbos and a few other bits of magic it’s a bit hard to make turbos spool well enough. That’s something we need to look at eventually 
[quote=“Killrob”]Ahh, I was getting confused by the “And here’s the 1.8L turbocharged” note above the picture when I glanced at the post.
Well, one thing you should not forget though is that the turbo engine you built there will give the car significantly better performance than the larger NA version because of the convex torque curve - just put them into a test car to try them out. Also take a look at the Power/Torque video I made a while back, if you haven’t seen it yet: youtu.be/vX8wlkSDwSY
You guys are right about the turbos in Automation though, it is but the simplest variant that is available right now, so I don’t think it’s even possible to compare Automation’s turbo-engine figures to modern turboed engines.
Cheers![/quote]
Whoops! My mistake. It’s corrected now. The 1.8 L is supposed to be naturally aspirated. Don’t you worry, I know the basic concept of torque vs horsepower. I agree that the 1.4L feels faster from 2000 RPM upwards but it’ surely slower from stop and uses more fuel on traffic jam.
Hopefully more advanced turbos and technologies are implemented when the game is finished 
Is twin scroll turbo something like VGT or VNT (Variable Nozzle Turbo)? My 2500 cc diesel car has VNT and it produces 343 Nm of torque at 1800 RPM which is nice!
I drive a 2012 Sonic with the 1.4L Turbo engine.
The car generally has more power available, but spends less fuel most of the time, compared to the NA 1.8L engine. You see the same two engines in the more popular Chevy Cruze, with the same results. Normal driving you don’t really get into boost at all, and get the benefit of a smaller engine. When you need to accelerate quickly, the tiny turbo brings the boost up fairly rapidly and you’ve got substantially more power than the 1.8 could ever give.
I’ve then modified the car, putting in a larger diameter exhaust, larger intake, larger injectors, a flex fuel sensor, and clipped the turbocharger so it will spin faster.
The car runs fine on 87 octane gas, a little better on higher octanes… but on E85 (85% ethanol 15% gasoline) it tops out at 206hp and 212 ftlbs of torque (sorry about the imperial units)
Driven with a light foot and a little care, I get a consistent 40mpg. Running E85 and driving like I stole it, I get 22mpg. The boost lets you spend gas like you had a much larger displacement engine… with all the power and lousy mpg that comes with that.
