Turbos improve or worsen fuel consumption?

[RigerZ]

So I was reading a bit about turbos and F/C:

One side says that turbos help make use of wasted heat energy and exhaust gases as well as increasing volumetric efficiency, thus making then engine more efficient and saves petrol. This is the case when comparing, say, a turbo-ed 1.6 vs an N/A 2.0 with the same power output.

The other side says that because you increase the volume of air going into the engine when turbocharging, you need to increase the amount of fuel injected to maintain the proper air/fuel ratio, thus increasing fuel consumption.

So, which is it?

Do Small Turbo Engines Really Give Better Gas Mileage?
turbo for increased fuel economy - Ultimatecarpage.com forums
AutoSpeed - Turbo'd for Fuel Economy

 

[stupidcar]

Depending on tuning, I believe it makes the car more fuel efficient.
Don't say big horsepower la.

 

[ixeo]

Both. At the end of the day your right foot determines how much fuel it consumes. For a small turbine car, if you drive normally it will net you better fuel consumption, look at all the modern BMW engines, new 3 series and 5 series have better emissions and fuel consumption than their predecessors which had bigger displacement but naturally aspirated.

Likewise when you drive it like you stole it, turbocharged cars can run higher boost (depending on tune) and in return, give you more power with increased fuel consumption.

Regardless of what it is, turbocharged engines are more efficient than naturally aspirated ones.

 

[wsonny]

which mean if i adjust it to lower boost then then the FC will be better then higher boost...

 

[mADmAN]

i met a dood who has a satria neo....

he said to me when he BOT his engine.. his full tank of fuel could last him hell of alot more compared to when he was N/A...iinm it was a diff of about 150km per tank (maybe more? forgot already la)....makes sense since the engine is making more power hence will require less effort to push the car....less effort will require less fuel.

 

[peterj]

some jokes, apply to my car last time btw, the jokes is after turbo one tank can last few weeks longer then n/a, cause always park in house only

but seriously, that only apply to high boost car > 0.7bar .... and always wot to full boost then the car need more fuel to feed the "snail" and cool down engine that is why consume more fuel... and if turbo car stuck in traffic jam whereby engine bay temperature is far more higher then cruising on highway, fuel consumption suffer also...

however, if not always wot, stay out of boost and not stuck in traffic for long time, the fuel consumption is actually 20-30 percent better then n/a and it is very obvious on highway cruising (personal experience on 2 4g63t and 2 b16a turbo one vtec and one non vtec).. but personally think gearbox ratio play role also, for honda b series due to i did not change to longer ratio, the short ratio cause the fuel consumption bit higher then the 4g63t...

one obvious example is where i saw my friend do tuning on his avanza 1.3 manual bot, stock n/a normally he tune the air fuel to be around 12.5-13.5 .. while low boost when b.o.t, he make it just rich little then n/a 12.5-13.0 i think, but require lot of ignition timing retards since using 95 pump fuel and the car always drive in town area, but according to him and his wife, save fuel

 

[Waiora_ProTuner]

Turbo for sure have better consumption...

No time to explain...berbuka dulu...

 

[egb18c]

For me. They reduce the mileage because of low compression piston. Its like driving a under powered car.feels heavy. Once the turbo has right amount of air flow,it starts to get more efficient.

Technology now days make engine with high compression engine which makes better drive at low rpm and at high rpm the turbo takes over.

 

[ken yeang]

Simply saying turbo improve or worsen fuel consumption is too general.

just like....

Simply saying eating 3 bowls of rice in every-day cannot mean it is good for health or not.

 

[peterj]

For me. They reduce the mileage because of low compression piston. Its like driving a under powered car.feels heavy. Once the turbo has right amount of air flow,it starts to get more efficient.

Technology now days make engine with high compression engine which makes better drive at low rpm and at high rpm the turbo takes over.

low comp also wont affect responsiveness of the car if only if suitable turbo size is applied depend on your application... for example, my friend avanza bolt on his k3ve stock internal with a compression 10:1 perhaps with k3vet turbo kit, 5 years running fine till now with emanage of course, responsive and fc is good...

another current example is the cfe of proton, if not wrong they leave compression 9.0:1 , however with a suitable turbine , they made the preve and exora lower end responsive like a 2.0L....

however, if the application is in term of racing,while tons of boost and big turbo is used, the words save fuel is not inside the bible of extreme racing,even F1 also done tons of R&D to make their car's fuel enough to finish on the race with the current one time refill rule:wavey:

quote from my friend "you want raise tons of horses, you gonna feed them tons of grass"

 

[vr2turbo]

Problem is even when turbo is fuel efficient the driver is not.
Once you feel the power you want more and more......hahahahahha

 

[RENESIS VIII]

Depends on your boost level I guess. If you are comparing a NA engine with turbocharged engine with same cc, most likely the NA version will be more fuel efficient. Let's say like 4G93 VS 4G93T...

 

[gunnerzz]

I do believe its down to the tuning of the engine such as the boost level.
If its tune for power or higher boost then surely with or without turbo the fc will be high. Its simple concept of when u want more power u have to burn more.

Nowadays, engine like Ford's Ecoboost is and example of having ample power and at the same time great fc.
Same goes for NA car with the Mazda SKyactiv, running super high compression to increases power while burning the same amount of fuel with a normal engine. This in return improves fc as the engine is not worked hard, its not design to be quipped in performance car either. However, i do believe the component is under a bit more stress compared to normal engine. Same goes for Ecoboost.

Then there are VNT (Toyota) and VGT (Mitsubishi).
I have experience a normal turbo Hilux and the VNT and was surprised of the difference in FC. The VNT fuel gauge is very2 reluctant to drop even when the car is pushed hard.Power in much more...ummph.

Some might say that the turbo in CFE engine does not seems to contribute to great FC.
IMHO its not due the engine design and boost level. Its due to the CVT gearbox which just waste lots of power and fuel when below 2k rpm. So the GB also plays a role here.

 

[peterj]

Problem is even when turbo is fuel efficient the driver is not.
Once you feel the power you want more and more......hahahahahha

totally agree it is like alcohol , this one we can easily become boostaholic

 

[egb18c]

low comp also wont affect responsiveness of the car if only if suitable turbo size is applied depend on your application... for example, my friend avanza bolt on his k3ve stock internal with a compression 10:1 perhaps with k3vet turbo kit, 5 years running fine till now with emanage of course, responsive and fc is good...

another current example is the cfe of proton, if not wrong they leave compression 9.0:1 , however with a suitable turbine , they made the preve and exora lower end responsive like a 2.0L....

however, if the application is in term of racing,while tons of boost and big turbo is used, the words save fuel is not inside the bible of extreme racing,even F1 also done tons of R&D to make their car's fuel enough to finish on the race with the current one time refill rule:wavey:

quote from my friend "you want raise tons of horses, you gonna feed them tons of grass"

true that,that what i was saying. Who would put a small turbo with low compression engine or vice versa. It doesnt make sense. Thus it would make turbo engine has low efficiency at certain rpm and high efficiency at certain rpm.

If a stock engine comes with the engineer has studied the balance between power and fuel efficient(responsiveness). Then some wise guy put a big turbo in that car, thus the power band has change to higher rpm. This will cause lack of responsiveness and this will make the driver to put more gas into the engine.

So turbo engine is fuel efficient in stock standard form or on how you drive your car. What makes an engine is efficient is technology. :)