How turbo cars are fuel efficient? help!

[cr8zyjap07]

So im trying to do a paper on how a turbo car can be fuel efficient. I have a good idea on why its fuel efficient but im not 100% sure. if some one can show me some good links containing some solid info or can explain why i would greatly appreciate it.

[The Captain]

What do you mean fuel efficient?

They're fuel efficient when not in boost.

[Fujito]

I wish I could tell you. Mine sure isn't.

[SvicksTc]

there was a whole article in Car and Driver i wish i remember what issue...there is a ton of info out there on this topic....not fuel effiecnet when in boost, however, can be more fuel efficent when not then a naturally aspirated car

[cr8zyjap07]

im sorry, i mean how turbo cars CAN be fuel efficient without a heavy foot. if your not in boost turbo cars are more efficient than normal cars. thats the info im trying to find.

[92sileighty]

turbo and fuel efficient should never be in the same sentence

[Fujito]

They can be fuel efficient if you stay out of boost, which means granny shifting below 3000 RPM in most cases. By doing so the driver is basically driving a slow whatever-it-is. Were you assigned this topic or did you pick it yourself? If it's the latter then you should rethink your topic.

[SvicksTc]

Originally Posted by 92sileighty

turbo and fuel efficient should never be in the same sentence

for ricers like us yes...

[92sileighty]

Originally Posted by SvicksTc

for ricers like us yes...

lol

[cr8zyjap07]

like said above, when not in boost it gets better gas milage than a naturally-aspirated car. my sti gets 32mpg highway(accessport measurement) when driving like a girl then i go in full boost and it gets like 1.6~0.7mpg lol.

[cr8zyjap07]

Originally Posted by Fujito

They can be fuel efficient if you stay out of boost, which means granny shifting below 3000 RPM in most cases. By doing so the driver is basically driving a slow whatever-it-is. Were you assigned this topic or did you pick it yourself? If it's the latter then you should rethink your topic.

i didnt start yet and i wanted to do this topic, i have a list to choose and then i have to break it down to a smaller topic. i was thinking this would be good under environment but i cant find solid info on it so i might just do something else. i was trying to get out easy lol

[KingKong8247]

My mileage went up when I turbod my car but in boost forget it.

[tort9320g]

Google "Turbocharger efficiency" and "How turbos work". Lots of valuable information, you should find what you're looking for there.

Good luck...Dave

[ndubz]

If u stay out of boost it will be kind of efficient. But thats really only by comparison to cars with larger motors that put out the same power. Like my sti averages 20mpg and has a bit over 400bhp, a gto or CTS-V will average somewhere in the high teens, this is because they have 6.0L V8s and my car has a 2.5L flat 4 with a turbocharger. My car gets good milage by comparison to other cars of similar power levels, but at the end of the day turbos are for making more power. They force more air into the motor and more air always requires more fuel, so the answer to ur paper subject is that they dont help gas milage at all. They actually hurt it quite a bit compared to if a car of the same displacement were to be run N/A with a conservative tune that is just meant to be a normal car. Yes staying under boost helps u get better milage, but remember that turbo cars run less compression than N/A cars, so when ur running under boost the cars efficiency is actually down quite a bit compared to an N/A car of the same displacement and layout. Turbos are purely for performance though dude, if u want great gas milage, then get a diesel VW or a prius, or any other little econo box that is designed to use as little fuel as possible and sacrifice performance for economy.

But if ur stuck with this paper, then use the Sti and evo VS mustang and GTO economy comparison. Cars with small displacement turbo engines only have a fuel economy advantage ove cars that put out similar power using much larger motors.

[OMGz Turbo]

Want a great answer??? Ecoboost. Great power with great MPG's

[DPancoast]

lol my gas mileage gets cut in HALF when comparing boost to no boost...

like... I'll get 22-23mpg if I stay out of boost (about 300 miles to 12 gallons), but if I do the same in boost I get about 12-15mpg (about 150 miles to 12 gallons)

[mann]

there are a few theories and you can read Corky Bell's "Maximum boost" to really get a good technical idea, but a turbo is more efficient than NA and SC due to:

1. Small engine for same size HP. An 2.0 inline 4 turbo has less rotating friction and mass than than a similar HP V6 or V8. Even when they "turn off" cylinders in some of the newer ones they have to rotate.

2. Exhaust gas energy. When the byproducts or combustion are released out of the exhaust you have 1500 degrees of heat at a rapid velocity coming out into the atmosphere. That heat energy is thrown away. A turbo will reuse that heat energy to compress the intake charge and shove it into the engine, thereby increasing its overall efficiency. If you are consistently using the engine at its peak power though it will obviousley get worse gas mileage. Power is gas...

3. Turbo vs SC--there are two factors here. First off the SC will need belt drive, and since its not using the exhaust energy it is a parasitic drag on the motor, usually about 10-20%. For example, with a miata at 9 psi with a SC you will dyno 200whp, with a turbo 240whp. Most superchargers are also less efficient then turbos when compressing, and this causes the SC intake charge to be hotter and thereby less efficiency.

The trick is not comparing a 2.0 NA to a 2.0 T, the T will put out more HP, and thereby use more gas. Having the turbo in the exhaust stream is actually a little less efficient since at low loads its actually a restriction. However the 2.0T needs to be compared to an engine of the same HP, not displacement. So if you compare a 2.0T to an NA V6, the turbo motor will be more efficient.

A good analogy is the mazda 6 series. The 2.3 mazda 6 has 21/28 and 160 HP, the 2.3t has 17/23 and 274 HP, the v6 has 17/24 215 hp . You can see for about the same MPG you get a TON more HP with the turbo car (note the 2.3 is AWD and if it was fwd like the v6 it would get another 1-2 mpg at least)

end of FI 101...

[jpalamar]

Originally Posted by ndubz

If u stay out of boost it will be kind of efficient. But thats really only by comparison to cars with larger motors that put out the same power. Like my sti averages 20mpg and has a bit over 400bhp, a gto or CTS-V will average somewhere in the high teens, this is because they have 6.0L V8s and my car has a 2.5L flat 4 with a turbocharger. My car gets good milage by comparison to other cars of similar power levels, but at the end of the day turbos are for making more power. They force more air into the motor and more air always requires more fuel, so the answer to ur paper subject is that they dont help gas milage at all. They actually hurt it quite a bit compared to if a car of the same displacement were to be run N/A with a conservative tune that is just meant to be a normal car. Yes staying under boost helps u get better milage, but remember that turbo cars run less compression than N/A cars, so when ur running under boost the cars efficiency is actually down quite a bit compared to an N/A car of the same displacement and layout. Turbos are purely for performance though dude, if u want great gas milage, then get a diesel VW or a prius, or any other little econo box that is designed to use as little fuel as possible and sacrifice performance for economy.

But if ur stuck with this paper, then use the Sti and evo VS mustang and GTO economy comparison. Cars with small displacement turbo engines only have a fuel economy advantage ove cars that put out similar power using much larger motors.

My GTO gets about 24 highway and 18 city. The EPA estimates are very close on my car. Even when I beat on it hard, it only really drops to about 17. And comparing a small turbo motor to a V8 isn't really a comparision because we have more power at all RPMs, its the equavilent of a I4 turbo under boost at all times which doesn't happen. Hence our fuel economy is typically less.

Bottom line, turbos do not have anything to do with fuel effeciency. They are designed to allow a small underpowered motor to give the needed HP when under harder acceleration. More HP = more fuel needed.

Your paper has fail all over it.

[SheaButter]

Why just focus on gas engines. Look at a turbo diesel's they can actually be very fast and powerful and have over 100mpg. Discovery Channel did a special on this racecar that got 134 mpg and it was a 1.8 turbo diesel. Just a thought for you and ur paper

[Scapegoat]

they are certainly more gas efficient... as in an elemental form. A turbo charged vehicle is making better use of both the incoming and outgoing gases. a turbo charged vehicle isn't just wasting exhaust gas, but using it. making it a more efficient motor. I think we're confusing fuel efficiency and MPG here as well. turbo charged motors are mote fuel efficient by far... especially when you get into tuning and leaning them out to get more power.

we're effectively using a more efficient air fuel ratio than both non-turboed and non-tuned vehicles.

If you make the distinction clear that you're not writing about MPG's but about actually efficiencies with the system, then you will be fine