Turbocharging helping gas mileage?

[chrisofna]

Okay, my friend was telling me that some people who have put turbos on their 3-cylinder Geos record better gas mileage than them being NA. So my question is this: Why would this happen and would it be the same way with a B3, or in my case, my 2.8L in my Cressida (I can build the turbo kit dirt cheap, like maybe $100). My only theory about why it works so well on the 3-cylinder Geos is they are so underpowered that with the extra power with the turbo it can maintain speeds easier and not make the motor work as hard.

[bhazard]

Nope. More air means more fuel.

Engines are also more efficient under load. It gets pretty complicated.

Best thing you can do to improve mileage is maximize low end torque and cruise at the lowest rpms possible without lugging. Cam, timing, tuning, etc. You're metro buddies are only getting better mileage in their heads. They obviously have to richen the fuel mixture to safely boost their NA engines.

[bakerga1969]

I believe they can, colder more compessed air burns more efficent ,as long as they can get the gases out. Just like a cold air intake and header . But even more. But it has to do with timing too. And probally how much boost.

[ToSloTrk]

Yup,I believe that they are getting better fuel mileage.

You should to if you have a fairly light throttle foot. A turbo will lower the amount of energy the engine requires to ingest air even when it's not creating boost(cruising).

Go For It

[chrisofna]

Yeah, I guess I should of meant they get better gas mileage out of boost of course.

[hofficergrover]

My gf's bpt egt is getting better mpg's than when it was na.

[bobbyspider]

yea all i know is that a turbo simply makes the engine more efficient and uses the preasure of the already waisted exhaust to feed your motor. makes your motor more efficient but like james said 2 posts before only if you are not constantly hitting boost and driving heavy footed.

[big_ty2003]

According to Corky Bell "maximum boost" A turbo system can not be constructed to be a fuel saving device.

[bobbyspider]

i agree with him. you cant construct it to be a fuel saving devise because its not its purpose but it does make your engine more efficient as a biproduct. its purpose is not to save fuel but under self disipline you can save mpg's

[bhazard]

It makes the making power part of it more efficient only. Bottom line is more power = more air + more fuel.

[FB71]

colder more compessed air burns more efficent

wrong.

Colder air causes fuel condensation. Essentially, it causes the atomized fuel to form larger droplets, which in turn, do not burn. Only vaporized fuel burns. Atomization of fuel fuel is essential to vaporization. The atomized fuel absorbs whatever heat is present in the air, to change state from liquid to vapor (Latent Heat of Vaporization, basic law of Thermodynamics). If there is less heat in the air than in the fuel, then the reverse change in state occurs (Latent Heat of Condensation). Condensed liquid fuel will not combust.

Now, what may be happening, is that the turbo system is raising the temp of the incoming air, while MAINTAINING air density, not increasing it. This is one of the fundamental principles of adiabetic engine experiments. Corky Bell is correct; simply adding a turbo system will not increase fuel economy. However, by recovering as much heat as possible will increase economy, because the engine is required to generate less heat, thereby consuming less fuel.

Do a web search on "Smokey Yunick's hot air engine".

[resuwrecked]

Don't kid yourselves guys. A turbo is a restriction in the exhaust stream. When you aren't in boost you are killing your volumetric efficiency.
More power requires more fuel. An underpowered car gets better mileage any day WHEN DRIVEN PROPERLY because, it has less power and thus uses less fuel.
Power is power is power... wether its a 1.0 making 100hp with a turbo or a 1.6 making 100hp na, the same amout of bhp requires the same amount of fuel, reguardless. It all comes down to extracting the energy from the fuel and putting it to the road efficiently.
I think the mentioned turbo installers claiming to get better mileage are smoking crack, unless they are using a hx35 sized turbo that the car will never spool, and and exhaust gasses just blow freely past the turbine.

[resuwrecked]

Now, what may be happening, is that the turbo system is raising the temp of the incoming air, while MAINTAINING air density, not increasing it.

Air density would have to increase in order for the temp to also rise. Apparently said metros defy the laws of physics, cool. I want one.

[Gforcefd]

I am just stating what I have seen. Many of the turbo cars in the car club I am a part of actually get better mpg than they did when they were NA. I think part of it has to do with yes your making more horsepower and using more fuel, but the weight of the car is being moved easier with less effort then a underpowered car. Example 1.5L new prius gets better fuel mileage then the older 1.3 model, they found out that the older engine was over working itself to move the car at the same rate at the 1.5L. Just my opinion on what I have seen.

That being said if you have a turbo car you are going to find it hard to stay out of boost and keep your mpg up, not to mention the need for premium fuel, and a good piece of tuning software to handle boost conditions and low boost conditions. You can not just use a piggyback to alter fuel and expect it to be efficient at all.

[resuwrecked]

If you have a standalone you can pull lots of fuel at cruise and idle, run like a 16-16.5 afr and save fuel that way. Still, with a stock/modest tune youre making about the same amount of power when cruising in a na or turbo car, pulling 10-11"hg. The only difference then is that you have a restrictive turbine in the exhaust.
Who wants to turbo a car to putt around and save gas anyway? Lol. I love it when I see my wideband hit 12.5 and tire smoke trailing behind as I leave the gas station.