Originally Posted by ilikehonda

thats not how it works. you are still using more fuel because you are forcing air into the cylinders. with a small turbo like you said it will spool much quicker than a large turbo meaning if you were driving 70mph on the highway you would most likely be in boost the entire time...therefore getting worse gas mileage. the motor doesnt have to work any easier to make 150 hp na or 150 hp with a turbo. do some more research on turbos and how they work. go and buy corky bells turbo charging book.

you could potentially get similar gas mileage...possibly even the same....but not more.

even if you could get 5 mpg better the 3k you had to spend to get there wouldnt be worth it. 5mpg x 20 gal tank (thats a big *** tank) = 100 miles per tank or you saved 40 dollars (gas at 2.50/gal)

that is 75 tanks of fuel before you reach the benefits.

the accord is 17.1 gallons so 85.5 miles to the tank or 34 dollars you save over the old mpg. 88 tanks of fuel to get the money back. that is almost 53k miles before you save 3k. but what about the extra cost for oil for the turbo? etc...just not worth it.

Originally Posted by ilikehonda

thats not how it works. you are still using more fuel because you are forcing air into the cylinders. with a small turbo like you said it will spool much quicker than a large turbo meaning if you were driving 70mph on the highway you would most likely be in boost the entire time...therefore getting worse gas mileage. the motor doesnt have to work any easier to make 150 hp na or 150 hp with a turbo. do some more research on turbos and how they work. go and buy corky bells turbo charging book.

you could potentially get similar gas mileage...possibly even the same....but not more.

even if you could get 5 mpg better the 3k you had to spend to get there wouldnt be worth it. 5mpg x 20 gal tank (thats a big *** tank) = 100 miles per tank or you saved 40 dollars (gas at 2.50/gal)

that is 75 tanks of fuel before you reach the benefits.

the accord is 17.1 gallons so 85.5 miles to the tank or 34 dollars you save over the old mpg. 88 tanks of fuel to get the money back. that is almost 53k miles before you save 3k. but what about the extra cost for oil for the turbo? etc...just not worth it.

Originally Posted by DREADxPIRATE

...
As long as you're not heavy footed and trying to accelerate faster than you did before, the MPG will increase.
I said a small turbo because it is best in terms of acceleration; i.e. city driving. I had forgot that he had a long commute, so I guess that means highway. But that shouldn't really make much of a difference- maintaining a constant speed requires much less engine power as the engine must only overcome friction, both aerodynamic and kinetic, whereas acceleration also includes inertia as a factor. Less power means less air and fuel needed, so highway mpg should be roughly equal to what it is now. But a larger turbo would be more effective in this situation.
Also, at a constant speed the turbo won't be making hardly any psi.

Cliffs: I know what I'm talking about.

Originally Posted by FijiBlueFG2

If you want to increase fuel economy, remove your catalytic converter.

Originally Posted by ilikehonda

you obviously dont know that you are talking about.

Originally Posted by ilikehonda

for instance my h22 turns 3.5k at 70 mph. if i were running a small turbo say t25 i would also be boosting at whatever level i had set the wastegate. That turbo will have full boost at 3 k on a larger displacement 4 banger....and even lower the more cylinders you add. even larger turbo's could be trying to run boost at that rpm.

Originally Posted by sup3rd

Say what?

How does running no cat give you better fuel economy when the gas has already been burnt prior to passing through the cat? On top of that running without a cat will cause you to run rich. Unburnt gas ftl

Originally Posted by FijiBlueFG2

Its difficult to describe, but basically, the engine needs a higher amount of fuel, to burn all of the gasoline prior to emission, than on a catless vehicle.

Originally Posted by 90sedan

Actually you don't know what you're talking about. For a turbo to make boost there needs to be engine load. Just as you can't rev your engine and make full boost. So your example is incredible wrong.

Sure that t25 would make full boost around 3500rpms, if there is enough engine load. However just cruising will not produce any boost, even if you are cruising at 8000rpms, the turbo will not make any boost until you produce more load, ie. give it an increased amount of throttle.

You've obviously never owned anything turbo'd because you would know that you aren't in boost 100% of the time.

You can drive around without hitting any boost at all, its really easy, i do it all the time, you simply just don't "smash the gas".


If the car is properly tuned with a turbo set-up and you drive normally, there will be an increase in mpg's.

Originally Posted by ilikehonda

so why dont turbo cars get better mileage than their na counter parts? ie the early eclipses? gst's got worse mileage.....or the new cobalts? my turbo car never got better gas mileage....no matter how i drove it.

Originally Posted by DREADxPIRATE

Couldn't have said it better myself.



Most turbocharged production cars (that also have NA engines available) normally have a completely different engine. If it is based off the same engine (which is relatively rare), then it is normally heavily modified so that it will be as reliable as possible- this may lower the mpg.
But it is still all about how one drives. My friend can get ~25 mpg city in his 09 WRX when he shifts early and drives like he's 90 years old. The EPA estimate is 18.

Originally Posted by ilikehonda

with a small turbo like you said it will spool much quicker than a large turbo meaning if you were driving 70mph on the highway you would most likely be in boost the entire time...therefore getting worse gas mileage.

Originally Posted by ilikehonda

neither the gst nor the cobalt have different engines (although they are available). like i said my turbo car never got the mileage it did stock......but guess that doesnt count.

no matter how you look at it turbocharging a car to get better gas mileage is pointless. simple mods like intake and exhaust will do more than any "gas saving turbo setup". not to mention the cost savings.

any one can drive a car to get better gas mileage...not just on turbo cars. my car is rated at 28 hwy and i got 31 my last trip.