I know that if you add a good cold air intake, synthethic oil, new tires and reduce the weight of the car you can get better miles per gallon.

I am not sure what would happen if a turbo or a supercharger would change this however...

If you add a turbo or a supercharger which gives you more power does that mean you use the same amount of fuel but get more energy? If that's true then would adding a turbo get you better miles per gallon of gas? Or is it less....? Anyway how does a turbo or supercharger affect the MPG in a car?

I know that if you add a good cold air intake, synthethic oil, new tires and reduce the weight of the car you can get better miles per gallon.

I am not sure what would happen if a turbo or a supercharger would change this however...

If you add a turbo or a supercharger which gives you more power does that mean you use the same amount of fuel but get more energy? If that's true then would adding a turbo get you better miles per gallon of gas? Or is it less....? Anyway how does a turbo or supercharger affect the MPG in a car?



No forced induction has to be compensated with additional fuel otherwise it will run extremelly lean and cause detonation.

So superchargers or turbos will kill your gas mileage under boost.

well a turbo and supercharger will kill your gas mileage if your boosting like what neutrino said. but when you just cruise off boost, the gas mileage is more or less the same as it was before the forced induction. and if you have bolt ons, i/h/e that will help you get better mileage to becuase its helping the engine breathe more efficiently.

With super-chargers and turbo-chargers you're forcing more air into the cylinders, which means that more fuel will have to be used to maintain a proper air/fuel ratio. If you did not add more fuel then you would run lean, which is very dangerous and, as Neutrino said, will cause detonation. However, with centrifugal type super-chargers and turbo-chargers they will only boost under load, which would really only be during acceleration and driving up hills. Only under boost will the computer compensate with more fuel. So when you're cruising at a constant speed or decelerating it is as if the turbo isn't even there. You can even manage to accelerate without boosting sometimes. However, with a roots type super-charger you're always boosting. It doesn't matter if the engine is at idle, under load, cruising speed, or decelerating the super-charger is going to be boosting though at idle, cruising, and decelerating it will be a small amount.

So with forced induction you can still have good fuel mileage, as long as you're not throttle happy.

Also, we have a sub-forum devoted to forced induction. I'll move this thread there.

why go turbo and not floor it 90% of the time?

No forced induction has to be compensated with additional fuel otherwise it will run extremelly lean and cause detonation.

So superchargers or turbos will kill your gas mileage under boost.
The specific fuel consumption will however be lower.

Centrifugal superchargers and turbochargers really dont kill a lot of mileage if your going the alley speed limit(5mph).But if you floor it,you better be heading to the next Chevron.

The specific fuel consumption will however be lower.

Are you refering to fuel consuption/power?


Centrifugal superchargers and turbochargers really dont kill a lot of mileage if your going the alley speed limit(5mph).But if you floor it,you better be heading to the next Chevron.


Well to be more specific. The superchargers are directly RPM dependant so even if you floor it but keep it at low RPM super's will put out very low boost.

On the other hand turbochargers are load dependand so as long as you accelerate gently and keep a light foot on the pedal the boost will be low almost regadless of the rpm and if you go WOT it will start some serious boost at even very low rpm.

Are you refering to fuel consuption/power?





Well to be more specific. The superchargers are directly RPM dependant so even if you floor it but keep it at low RPM super's will put out very low boost.

On the other hand turbochargers are load dependand so as long as you accelerate gently and keep a light foot on the pedal the boost will be low almost regadless of the rpm and if you go WOT it will start some serious boost at even very low rpm.
Specific fuel consumption = fuel consumption per produced power (usually g/kWh).

Specific fuel consumption = fuel consumption per produced power (usually g/kWh).



I though that was what you meant. Just wanted to be sure. And i agree with you that turbo cars are more efficient.

why go turbo and not floor it 90% of the time?

Because you might want the car to last for more than 50,000 miles not to mention the fact that we have enough crazies on the road.

SJ - since when is kWh power?

SJ - since when is kWh power?
kW is power produced by the engine, h relate to that the power is produced for one hour which is neccesary for the specific fuel consumption.