Can restricting airflow actually increase mpg

[allenh318]

Just had a couple thoughts and am looking for some answers that i am not sure of. If getting more airflow into the intake will increase HP, would restricting airflow decrease the HP of the engine, thus using less fuel to keep the mixture correct? I know the thinking is more HP allows you to keep out of the throttle, but would less hp make your engine act like a smaller engine? The other side of this would less airflow make it run less efficient?

[mcrews]

the simple answer is no.
There have been studies with completely clogged airfilters and the performance is the same as a new filter.

but one of the more 'phD eco-modders' will chime in.

[tortoise]

Originally Posted by allenh318

Just had a couple thoughts and am looking for some answers that i am not sure of. If getting more airflow into the intake will increase HP, would restricting airflow decrease the HP of the engine, thus using less fuel to keep the mixture correct?

Closing the throttle (letting off the gas pedal) will restrict airflow and use less fuel. Also, you'll go slower.

[GRU]

the only way it would help to restrict the engine is if the driver is the type that drives and acceleartes too fast (using up too much fuel) so if you restrict the engine it would force the driver to drive slower.

[tortoise]

Originally Posted by mcrews

There have been studies with completely clogged airfilters and the performance is the same as a new filter.

I kinda think maybe a completely clogged airfilter would give no performance. (But then, I don't have a phD.)

[mcrews]

Originally Posted by tortoise

I kinda think maybe a completely clogged airfilter would give no performance. (But then, I don't have a phD.)

yeah, probably a bad choice of word.

[ksa8907]

on modern fuel injection systems, air filters don't directly affect mileage. the engine will keep the mixture at the programmed ratio regardless of the filter, but a clogged filter will decrease power thus forcing the driver to push the pedal harder to get the same power.

air filter relates to performance and fuel economy is a side effect.

[gone-ot]

phD = "piled higher & Deeper"

[drmiller100]

it takes X horsepower to go a certain speed, or accelerate at a certain rate.

If the air filter is clean and flowing well, the restirction is the throttle, which uses horsepower. If the air filter is mostly plugged, and a huge restriction, then the restriction is the filter AND the throttle, which takes the EXACT same amount of horsepower.

[mwebb]

not by restricting flow
but
possibly by taking the incoming air charge from an area of lower pressure,
like from behind a tire or from behind the car

the difference in pressure would be so small , the gains if any would be difficult to measure .

restricting flow can reduce maximum available power output but can not change FE Unless the system is carburated

2x as per the EPA (which never lies or fibs) and IATn which is more accurate and subject to a demand / need to prove test results .