I was over on honda tech, and some guy was talking about how he is getting horrible mpg's.

Some guy said, "i averaged about 31-32mpg on it for the first 2k miles or so. i added the spoon high flow filter (along with b pipe and axle back) and my mpg jumped to constant 34 mpg or better.....i shift at 3k (when i care about gas mileage) and sit at 70 mph on open highways (just above 3k on tach) i have a manual 5 speed."

I thought an air intake lowered your fuel economy. Because it made the air colder so your car's O sensors would add more fuel

Do only certain air intakes lower economy?

 

intakes won't affect how hot/cold air is in the exhaust......you could put 30* air into teh combustion chamber, but it's still going to get ignited and be extremely hot leaving hte exhaust port.

but, why WOULDN'T it give better gas mileage? you're taking out restrictions and letting hte engine work more efficently.

 

i want to say yes to your answer, becasue since my fujita intake install my gas milage has really really dropped. I mean i love the product sounds nice, but even driving it at under 3k rpm, it still does not give me the same milage as stock filter. I mean it should save gas, since when i installed my injen CAI on my gs-r i got way better gas milage, my 92 gets better milage than my 07, and i'm in constant vtec with my gs-r.

 

it all depends on how you drive your car. your mpg wont go down by getting a intake. it will go up or stay level. unless you hot rod your car

 

Anything that makes the car more efficient should in theroy give you more mpg assuming you keep your foot off the pedal.

 

More air going in has a need for more fuel to be mixed with it.
Less gas mileage.

 

Keeping "your foot off the pedal" will get you GREAT gas mileage until the big rig behind you squashes you flat. jk.

 

MORE air does not go in. The same amount of air goes in with less restriction, making it easier for the engine to make more power with the same amount of fuel. Even with my poorly designed K&N SRI, the engine is more powerful without a negative effect on mpg. It is the same, and sometimes slightly better, than before the intake mod.

 

Think of it this way, if you were to take a drink and drink it out of a straw until it filled up your mouth, then take the same drink and drink it without a straw by just tipping it in your mouth and it will fill your mouth much faster but it's still the same ammount of liquid. This same principle applies to an air intake. The intake valve is only going to let in as much air as it wants, with the stock airbox to get that air it needs it would be like sucking the drink through a straw, with a high flow intake it would be taking the same ammount of air it needs but by "gulping".

The only time the air in the intake chamber is really different is when you go forced induction which, as the name implies, forces the denser air into the chamber.

 

since I have gotten a yes and a no, and both sound legitimate, We should send this to the mythbusters! lol

 

Or, you could trust the dyno. charts from the intake manufacturers. K&N lies about their products, but I doubt that the same is true for all of the intake makers, particularly H-FIT.

 

Where are these found? (will you send me some links?)

 

from my experience with my car, i've been getting better gas mileage, better airflow and less restrictive than the stock airbox. The sound of the intake makes me wanna step on the gas harder but i try to avoid it and drive normally.

 

The reasons intakes (and turochargers) lower fuel economy is because they make the engine too efficient, the driver enjoys the extra torque, and ends up abusing its newly found efficiency and revs harder than he normally would.

The RDX gets complaints of low mileage ~15. Me and my mom drive light and it gets 19 mpg, which is impressive for a car that big. That's better than the mazda MPV (it's a V6, which also might have to do with it)

 

my friend kinda explained it to me. He said that it will increase your fuel economy if you drive normally, but if you mash the pedal then it will lower your fuel economy worse than if you didn't have it in.

What kinda intake do you have? don't say stock or oem either.

 

the only reason that your fuel economy will go down when you get an intake is because you will have more of a tendency to step a little harder on the petal to hear the deep throaty sound your car now produces.

when i first got my intake on my integra, my fuel economy went way down and i was like wtf?

after a while i started driving like a sane person again and i started getting better gas mileage than i was before the intake.

 

If you have a less restrictive system why wouldn't more air go in? If you are pouring water out of a tap and you reduce the restriction (by opening the valve) then more water comes out of the tap. Same thing if you reduce the electrical resistance in a circut, you increase the amps.

Another consideration I guess would be if you are drawing in colder air through a CAI. It is more dense and technically more air goes for the same amount of volume. Enough to actually affect your MPG, maybe.

My own experience with my Fujita CAI is a slight reduction in MPG around the city, however a signifigant increase in economy on the highway.

 

IMHO, you will only get more air at WOT. The throttle plate still restricts the air intake during normal driving. The ecm determines the optimal fuel air mix based on the mass air flow reading, O2 sensor feedback and throttle positon.

If you have a less restrictive intake, you will get more power for the same throttle position (but also more fuel consumption). The ecm will prevent the engine from running too lean with the higher air flow. Of course this doesn't consider any changes to the intake resonance. But the O2 sensor will still adjust for it.

 

i'd have to disagree on that one, if thats true.....then there is something truly wrong with my new fit. because i baby that gas pedal soooo much and still get very bad gas milage.

 

you just can't change part of the car and say this or that will or won't happen without supporting data or computer analysis, etc. everything from air flow/density/temp/resistance, combined with the computer fuel map, intake and exhaust resonance and ideal sustained flows, transmission gearing and losses, steady state rpm/hp/torque figures... it's really kind of unpredictable until someone tries a specific change.

my best guess is anything that can aid low end torque/hp for the Fit would help mpg. a free flowing intake helps reduce pumping losses.

the new civic 1.8L actually runs atkinson cycle (stolen from prius gas engine) instead of otto for increased cruising economy, plus dual length intake setup. pretty slick.

* otto cycle is the traditional suck squeeze bang blow. atkinson is when the intake valve is open during part of the squeeze.