I'm not sure what you mean. Are you saying that it takes less HP to pull in the air, so it should be more efficient and use less fuel?
if thats what you mean than I agree.

 

While it takes less press of the pedal down to keep the car going a steady speed on the highway, it'll still take the same amount of horsepower. If takes 40 horsepower to keep it going steady, you might have needed to do 20% pedal before and 19.97% after, it still takes the same amount of horsepower, and hence the same fuel, to make the car stay the same rpm. Of course this is basing it off the fact if the computer is still running the same A/F before and after the install. The car is more efficient in means of having to open the throttle less, but not in the fuel econ sense.

A motor is not pushed that hard to draw in air driving normally on the street. When the throttle is 100% open is when the restrictions become obvious and you actually gain power from an intake. Driving around town your never more than 20% open on the throttle so its not having to struggle for air and the gains are minute.

 

Look at it this way...you add more air into your engine what does that do to your A/F ratio? Right, it leans it out. Now how does a proper ECU take care of the leaner mixture? Right again, it adds more fuel. Now explain to me how that = better gas mileage. You are using more gas are you not? Again, go take any basic engine building class and then see if you can argue your point to me. And no, more efficient does not always = better gas mileage an engine's efficiency is based on the ability of said engine to fill the cylinders with the given mixture expressed as a percentage of the cylinder's potential volume and how well it burns the total mixture. If the proportions are off (lean or rich) then it will not burn properly thus decreasing efficiency. I can give you the formula for it if you want...in fact here

VE = (HP x 5600) / (RPM x displacement)

I can keep going if you want to argue with me some more...

 

I think even you'd agree that less restriction = better gas milage. It's really a matter of how you drive it though. If you put the throttle at the same position you normally do, it's easier to suck in air, which means it will use more gas. If you use less throttle then it uses less gas. It's easier for the engine to pull air so there's less load on the engine. If you load the engine less, you use less gas. But at the same time, at full throttle there's much less restriction so you can pull in much more air which uses much more fuel.

 

Very true and good point, this is why I said it does not ALWAYS = better gas mileage. Under normal driving conditions and not under acceleration your engine will have less of a restriction and will show a very slight gain. That, still, is not enough to overcome the fact that while accelerating with less restriction more air is inherently pulled in thus using more fuel, and unless you never pull away from a red or try to get your car moving at all, it will affect your gas mileage negatively. Your noticeable gain would only be noticed at constant throttle, long distance, highway driving which as soon as you do anything else to your car will diminish. I am hoping that you guys are still open minded enough read what is written and not just accept and spout back the first thing someone read off an AEM box and typed on the internet. I have worked directly with Harley-Davidson and Screamin' Eagle and this kind of stuff is what I do. Also before anyone says "well that's a motorcycle", yes I know, but engine physics is still engine physics no matter if it's 2 cyl. or eight. I am always up for a healthy discussion so DTN, funkypc, please keep it up and maybe you can point out something else I didn't mention or think about...

 

is anyones goal with a CAI to improve gas mileage? no, its to add horsepower, which it does. I do think that if you drive it at the same or less throttle you could show a SLIGHT increase. Is it the 3-6mpg or whatever all the ebay places claim, definately not. and i know that even if i tried to drive my car easy and shift low, i would eventually get tired of it and get it up to the high rpms. goodbye gas mileage. sure the tib is decent on gas, but thats not why i have mine. its fun to drive, the reason i ditched the 1.6 nissan 200sx i had which got 35 mpg and picked up a rd1 for winter which gets like 25.

 

I am going to have to agree with Ham on this one, while the CAI makes your engine more efficient and allows you to pull in a larger intake charge, the ECU is going to have to add more fuel to the charge for proper detonation to take place. More Air does equal more horsepower, but it is also going to equal more fuel. Using fuel in larger amounts should cause your milage to decrease. That being said I don't think the decrease is going to be anything major.


Keep in mind that you are talking about power efficiency in this respect, not fuel efficiency, those are two totally different things. As a general rule, more power = less fuel economy. Thats why our little four bangers get better milage than most 6 and 8 cylinders, and why engines with forced induction typically get worse fuel economy than naturally aspirated versions (with varying degress depending on how hard the car is driven)

 

^^^I'm glad someone has mine and Ham's back on this...There are several different types of efficiency i.e. Volumetric Efficiency, Combustion Efficiency, Thermal Efficiency, Fuel Efficiency, etc. so you can't just say general efficiency because all of those mentioned are a factor. AEM's claim is based on a partial throttle cruise test, so yes there is a 1-2 MPG increase but unless you are only counting time in which you are already moving and you are only going 30 MPH then it will decrease slightly. All the stuff spouted on the boards about it since AEM came out with a CAI for the Tib came from uninformed individuals and is based on AEM's claims.