well, can it?

im thinking, air duct, pop-charger, and any other mods made for better air-flow.

thank you.

 

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Generally, MPG is not a priority with bolt-on mods such as those that you named. The priority is peak hp and torque. Consensus is that the MAF senses more air, adds more fuel increasing hp. If weight is held constant, then a vehicle with 300 hp will get less MPG then the same vehicle with 275 hp. So the answer to your question is no.

 

Here's a different way of looking at it....

To drive down the highway at 50 mph in 6th gear, let say the throttle is opened 45%. You make some mods that allow the engine to breathe better - plenum spacer, pop charger, etc. So now when the throttle is opened 45%, more air is actually able to flow into the engine.

As davidv assumed, the ECU recognizes the increased air flow and increases the fuel flow to match. But since you have more air and fuel you're getting more power so you can actually back off on the throttle to travel the same 50 mph speed. Less throttle means less fuel again, less fuel per mile means increased MPG.

Doesn't every car manufacturer and air-filter manufacturer stress the importance of maintenance, especially a clear air filter, on your gas mileage? That's a simple example of more air flow resulting in higher MPG.

 

backing off the throttle wont get you from 45 to 50mph.

you car will go the same speed in the same gear no matter how much hp you have. (thats in theory, gotta have hp to over come air resitance/drivetrain weight) if your engine is turning at 3000 rpm in 6th with 300hp youll be doing ~80mph. strap on tt and a built engine and youll still be doing ~80mph. if you dont modify the transmission/fd or tire size then youll still go the same speed. engine rpm is directly realted to tire speed for each gear. where it matters is when you want to stomp the gas....youll accelerate faster.

 

I always thought that more airflow = more fuel = less MPG.

 

Whoa, go back and reread carefully. I never said anything about 45mph. I just used 45% opening of the throttle as a relative starting point.

True, the car travels the same speed for the same rpm, but if it takes more throttle to get that same rpm, then you're burning more gas. All I'm saying is that if the air flows into the engine more efficiently, then you would get more power. To keep the same speed, you need the same power for any throttle postion. If the increased air flow would give you more power, that would make you go faster. So you back off on the throttle a little to keep the same speed.

 

so are you guys saying that something like intake can actually hurt the gas mileage?

 

That's the debate. While more air = more gas = less MPG (IMHO), the improved airflow can actually make the engine more efficient. So I dunno if an intake and/or exhaust helps or hurts MPG. It's probably both.

 

don't most of the companies claim that their intake result in better gas mileage tho? but then, thinking about the air/fuel mixture, im starting to wonder how more air flow will result in better gas mileage. hmm....

 

But the increased air flow most likely caused the ecu to compensate by increasing fuel flow at any given throttle position as well. You might be able to open the throttle less, but have more air and fuel flowing through. In the end the same amount of fuel is used. It's a wash at best I'd guess.

 

Actually, the reality of the fact is that any performance modification decreases gas mileage.

Here's why - when you put on an exhaust, pop-charger, lightweight pulleys, etc., you just can't resist the urge to punch it! Admit it, what's the first thing you do, you take it out for a "performance" test drive.

 

Yes... Plain and simple, gave me about and extra 2 miles per gallon... I am at 24 city mpg.

 

If you do not change the weight of the car or the gearing, then it is all about A/F ratio and overall driving habits. Some air flow mods can lean out the A/F ratio and others might cause the ECU to respond and go a little rich. The second post shows you where you want the A/Fto be for maximum MPG. The 6MT guys could install 5AT rear ends as well to get better MPG.

 

Usually breathing mods will lean out your a/f mixture a bit which will cause you to get better mpg. The ECU can (and often does) correct for changes in air flow, so your a/f may stay similar. But overall, if anything, you will see an increase in MPG. (If you don't floor it all the time now that youve got your new mods!)

 

Extra Air Flow vs. Removing a restriction. The engine is pulling in as much air as it needs. If you are driving at a constant throttle you should be pulling in roughly the same amt. of air regardless of whether you have an open intake or a filter on it. What it boils down to is how hard the engine has to work to pull in the air. By this logic going with a less restrictive air filter would increase mpg because the engine doesn’t have to work as hard which means it doesn’t need as much gas. On the other side of the spectrum, if you are forcing air into engine (ie. turbo or super) it needs more fuel to prevent a lean condition causing worse MPG. Thats my take on it.

 

wow. very interesting. thank you guys. imma study a little more on this.

 

HOw much wood, would a woodchuck chuck, if a woodchuck could chuck wood?

 

eh you're gonna pay out the nose with gas on this car regardless...

 

No kidding! Look at your mods!!
My Z is almost stock, and I got 21mpg with 20%hw/80%city daily drive.
What is wrong with my Z?