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Discussion Starter #1
I've heard from "people" that if you add an intake you get better gas mileage. Obviously I don't know if its true or not, so i'm asking whoever that has an intake does it give you better or worse mileage? In my opinion i'm assuming less mileage because supposlby adding intake gives you an extra 2hp+, and more hp burning more gas? Well correct me if i'm wrong, I would just like to know if I should invest in one or not.
 

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As long as you drive the vehicle the same after you install the intake it will increase your mpg. People run into problems though b/c the tend to drive a little sportier after they install an intake because of the added sound and performance. As long as you can keep your driving habits the same you will gain some fuel economy but don't expect miracles.
 

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I have wondered about the same question with other performance mods, if you add hp then does it increase the efficiency?
In my mind is seems that if the engine is more powerful then i wouldn't need to rev it as high to get the same result as before the mod and therefore would save gas; but that isn't necessarily how it works in the real world. i know there would be many factors at play here including how the engine manages the air-fuel ratio, the temp of the air going into the engine and the engine's timing among others.
Has anyone here been able to increase fuel economy by modding? ie intake, exhaust, turbo etc
i have been considering adding k&n filters to help economy but keep wavering as to weather i should just replace the stock filter and reuse the stock air box or get the typhoon intake on both of our vehicles (09 cube base and an 08 Sebring vert) My cube is averaging 30mpg which is a HUGE improvement from the 14mpg the ram i traded in got.
there are other mods i've seen online (like the halo spark plugs) that claim to boost efficiency, but i'm not quite brave enough to try just yet.
 

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Discussion Starter #4
twistedframe said:
As long as you drive the vehicle the same after you install the intake it will increase your mpg. People run into problems though b/c the tend to drive a little sportier after they install an intake because of the added sound and performance. As long as you can keep your driving habits the same you will gain some fuel economy but don't expect miracles.
hmm thanks, i guess i'll have to try it and if the mpg slumps i will probably take it out and resale it
 

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i think you gain a bit more then 2hp....i have a fujita phototype right now i can say i get about the same gas miles. but you gain power by more air so it does not waste more gas in any way
 

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Your fuel injected car adjusts the amount of fuel used to compensate for the additional air being put in the combustion chamber.

You won't add mpgs by adding and intake. Period. Some people might claim it due to being light on the pedal but the math of it is simple. A car runs from the factory set at a specific tolerance of fuel and air mixture, adding the intake drastically increases the air in the situation and therefore the computer adds fuel to keep the same tolerance of fuel to air mixture.

I personally had an intake on my last car, 05 pt cruiser turbo. It got 19 mpg in the city with the intake on it. After I decided to sell it, I put the stock box back on (with k&n drop in) and jumped to 22 mpgs.


I do believe a drop in filter that allows the air to flow better but doesn't drastically increase the air volume has potential to give additional mpgs, at least on some applications.
 

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actually there are 2 sides to this. I don't know if the 1.8 is DI or not but I'm guessing no coz that's an expensive tech and this is a cheap car.

So for a non DI vehicle there are 2 possible outcomes if you modify your intake system.

1. The fuel economy has improved: This is due to an easier breathing intake causing a better atomization of gas, as well as more efficient filling of the combustion chamber. In many cases when you drive the vehicle with the normal intake (if you had a vacuum gauge) you will see a surge in vac and there is a certain amount of drag caused by a restrictive intake system. However this being a 2009/2010 car I would imagine Nissan has done everything in its power to maximize the factory intake efficiency for max mpg. Also a less restrictive intake causes the driver to feel that the car has more power and psychologically he MAY tend to put less throttle input just because of that, causing the ECU to use the fuel map mapped towards a lesser throttle opening, thus reducing the fuel consumption. Logically the only bad thing Nissan COULD have done is to install paper filter to reduce cost, I would be very wary about altering the intake tract or other portions of the intake system prior to the throttle body.

2. The fuel economy has deteriorated: The driver might drive more aggressively because of the added sportiness or sound from the brand new intake. This would be the biggest factor in a sloppier MPG after install. The other possibility is the lack of ram speed due to the freed up intake system, causing fuel to atomize less optimally (again, I'm assuming we have a port injection engine) at the intake valves. This is not the result of a poorly made intake, but rather, an intake designed for a different goal - the ram speed is probably more optimal at higher RPM for its claimed "HP increase" by shifting the ram speed to become more optimal at high volume operations. However, poor atomization of the fuel at lower RPM gives this sense of "losing torque" at lower RPM, causing the driver to press the go pedal deeper in hopes to regain the loss, this would significantly increase fuel consumption as that is going to scale the engine management's fuel map to a higher load/higher performance section.

So it really depends on how the intake system is designed to do. What will be a telltale sign of a good intake system is that you find yourself driving at the same speed with lighter throttle, causing the engine management system to choose a lighter load operation mode.

To be safe it's probably best to just replace the paper filter with a high-flow drop-in unit from an aftermarket manufacturer. That way, you are ensured most optimum Nissan engineering without the cost cutting. Anything more "modified" may or may not help the cause.

What about engines with direct injection? Well the air is always mixed with the fuel before it's released into the combustion chamber as a "packet" of combustible so there will really be no significant difference unless the car is having a hard time breathing through its intake system...
 

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As someone who has modded motorcycles, here is what I found:

Installing a K&N (or making the intake more effecient) allows more air to flow or flow easier. Since the cube is computer controlled, it will increase the amount of fuel taken in in order to keep the mixture the same, so, no net change in normal driving, BUT if you were to romp on it, you would be able to get more air easier and thus more fuel, so drop in MPG.

The only really good ways to get better MPG is:

Drive consertatively. In my Hyundia I found that if I drove at 65 mph on the freeway, my milage was a lot better than if I drove at 70 mph. At 75 mph my milage really dropped.

Reduce weight. Get rid of anything you don't need. If you are confident enough, lose the spare! I carry a plug kit and a tire inflater which together weight much less than the spare.

Overinflate your tires SLIGHTLY. Running the tires a pound or 2 above the door sticker can help. More than that will wear the centers prematurely, make the ride rough and increase chance of a blowout.
 

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its all good info but if you dont look at the whole picture then your not getting the best idea of whats going on.

keep in mind everything youve just read above and think about this.
at part throttle ( where most people drive ) you will have less restriction on the air coming into the engine, so your engine will work less to get the same result. the new filter will flow more freely, so your engine will work less to get more.
now in past cars ive owned, some of the intakes have been too small for the car i.e. 95 trans am. the stock intake was a bottleneck for a 5.0l engine at 3k rpms, it was on a 5.7l motor that spun to 5700. i saw massive gains throughout the rpm band just by swapping to a larger intake.
most new cars are not like this.
on my cobalt, i swapped out to a 3in intake. the check engine light came on and my gas milage went down. the maf started to read way more volume and couldnt compensate for it. we scaled the maf frequency and the gas milage went way up. didnt see much in hp but the engine loved the change.
now on top of air flowing more freely into the engine, you can gain hp and milage by the engine not compensating for the air coming in and leaning out the mixture, not highly likely but could happen. i say all this because every car is different, every manufacturer is different, the aftermarket will make some things that work and some that dont. hopefully some pioneers on here will figure it all out.

o ya just for thought, my cobalt gets a hair over 44mpg on the highway and makes just under 360whp. kind of a fun mix, but doesnt do this at the same time. hoping to run low 12's this season with it
 

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Like someone else said already, it will depend on your driving habits before and after. I myself have never been one to "Take it easy" on the throttle.

On mine with a 6 speed and the stock intake system I got between 29.6 and 30.8 MPG pretty consistant. Several months ago I installed an Injen intake and I'm currently getting between 30 and 32 MPG and my driving habits haven't changed. But I do get better acceleration, crisper throttle response, and it sounds GREAT. Although I did actually get a slight increase in mileage (based on what the computer tells me) it isn't a great amount. But for sure it hasn't decreased. The reason for the fairly wide spread in average MPG is because I live in a mountainous area and drive my car for business. Sometimes I drive in fairly flat areas, and other times I drive the mountains, and it varies. All in all my intake has worked out for me, and it is an improvement all around over the stock intake. - Dano
 

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The way an intake will increase your mpg is that the hotter the air in your motor the leaner the motor gets the more timing is pulled blah blah blah it works if done right... the problem is most people after a intake just floor it all the time :no:
 

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I know it's an old thread, but if I might add some personal experience.

I bought my 2005 Silverado new and stock it got around 17MPG on average and 20MPG on the highway. When I added a ram-air intake, cat-back exhaust and switched to full synthetic motor oil I gained 2MPG average and I've seen as good as 24MPG on the highway at 65MPH.

I'm not saying the same thing would make such a drastic change to the cube, but I plan on doing the same mods to my cube after a few thousand stock miles.
 

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Part of the advantage of a cai is the simple physics of the air itself. The colder the air the more dense it is. The more dense the air is, the more oxygen molecules are present. The more oxygen present in the combustion chamber, the better the burn will be.

Class dismissed. ;)
 

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One thing that could play against good or bad mpg is the A/F ratio. For personnal experience, I had a Sentra SeR SpecV before the cube, and on some board, members who added intake, header, catback and a Apex'I SAFC2 device to adjust A/F ratio did saw a better mpg and getting more ponies out of the b15.

But it must be said that 2002-03 B15 SeR SpecV were know to be running too lean at low rpm and too rich at high rpm. So by correcting the A/F ratio with the SAFC2 to a 13.5 iirc, the car was running smoother. It was a waste of money on 2004-06 on the other hand since the problem was corrected and these one nearly had perfect A/F ratio on all the powerband.

To know how the A/F ratio is on the z12, just plug an o2 wideband on it to check it out and see if anything have to be corrected.
 

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one thing to keep in mind... you can't change the basic laws of thermodynamics, no matter what you really want to believe. To get more power, you have to throw more fuel on the fire. More power and better mpg do not go hand in hand. You can't have both.
 

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lonlawrence said:
one thing to keep in mind... you can't change the basic laws of thermodynamics, no matter what you really want to believe. To get more power, you have to throw more fuel on the fire. More power and better mpg do not go hand in hand. You can't have both.
You can make the engine breathe easier with an intake and exhaust and if you drive efficiently you can take advantage of that gain in efficiency.

A Corvette is rated for 26MPG highway with a 6.2L engine. Drivers that drive efficiently routinely see 30MPG on the highway despite the displacement. Reason? Efficiency.
 

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AndrewGS, I see you replying (arguing with) all my statements. You're all wet. While a particular engine may be designed to run at a given mpg, increasing the airflow will increase the fuel flow. You know nothing about thermodynamics or the computers used in our modern autos. I repeat, TO GET MORE POWER, YOU HAVE TO THROW MORE FUEL ON THE FIRE. MPG AND POWER DO NOT GO HAND-IN-HAND. IF YOU GET MORE POWER OUT OF A GIVEN ENGINE, YOU HAVE TO BURN MORE FUEL "IN THAT ENGINE." CHANGING THE ORIGINAL CONFIGURATION OF THE ENGINE WILL AFFECT YOUR FUEL MILEAGE. I HAVE 45 YEARS EXPERIENCE AS AN ASE MECHANIC AND I HAVE BUILT MORE HOT-RODS THAN YOU HAVE EVER SEEN SEEN. GET REAL!
 

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Actually, the more efficiently the vehicles stock engine can move the car at normal driving conditions, the better MPG you can get. Adding more power may burn more fuel, but it allows to car to move more efficiently. You can get better MPG with more power as long as you are not heavy footed.
 
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