Does having a Cold Air Intake upgrade (Injen, Nismo) have an effect on the gas efficiency? Rationally speaking, I would think it would decrease gas efficiency b/c it adds more horsepower. Any yall know the answer? Thanks.

 

I doubt it's going to make much difference one way or another, but I'm gonna guess and say you'll take a slight hit on mileage with the mod.
Of course the temptation to make the intake and exhaust 'sing' a lot will cost more........[img]/w3timages/icons/tongue.gif[/img]
GSM

<font color=red>GSM</font color=red> <font color=black>Silverstone Coupe</font color=black>

 

Heck no! My car is running more effeciently due to better air flow. My MPG jumped 3 MPG after installing my Z-Pipe / Stillen Intake. The part that ruins your gas mileage is reving the motor too often to hear that sweet sound. [img]/w3timages/icons/cool.gif[/img]

 

I would think that your MPG’s would improve with a CAI since it allows a little more air to flow.

It’s like if you have a dirty air filter, the car will lose some MPG’s cause the airflow is restricted by the dirt, but with a new clean air filter your MPG’s improves cause it allows more air to flow in, make sense.

 

It depends on how you drive. If your light on the gas you'll see an increase in millage. The faster you go the less millage you'll get. Even less then with your stock intake. Maybe because the ecu is dumping in more gas to match the increased amount of air? Just telling it how I experience it, I don't know the mechanical stuff involved.

BS G35C 6spd navi/aero/prem

 

What about an Exhaust's effect on gas efficiency? For example in the case of an Injen intake and Injen exhaust.

 

You get worse or same milage until the ECU reverts to the baseline where air is increasing so fuel is decreased to provide the same power as before the mod. This is when you reset.

 

Good question, this is a commonly misunderstood principle:

The ECU, MAF, and other electronics are constantly doing their best to keep the air:fuel ratio at 14.7:1. Even with better flow, you still need the same amount of fuel to produce the same amount of power. Extra power does not come from extra air, it comes from burning the extra fuel allowed from the better airflow. If you don't increase fuel with increased airflow, the excessively lean mixture will burn valves, rings, and lots of other goodies from the insane temperatures generated under those conditions.

All this means changing the air intake will cause the car to behave normally until you push it passed it's previous airflow limit. Once it goes beyond that, it uses more fuel and produces more power. Since no device (especially a car) is 100% fuel efficient, this means some of that extra power get's lost by the time it hits the road, resulting in an overall decreased fuel economy.

The only case in which better airflow can increase fuel economy is where the engine has significant design flaws resulting in a nonoptimal fuel-air mixture that is subsequently corrected by the increased flow. Since the G has a computer-controlled mixture control system, this is not the case.

If you change your intake and drive conservatively, you shouldn't notice any significant fuel economy change as a result. However, once you push your car beyond it's previous power limit, you will use more fuel to do so and decrease your fuel economy in trade.

That said, my first tank of fuel with the Nismo intake is about 1.8mpg lower than it was stock, but I'm driving it harder than I was previously. I suspect if I drove normally it would be about the same.


03.5 Coupe - Black/Willow, 6MT, Premium, Navi, Aero, Sat

 

Thanks for your input everyone.

 

lol ya what shader said. Thanks for going more indepth Shader, I couldn't think of any better way to explain it.

My first tank with the CAI I actually got 22mpg vs. my 19.3 because I went easy on the car. Then it dropped to 17 or 18 when I started driving more comfortably.

BS G35C 6spd navi/aero/prem