I went with the Injen intake. K&N has apparently had one in development for the Altima for several months now but, no dice yet. Injen's marketing suggests that their intake is "tuned" to mitigate any ECU problems. What that means and how "true" it is I really couldn't say.

I think that victore1123's point is well taken, judicious use of the gas pedal will likely do more for FE than any aftermarket modification. Still, I'm going to try it. I just hope to resist the urge to hear that little 4-banger growl

 

Can't argue with that, the growl and peppier engine responses are tempting...

 

Ok, here is the data i acquired with today's test. Highway MPG increased significantly for the 65 mile commute at 60mph. Acceleration deteriorated to abysmal level, more like that of a "really slow hybrid"!!! DTE also increased based on mpg display. I could not find any reference to causing engine damage (melting the pistons) because of obstructed air intake, but I am concerned and almost nixed the test after 30 miles. No other anomalies were detected except for the reduced acceleration "so far".

 

I'm sorry Victor, but really no surprises here. What you've done is akin to placing a brick under your gas pedal. You're starving the engine of air, it refuses to lean out the mixture, it cuts back on the fuel to maintain the correct mixture. But I would be concerned at what else the engine may be doing to compensate. Not something I would do with my $28K vehicle. At some point you need enough airflow to atomize the fuel correctly. I imagine you are putting your engine management system through hell right now.

 

^I'm wondering if the same comments could be made about feeding "too much air" to the engine, that is, damage could be done?

Would anyone advise against using an aftermarket intake?

 

I'm not sure if too much air is a bad thing. But on that note. When I used to dabble in Mustangs (at least the newer ones), you had to replace the MAF sensor if you went to a bigger intake. Did your new plenum come with sensors?

This past weekend I bought my 16 yr old daughter her first car, a 98 Escort. So naturally I went over the thing from head to toe. One thing Ford's are notorious for is dirty throttle bodies, and you get a huge benefit when you clean them. I noticed on the instructions for this particular TB cleaner, they instruct you to disconnect the battery after your cleaning. The difference in air flow can be so dramatic after a good cleaning that the cpu actually should be reset to learn how to manage the flow again.

 

I dabbled a little also, when I was younger. Increasing airflow was little benefit to performance (acceleration) only because the capacity of the system to provide the additional fuel was limited. Same as the old, ram air systems, you would have to be traveling at 165 miles per hour to create enough pressure in the system to be of any benefit. Again I'm sticking to the old adage that reducing the performance will increase FE.
I don't recommend anyone try what I am doing, lest they mess up the car and blame me, but my DTE is giving me over 900 miles for the remainder of this tank (it was not a full tank when I started the test) Another drawback is that I will have to clean out my mod every 3 days or so.

 

ok...

i don't think that decreasing the air will do any damage to your car, your ecu will just compensate with restricting the fuel. like someone else said, it's the equivalent of sticking a brick under your pedal. i do think it might have a negative impact of fuel efficiency while going at higher speeds since it will have to work harder to get enough air into the valves.

 

How is it working harder? If it takes 15HP (let's say) to go 65MPH, it takes the same energy whether or not the intake is restircted. Unless the mixture is messed up, that energy will come from the same amount of fuel.

I do agree there is no harm to the engine driving with the restriction in place. The risk I see is not being able to drive on the road without being a hazard to other drivers because you are going slower than they expect (like merging onto a highway).

-dan

 

I think you have to think about the intake stroke. As the piston is on the down stroke and the intake valve is open, it draws air/fuel. If you plug up the air intake, that downstroke will have more force against it, i.e., it has to work harder to draw in the mixture (vacuum). That will take more power. That power is provided by another cylinder's power stroke. The entire engine is working harder because it is more difficult to draw in air.

You need some resistance, I think it's called the venturi effect, but I would think too much is a bad thing.